COURSE INTRODUCTION: The study of the human body becomes relevant only if the subject matter is correlated well with the clinical problem . It becomes more relevant if it can be clearly demonstrated that what the medical students are learning now will be important in their subsequent studies and throughout their practice in the art of healing. It is said that ANATOMY is the foundation of all branches in medicine. Unfortunately, the time allotted to this subject in the average medical course is not sufficient. The BACK, as a region of the human body, is one of the most frequent sites of complaint in clinical practice. As such, it is of human interest that it should be a focus of learning. The anatomic basis of these, however, is the student’s interest. For this reason, it is more appropriate to call this learning process on human anatomy as CLINICAL ANATOMY.

There are 4 main objectives that we aimed to achieve at the end of this module. First, is to know the importance of the back. Normally, it is one region of the body that is hardly seen, not unless one has to see it intentionally. It is anatomically outside the peripheral vision. One becomes aware of the back when it becomes the primary site of pain and discomfort for whatever reasons. Second, the BACK is not an insignificant region. Clinically, medical conditions arising from this part of the body are, at times, very difficult in terms of diagnosis and treatment. It contains one of the vital structures of the body- the spinal cord. The third objective is to correlate the anatomic form with the functions of the different structures of the region. Take the vertebral column, for example, why is the vertebral body of the lumbar vertebral region bigger in size compared to the vertebral body in the thoracic or in the cervical vertebral regions? The 4th objective to correlate clinically the anatomy of the back region to the conditions that bring the patient to the doctor.

Due to the close association with the trunk, the back of the neck and the posterior and deep cervical muscles and vertebrae are included in the discussion of this anatomic region. The BACK consist of the following: 1. the skin, 2. subcutaneous tissue ( a layer of loose irregular connective tissue containing cutaneous nerves and vessels, 3. deep fascia, 4. muscles, 5. ligaments, 6. vertebral column, 7. ribs (in the thoracic region), 8. spinal cord and meninges, and 9.various segmental nerves and vessels.

Basing on the strict definition of the back region, there are only 4 regions of the back. But then the attachment of the posterior aspect of the neck and the lower extremities, the posterior cervical region proximally and the sacral regions distally are included.

The diagram above is a transverse section of the upper abdomen and it shows the vital structures of the abdomen at this region. Take note that at the anterior portion of the abdomen has a thin-walled abdominal wall which is composed of few layers of soft tissues. In terms of defense against an injuring force, this type of wall predisposed the abdominal contents to injury. However, this weakness is compensated by the presence of vision directed anteriorly and laterally. On the other hand, the posterior abdominal wall is composed of massive layers of osseo-muscular structures that can withstand an injuring force of great magnitude. The posterior abdominal wall, however, is not in line with vision.

The above illustration shows the massive musculo-osseous wall that protects the vital structures inside the thoracic cavity

The back acts as a solid musculo-osseous shield that protects the SPINAL CORD- A structure that gives life to the limbs. While the back doesn’t give an absolute protection to the spinal cord at all times against a severe injuring force, it does give protection most of the time. Injury to the spinal cord results in paresis (weakness or incomplete paralysis) or, in severe cases, complete paralysis. There’s an adage that goes “life is motion, motion is life”.

The spinal cord also contains the nerve fibers that make up the AUTONOMIC NERVOUS SYTEM which regulates practically all the physiological functions of the body.

The back is also one of the most frequent site of affliction that brings patient to the clinic. Back pain is a universal problem.

The muscles of the back are classified into EXTRINSIC and INTRINSIC muscles. Extrinsic muscles are so called because they function mainly to support the stability and motion of the upper extremities. They do not primarily support the spine, or vertebral column. On the other hand, the intrinsic muscles of the back function mainly to support and stabilize the vertebral column The extrinsic muscles are characterized as flat and broad muscles while the intrinsic muscles are cordlike that span the vertebral column.

The EXTRINSIC MUSCLES occupy the superficial layers of muscles at the back and are arranged in layers. The most superficial muscles are flat and large muscles like the TRAPEZIUS and the LATISSIMUS DORSI. The second and third layer of extrinsic muscles are small but still are flat. The first and second layer of extrinsic muscles support the functions of the upper extremities while the third layer support the function of respiration. The 2nd layer of extrinsic back muscles are found posterior to the first layer. These consist of the levator scapulae, rhomboid major and rhomboid minor. The 3rd layer consists of the serratus posterior superior and the serratus posterior inferior.

The extrinsic muscles differ from the intrinsic muscles in innervation. The extrinsic muscles are innervated by nerve fibers from the anterior( ventral rami) of the cervical nerves. The intrinsic muscles, on the other hand, are innervated by fibers coming from the posterior (or dorsal) rami of the cervical and thoracic.

The SUPERFICIAL EXTRINSIC BACK MUSCLES are composed of the following: the TRAPEZIUS muscles, the LATISSIMUS DORSI, the RHOMBOIDS (major and minor) and the LEVATOR SCAPULAE. The cephalad half of the back is dominated by the TRAPEZIUS while the caudad half by the LATISSIMUS DORSI. Underneath the TRAPEZIUS and at the level between the medial aspect of the scapula and the vertebral column, the RHOMBOIDS (major and minor) are located. Just above the RHOMBOIDS is the LEVATOR SCAPULAE. These extrinsic superficial back muscles are associated with the function of the upper extremities and not with the motion and direct support of the vertebral column.

The TRAPEZIUS MUSCLE(from the Greek word, trapezion- which means irregular 4-sided figure). When taken as a one-sided muscular structure, it is a triangular-shaped muscle that covers the back of the neck and upper half of the thoracic region. It attaches the pectoral girdle to the skull and to vertebral column. It also assists in suspending the pectoral girdle. ORIGIN of the TRAPEZIUS: 1. UPPER PART: from the EXTERNAL OCCIPITAL PROTUBERANCE and the INNER THIRD OF THE SUPERIOR CURVED LINE OF THE OCCIPITAL BONE; 2. the MIDDLE PART: arises by a broad triangular aponeurosis, which reaches from the 6th cervical vertebra to the 3rd thoracic vertebra. The LOWER PART arises by short tendinous fibers from the spinous processes of the last 9 thoracic vertebrae with the corresponding supraspinous ligaments. INSERTION: the superior fibers proceed downward and outward, the middle fibers horizontally, the inferior ones upward and outward. These are inserted to: the superior ones into the outer third of the posterior border of the CLAVICLE; the middle fibers into the inner margin of the ACROMION PROCESS, and into the superior lip of the posterior border or crest of the SPINE of the SCAPULA. The inferior fibers converge near the scapula, and terminate in a triangular aponeurosis, which glides over a smooth surface at the inner extremity of the scapular spine, to be inserted into a tubercle at the outer part of this smooth surface. If the trapezius is dissected at both sides, the two muscles resemble a trapezius or diamond-shaped quandrangle; two angles corresponding to the shoulders; a third to the occipital protuberance; and the fourth to the spinous process of the last dorsal vertebra. The anterior margin of its cervical portion forms the posterior boundary of the POSTERIOR TRIANGLE of the NECK, the other boundaries being the STERNOCLEIDOMASTOID in front and the CLAVICLE below. INNERVATION : CRANIAL NERVE XI (Spinal Accessory); branches from the anterior divisions of the 3rd and 4th cervical nerves. ACTIONS: Acting in association with the other muscles inserted into the scapula, the TRAPEZIUS steadies the scapula and controls its position and movements during active use of the upper limb. In this way it is responsible for maintaining the level and poise of the shoulder. Acting with the LEVATOR SCAPULAE, its upper fibers elevate the scapula and with it the point of the shoulder; acting with the SERRATUS ANTERIOR, it rotates the scapula in a forward direction so that the arm can be raised above the head; acting with the RHOMBOIDS, it retracts the scapula and so braces back the shoulder. When the shoulder is fixed, the TRAPEZIUS draws the head backwards and laterally.

The LATISSIMUS DORSI is a broad, flat muscle which spans the lumbar and the lower half of the thoracic regions, and as it ascends to its insertion in the humerus, it is condensed into a narrow fasciculus. ORIGIN: It originates by tendinous fibers from the spinous processes of the 6 inferior thoracic vertebrae and from the posterior layer of the lumbar fascia, by which it is attached to the spines of the lumbar and sacral vertebrae and to the supraspinous ligament. It also arises from the external lip of the crest of the ilium, behind the origin of the external oblique muscle, and by fleshy digitations from the 3 or 4 lower ribs, which are interposed between similar processes of the external oblique muscle. INSERTION: From the extensive origin the fibers pass in different directions- the upper ones horizontally, the middle obliquely upwards, and the lower vertically upward, so as to converge and form a thick fasciculus, which crosses the inferior angle of the scapula. It then curves around the lower border of the TERES MAJOR, and is twisted upon itself, so that the superior fibers become at first posterior and then inferior, and the vertical fibers at first anterior and then superior. It then terminates in a short quadrilateral tendon, about 3inches in length, which, passing in front of the tendon of the TERES MAJOR, is inserted into the bottom of the bicipital groove of the humerus, its insertion extending higher on the humerus than that of the tendon of the PECTORALIS MAJOR. At the region just above the Iliac crest, the outer margin of the latissimus dorsi is separated below from the EXTERNAL OBLIQUE muscle by a small triangular interval, the TRIANGLE OF PETIT. Another triangular interval exists between its upper border and lateral margin of the TRAPEZIUS, in which the RHOMBOIDEUS MAJOR muscle is exposed. This is clinically known as the triangle of auscultation. INNERVATION: by the MIDDLE and LONG SUBSCAPULAR NERVE ACTIONS: 1. Plays an active part in the movements of adduction, extension and medial rotation of the humerus. Further, it acts with the sternocostal part of the Pectoralis major and with the Teres major to depress the raised arm against resistance. When the arms are raised above the head and fixed, e.g., by gripping a horizontal bar, the same muscles act to pull the trunk upwards and forwards, a movement in which their origins are approximated to their insertion. In addition, the Latissimus dorsi takes part in all violent expiratory movements, such as coughing and sneezing, and when the fibers of the muscle are put in the stretch as in the elevation of the arm, their tonus enables them to exert sufficient pressure on the inferior angle of the scapula to keep it in close contact with the chest wall. A triangular space located behind the scapula, known as TRIANGLE OF AUSCULTATION, is bounded above by the TRAPEZIUS, below by the LATISSIMUS DORSI, and laterally, by the medial border of the scapula; the floor is partly formed by the RHOMBOIDEUS major. If the scapula be drawn forwards by folding the arms across the chest, and the trunk bent forwards, parts of the 6th and the 7th ribs and the interspace between them become subcutaneous in this situation.

The lower part of the lateral margin of the Latissimus dorsi is commonly separated from the posterior free border of the External oblique muscle by a small triangular interval, the Lumbar Triangle of Petit, the base of which is formed by the iliac crest, and the floor by the Internal oblique muscle.

In the above illustration, at the cephalad I/2 of the back, the rhomboids and the levator scapulae are dissected out to show the Serratus Posterior Superior muscle. At the distal one half of the back, the Latissimus dorsi muscle is dissected out to show the Serratus Posterior Inferior muscle. Both serrati posterior muscles are considered as the intermediate layer of extrinsic muscles.

The second layer of superficial extrinsic muscle of the back are those immediately behind the TRAPEZIUS muscle. These muscles are the LEVATOR SCAPULAE, the RHOMBOIDEUS MAJOR and the RHOMBOIDEUS MINOR. All these muscles are inserted into the scapula. LEVATOR SCAPULA : This muscle is situated at the back part and side of the neck. It arises by tendinous slips from the transverse process of the ATLAS, and from the tuberles of the transverse processes of the 2nd, 3rd, and 4th cervical vertebrae. These muscles, becoming fleshy, are united so as to form flat muscle, which, passing downward and backward, is inserted into the posterior border of the scapula, between the superior angle and the triangular smooth surface at the root of the scapula. RHOMBOIDEUS MINOR: Arises from the LIGAMENTUM NUCHAE and spinous processes of the 7th cervical and the 1st thoracic vertebrae. Passing downward and outward, it is inserted into the margin of the triangular smooth surface at the root of the spine of the scapula. This muscle is separated from the RHOMBOIDEUS MAJOR by a slight interval. RHOMBOIDEUS MAJOR: This muscle is situated immediately below the RHOMBOIDEUS MINOR, the adjacent margins of the two are being occasionally united. It arises by tendinous fibers from the spinous processes of the 4 or 5 upper thoracic vertebrae and the supraspinous ligament, and is inserted into a narrow tendinous arch attached above the lower part of the triangular surface at the root of the spine; below, to the inferior angle, the arch being connected to the lower border of the scapula by a thin membrane. INNERVATION: The Levator scapulae is supplied directly by the 3rd and 4th cervical nerves, and from the 5th cervical nerve through the DORSAL SCAPULAR nerve. The RHOMBOIDS are supplied by DORSAL SCAPULAR nerve (C4, C5) ACTIONS: In association with other muscles that insert into the scapula, the RHOMBOIDS AND LEVATOR SCAPULAE help to steady the bone and to control its position and movements during active use of the upper limb. In this way, they help to maintain the level and poise of the shoulder. Acting with the TRAPEZIUS, the RHOMBOIDS retract the scapula and brace back the shoulder; acting with the LEVATOR SCAPULAE and PECTORALIS MINOR, they rotate the scapula so as to depress the point of the shoulder. When the cervical part of the vertebral column is fixed, the Levator scapulae may act with the Trapezius to elevate the scapula, or to sustain a weight carried on the shoulder. If the shoulder is fixed, the muscle inclines the neck to the same side.

DISSECTION: To bring into view the third layer of muscles, remove the whole of the second layer together with the Latissimus dorsi, by cutting through the Levator scapulae and Rhomboids near their origin, and reflecting them downward, and by dividing the Latissimus dorsi in the middle by a vertical incision carried from it upper to its lower part, and reflecting the two halves of the muscle. The SERRATUS POSTERIOR SUPERIOR: A thin, flat, quadrilateral muscle situated at the upper and back part of the thorax. It arises by a thin and broad aponeurosis from the ligamentum nuchae, and from the spinous processes of the last cervical and two or three upper thoracic vertebrae and from the supraspinous ligament. Inclining downward and outward, it becomes muscular, and is inserted, by 4 fleshy digitations into the upper borders of the 2nd, 3rd, 4th, and 5th ribs, a little beyond their angles. SERRATUS POSTERIOR INFERIOR: Situated at the junction of the thoracic and lumbar regions; it is of an irregularly quadrilateral form, broader than the preceding, and separated from it by a considerable interval. It arises by a thin aponeurosis from the spinous processes of the last thoracic vertebrae and two or three upper lumbar vertebrae, and from the supraspinous ligaments. Passing obliquely upward and outward, it becomes fleshy, and divides into four flat digitations, which are inserted into the lower borders of the four lower ribs, a little beyond their angles. The thin aponeurosis of origin is intimately blended with the lumbar fascia.

The INTRINSIC BACK MUSCLES ( also known as MUSCLES OF BACK PROPER; DEEP BACK MUSCLES; TRUE BACK MUSCLES) are innervated by the posterior branches of the spinal nerves and act to maintain the stability of the vertebral column in posture and during vertebral column movements-FLEXION, EXTENSION, LATERAL BENDING, CIRCUMDUCTION. These muscles, extending from the pelvis to the cranium, are enclosed by the deep fascia that attaches medially to the NUCHAL LIGAMENT, the TIPS OF THE SPINOUS PROCESSES OF THE VERTEBRAE, the SUPRASPINOUS LIGAMENT, and the MEDIAN CREST OF THE SACRUM. The fascia attaches laterally to the CERVICAL AND LUMBAR TRANSVERSE PROCESSES and to the ANGLES OF THE RIBS. The thoracic and lumbar parts of the deep fascia constitute the THORACOLUMBAR FASCIA. The deep back muscles are grouped according to SUPERFICIAL, INTERMEDIATE, and DEEP layers according to their relationship to the surface.

The most superficial intrinsic muscles of the back are found at the neck region- the SPLENIUS MUSCLES. These muscles are thick, flat and bandage-like and mainly support and concern with the motion of the head and neck as these parts of the body connect with the trunk. The splenius muscles are composed of two muscles- the splenius capitis and the splenius cervicis. Both arise from the NUCHAL LIGAMENT and the SPINOUS PROCESSES OF C7-T3 or T4 VERTEBRAE. The fibers of splenius capitis run superolaterally to the MASTOID PROCESS of the TEMPORAL BONE and the lateral third of the SUPERIOR NUCHAL LINE of OCCIPITAL bone. The muscle fibers of splenius cervicis insert to the tubercles of TRANSVERSE PROCESSES of C1-C3 or C4 vertebrae. When both splenii muscles act together, they extend the head and neck. When acting alone, it laterally flex the neck and rotate head to the side of active muscles.

In the above illustration it shows the spatial relationship of the splenius muscles. The splenius cervicis is located caudad to the splenius capitis. In terms of size and width of the splenius muscles, the splenius capitis is wider and bigger compared to the splenius cervicis. The above illustration also shows the relationship of the splenius muscles with the levator scapulae and the semispinalis capitis. The splenius muscles are anterior to the levator scapulae which are shown to be composed of 3 musculo-tendinous slips. However, the splenius muscles are more posterior to the semispinalis capitis muscles.

In the above illustration it shows the relationship of the splenius muscles with the serratus posterior superior. The splenius muscles lie deep to the serratus posterior superior. Or, it is more anterior to the serratus posterior superior.

The INTERMEDIATE LAYER OF INTRINSIC BACK MUSCLES are group together as the ERECTOR SPINAE ( SACROSPINALIS). These massive column of muscles are composed of 3 columns, namely from lateral to medial- ILIOCOSTALIS, LONGISSIMUS and the SPINALIS. The 3 columns of muscle arise by broad tendon from the posterior part of ILIAC CREST, posterior surface of SACRUM, the SACROILIAC LIGAMENTS, SACRAL and INFERIOR LUMBAR SPINOUS PROCESSES and the SUPRASPINOUS LIGAMENT. Each column is divided regionally into 3 parts according to its superior attachments (e.g., iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis). Although the muscle columns are generally identified as isolated muscles, each column is actually composed of many overlapping shorter fibers- a design that provides stability, localized action, and segmental vascular and neural supply. INSERTION: ILIOCOSTALIS (Lumborum, thoracis, and cervicis): fibers run superiorly to angles of the lower ribs and cervical transverse processes. LONGISSIMUS (thoracis, cervicis and capitis): fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone) SPINALIS (thoracis, cervicis and capitis): fibers run superiorly to spinous processes in upper thoracic region to the cranium. ACTION: Acting bilaterally, they extend the vertebral column and head; as back is flexed, these muscles control movement by gradually lengthening their fibers. Acting unilaterally, it laterally flex the vertebral column. All the muscles of the ERECTOR SPINAE are innervated by the posterior rami of the spinal nerves

The above slide shows the distinct division of the erector spinae muscles into columns. Although these columns are identified as isolated distinct muscles, these are actually made up of several short overlapping muscles that are inserted to individual segments of the ribs and transverse processes of the vertebral segments. These design provides greater stability of the spine, local/or segmental control, and segmental neural and vascular supply.

Each of the muscle columns are divided into 3 parts depending on the superior attachments of the muscle fiber. A. SPINALIS 1. Spinalis thoracis- medial continuation of the Erector Spinae, and is scarcely separable as a distinct muscle. It is situated at the medial side of the longissimus thoracis, and is intimately blended with it. It arises by 3 to 4 tendons from the spines of the 11th and 12th thoracic vertebrae, and first and 2nd lumbar vertebrae. These tendons uniting and form a small muscle which is inserted by separate tendons into the spines of the upper thoracic vertebrae, the number varying from 4 to 8. It is intimately united with the Semispinalis thoracis, which lie deep to it. 2. Spinalis cervicis is an inconstant muscle, which arises from the lower part of the ligamentum nuchae, the spine of the 7th cervical , and sometimes from the spines of the 1st and 2nd thoracic vertebrae. It is inserted into the spine of the axis, and occasionally into the spines of 2 cervical vertebrae below the axis. 3. Spinalis capitis: this is usually blended with the Semispinalis capitis B. LONGISSIMUS 1. Longissimus thoracis is the intermediate and largest of the continuations of the Erector spinae. In the lumbar region, where it is as yet blended with the Iliocostalis lumborum, some of its fibers are attached to the whole length of the posterior transverse processes and the accessory processes of the lumbar vertebrae, and to the middle layer of the thoracolumbar fascia. In the thoracic region it is inserted, by rounded tendons, into the tips of the transverse processes of all thoracic vertebrae, and by fleshy processes into the lower nine or ten ribs between their tubercles and angles. 2. Longissimus cervicis, situated medial to the longissimus thoracis, arises from the transverse processes of the upper 4 or 5 thoracic vertebrae and is inserted by similar tendons into the posterior tubercles of the transverse processes of the 2nd to 6th cervical vertebrae. 3. Longissimus capitis lies between the longissimus cervicis and Semispinalis capitis. It arises by tendons from the transverse processes of the upper 4 to 5 thoracic vertebrae, and the articular processes of the lower 3-4 cervical vertebrae, and is inserted into the posterior margin of the mastoid process deep to the Splenius capitis and the Sternocleidomastoid. C. ILIOCOSTALIS: As its name indicates, this lateral column of muscle arises from the iliac crest and inserts into the ribs. 1. Iliocostalis lumborum, inserting into the angles of the lower 6-7 ribs 2. Iliocostalis thoracis: arises from the lower 6th ribs and inserting into the angles of the upper 6 ribs and the transverse process of C7. 3. Iliocostalis cervicis: arises from the 3rd to 6th ribs and inserting into the transverse processes of C6 to C4.

The longissimus muscles in the lumbar region blend with the iliocostalis lumborum and are attached by tendinous slips to the whole length of the posterior transverse processes and accessory tubercles of the lumbar vertebrae and to the middle layer of the thoracolumbar fascia.

The Erector spinae muscle at the sacral region is narrow and pointed, and at its origin chiefly tendinous in structure. In the lumbar region it forms a thick fleshy mass which can readily be felt when palpated. The muscular fibers, which form a large fleshy mass, splits in the upper lumbar region into 3 columns. Generally the Erector spinae muscle is the chief extensor of the vertebral column if both sides act together. If one side of the muscle acts alone it bends the column to the same side of the muscle that acts on it. The Longissimus capitis acts not only as head extensor but also turns the head towards the same side.

The transverso-spinalis muscles are located in the space between the transverse processes and the spinous processes of the vertebral column. This collective space is called the gutter. As the name suggests, these muscles originate from the transverse process of the inferior vertebra then run superomedially and attach to the spinous processes of the vertebrae above.

The deep layer of intrinsic back muscles are found deep to the, ERECTOR SPINAE muscles. These are relatively short, obliquely directed group of muscles occupying the “gutter” between the collective transverse and spinous processes. These group of muscles are called the TRANSVERSOSPINALIS and, are composed of the SEMISPINALIS, MULTIFIDUS AND ROTATORES muscles. These muscles originate from the transverse processes of one vertebra below and pass to the spinous processes of more superior vertebrae. 1. The SEMISPINALIS is superficial in location and spanning 4-6 segments. As its name indicates, it arises from approximately half of the vertebral column. Collectively, it arises from the transverse processes of C4-T12 vertebrae. The fibers run superomedially to the occipital bone and spinous processes in the thoracic and cervical regions, spanning 4-6 segments. It is divided into 3 parts according to the vertebral level of their superior attachments. These consist of the semispinalis thoracis, semispinalis cervicis, and the semispinalis capitis. The semispinalis capitis and cervicis are more developed than the semispinalis thoracis. In general, each muscle , or main set of fibers within a muscle, crosses 6 to 8 intervertebral junctions. a. SEMISPINALIS CAPITIS: is responsible for the longitudinal bulge on each side in the back of the neck near the median plane. It lies deep to the splenius muscles. The muscle arises primarily from the transverse processes of the upper thoracic vertebrae. The muscle thickens superiorly and attaches to the occipital bone filling much of the area between the superior and inferior Nuchal lines. SEMISPINALIS CERVICIS: This muscle is much thicker and more developed than the semispinalis thoracis, attaches from the upper thoracic transverse processes to spinous processes of C2-C5. Muscle fibers that attach to the prominent spinous process of C2 are particularly well developed, serving as important stabilizers for the suboccipital muscles. b. SEMISPINALIS THORACIS : the fibers pass superomedially from the transverse processes to the spinous processes of more superior vertebrae. 2. The MULTIFIDUS consists of short, triangular muscular bundles that are thickest in the lumbar region. Each bundle passes obliquely superiorly and medially and attaches along the whole length of the spinous process of the adjacent superior vertebra. It arises from the posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of the erector spinae, sacroiliac ligaments, mamillary processes of the lumbar vertebrae, transverse processes of T1-T3 and the articular processes of C4-C7. 3. ROTATORES (BREVIS AND LONGUS): Best developed in the thoracic region. The deepest of the 3 layers of the TRANSVERSOSPINAL MUSCLES. They arise from the transverse process of one vertebra and insert into the root of the spinous processes of the next one or two vertebrae superiorly. As to their functions, the SEMISPINALIS extends the head, thoracic and cervical regions of the vertebral column and rotates them contralaterally. The MULTIFIDUS stabilizes vertebrae during local movements of the vertebral column. The ROTATORES stabilize the vertebrae and assist with local extension and rotatory movements of vertebral column. It may also function as organ of proprioception

The semispinalis muscles are divided into the following: 1. Semispinalis capitis; 2. Semispinalis cervicis; 3. Semispinalis thoracis. The first two are more developed than the semispinalis thoracis. The semispinalis capitis is the one responsible for the bulge at each side of the posterior neck near the median plane. It arises from the transverse processes of the upper thoracic vertebrae and travels superomedially to the occipital bone filling much of the space between the superior and inferior nuchal line.

The Multifidus muscles are more developed in the lumbar region. These are short triangular muscle bundles arising from the following: 1. Posterior surface of the sacrum 2. Posterior superior iliac spine 3. Aponeurosis of the erector spinae muscles 4. Sacroiliac ligaments 5. Mamillary process of the lumbar vertebrae 6. Transverse processes of T1-T3 7. Articular processes of C4-C7

The rotatores muscles are deepest layer of the transverso-spinalis muscles. These muscles are also the shortest of the three transverso-spinalis muscles. Although these muscles are found throughout the entire vertebral column, it is most developed in the thoracic vertebral region. By definition, the rotatores brevis muscle spans one vertebral junction; the rotatores longus spans two vertebral junctions.

These muscles lie deep to the transverso-spinalis muscles. The name “short segmental” refers to the extremely short length and highly segmented organization of muscles. These muscles exist throughout the vertebral column except for the thoracic region. These muscles are most developed in the cervical region, where fine control of the head and neck is so critical. The minor deep layer of intrinsic muscles are composed of the INTERSPINALES, INTERTRANSVERARII, AND THE LEVATORES COSTARUM. These muscles, which are the smallest of the deep back muscles, connect one vertebra to another. The INTERSPINALES AND THE INTERTRANSVERSARII are found at the cervical and the lumbar vertebrae. Each individual interspinalis and intertransversarus muscle crosses just one intervertebral junction. The LEVATORES COSTARUM are found from C7 vertebra to the 12 thoracic vertebrae. The INTERSPINALES originate from the superior surfaces of spinous processes of cervical and lumbar vertebrae and are inserted to the inferior surfaces of spinous processes of vertebrae superior to the vertebrae of origin. These muscles aid in extension and rotation of vertebral column. The INTERTRANSVERARII arise from the transverse processes of the cervical and the lumbar vertebrae ad inserted to the transverse process of adjacent vertebrae. These muscles aid in lateral flexion of vertebral column; acting bilaterally, they stabilize the vertebral column. The LEVATORES COSTARUM arise from the tips of transverse processes of C7 andT1-T11. Its fibers pass inferolaterally and insert on rib between its tubercle and angle. These muscles elevate ribs, assisting respiration; assisting with lateral flexion of vertebral column. The smaller muscles generally have higher densities of MUSCLE SPINDLES (sensors of proprioception- the sense of one’s position- that are interdigitated among the muscle fibers) than do large muscles. It has been presumed that this is because small muscles are used for the most precise movements or manipulation, and therefore require more proprioceptive feedback. The movements described for small muscles are assumed from the location of its attachments, the direction of the muscle fibers, and from activity measured by ELECTROMYOGRAPHY. Muscles such as the ROTATORES, INTERSPINALES, INTERTRANSVERSARII and LEVATORES COSTARUM are so small and are placed in positions of such relatively poor mechanical advantage that their ability to produce movements described is somewhat questionable. Furthermore such muscles often are redundant to other larger muscles having superior mechanical advantage. Hence, it has been proposed that the smaller muscles of small-large muscle pairs function more as “KINESIOLOGICAL MONITORS”- that is, organs of proprioception and that the larger muscles are the producers of motion. In spine surgery, these smaller muscles are destroyed without consideration to their function be this related to movement or to proprioception.

Each pair of interspinalis muscles is located on either side of, and often blends with, the corresponding interspinous ligament. The interspinales have a relatively favorable leverage and optimal fiber direction for producing extension torque. The magnitude of this torque is relatively small, however, considering the small size of the muscles. Each right and left pair of intertransversus muscle is located between adjacent transverse processes. As a group, the anatomy of the intertransversales is more complex than that of the interspinales. In the cervical region, for example, each intertransversus muscle is divided into small anterior and posterior muscles, between which pass the ventral rami of spinal nerves.

The musculature of the back are arranged in a series of layers. These muscles are grouped into: 1. the EXTRINSIC back muscles; 2. the INTRINSIC back muscles. The former group of muscles lie superficial to the latter. The extrinsic muscles are also called the “immigrant” muscles because these muscles are not originally located at the back. In the process of evolution when man assumed the erect position, the upper extremities are freed from the function of locomotion and become specialized organs of prehensile and these muscles found their way to the back where their mechanical advantage of leverage are better.

The VERTEBRAL COLUMN (or the spine), is the most important structure of the back. It extends from the cranium(skull) to the apex of the coccyx and forms the skeleton of the neck and back. It is the main part of the axial skeleton (articulated bones of the cranium, vertebral column, ribs and sternum. It functions as a partly rigid and flexible axis for the body and a pivot for the head, and; plays an important role in posture and locomotion . The adult vertebral column typically consists of 33 vertebrae arranged in 5 regions: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal. In adults the 5 sacral vertebrae are fused to form the SACRUM, and the 4 coccygeal vertebrae are fused to form the coccyx. The 24 vertebrae superior to the 1st sacral vertebra are called the PRESACRAL VERTEBRAE. Not everyone has 33 vertebrae, but the number of cervical vetebrae (7) is very constant in mammals including man. Even the giraffe has only 7 cervical vertebrae but they are long. However, variations occur in the number of thoracic, lumbar and sacral vertebrae in about 5% of normal human population. These differences in number can be either a change in one region (+ or -) without a change in other regions or a change in one region at the expense of another. In some people the 5th lumbar vertebra is partly or completely incorporated into the sacrum- a condition known as SACRALIZATION OF THE 5TH LUMBAR VERTEBRA; in others, the 1st sacral vertebra is separated from the sacrum and becomes the 6th lumbar vertebra- a condition known as LUMBARIZATION OF THE FIRST SACRAL VERTEBRA. The vertebrae gradually become larger as the vertebral column descends to the sacrum and then become progressively smaller toward the apex of the coccyx. These structural differences are related to the fact that the successive vertebrae bear increasing amounts of body weight. The vertebral column is flexible because it consists of small bones, the vertebrae, that are separated by the intervertebral discs. Significant motion occurs between only the superior 25 vertebrae. The twenty five(25) cervical, thoracic lumbar and 1st sacral vertebrae articulate at the SYNOVIAL ZYGAPOPHYSEAL joints, which facilitate and control the vertebral column’s flexibility. The vertebral bodies contribute approximately 75% of the height of the vertebral column, and the fibrocartilage of the intervertebral discs contribute approximately 25% of the height. The shape and strength of the vertebrae and intervertebral discs, ligaments and muscles provide stability to the vertebral column.

The spine is partly rigid to enable the body to maintain its erect position and to prevent the body from collapsing due to gravitational pull. It is a semi-rigid structure to serve as a pivot for the head and a weight bearing structure. The vertebral column is made up of series of small bones that is placed on top of each. However, the presence of joints in between these bones makes the vertebral column a very flexible structure. Grossly, the vertebral column is not a straight structure but assumes a shallow-S shaped. Such shape is akin to an accordion that permits greater flexibility. The flexibility of the vertebral column varies from one region to another. The cervical region is the most flexible and exhibits a wider range of motion. Such flexibility in the cervical vertebral column is related to the visual function. The flexibility in the thoracic region becomes less due to the presence of the thoracic cage. The lumbar region has the least flexibility. The vertebral bodies when combined account for the 75% of the height of the vertebral column while the intervertebral discs contribute 25% of the vertebral height.

The vertebral body ( the anterior, more massive part of the vertebra) gives strength to the vertebral column and supports the body weight. The size of the vertebral bodies, especially from T4 inferiorly, increase to bear the progressively greater body weight. In life most of the superior and inferior surfaces of the vertebral bodies are covered with HYALINE CARTILAGE, which are remnants of the cartilaginous model from which the bone develops, except at the periphery where there is a ring of smooth bone, the EPIPHYSEAL RIM. These cartilaginous remnants permit some diffusion of fluid between the intervertebral discs and capillaries in the vertebral body. The VERTEBRAL ARCH lies posterior to the vertebral body and is formed by right and left PEDICLES and LAMINAE. The PEDICLES are short, stout processes that join the vertebral arch to the vertebral body. The PEDICLES project posteriorly to meet 2 broad, flat plates of bone called the LAMINAE, which unite in the midline. The VERTEBRAL ARCH and the posterior surface of the vertebral body form the walls of the VERTEBRAL FORAMEN. In an articulated vertebral column the succession of the VERTEBRAL FORAMINA forms the VERTEBRAL CANAL, which contains the spinal cord, the meninges, fat, spinal nerve roots and vessels. The indentations formed by the projection of the body and articular processes superior and inferior of the pedicles are called the VERTEBRAL NOTCHES. The notch below the pedicle- the inferior vertebral notch, is usually larger than the superior vertebral notch. The superior and inferior vertebral notches of adjacent vertebrae contribute to the formation of the INTERVERTEBRAL FORAMINA., which give passage to the SPINAL NERVE and ACCOMPANYING VESSELS and contain the SPINAL(DORSAL ROOT) GANGLIA.

There are characteristic regional differences in the vertebrae which allow one to distinguish a cervical vertebra from a thoracic or lumbar vertebra or a thoracic from lumbar or cervical vertebra. However, only an expert can differentiate a fifth from a sixth thoracic vertebra. In the cervical region, the most distinctive feature is the presence of the TRANSVERSE FORAMEN (foramen transversarium) in each transverse process. In C7, the transverse foramina are smaller compared to the C1-C6. Occasionally, the transverse foramina in C7 are absent. The transverse foramina in the articulated cervical spine transmit the vertebral arteries except in C7 which only transmit small accessory vertebral veins. The spinous processes of cervical vertebrae C3-C6 are short and bifid with 2 knobs on their tips. Another characteristic is the almost equal sizes of their superior and inferior vertebral notches. C1, C2, and C7 are known as ATYPICAL CERVICAL VERTEBRAE. The first cervical vertebra (C1) is called the ATLAS. Because it supports the skull, it was named after ATLAS, who, according to the Greek mythology, supported the heavens. The ATLAS has no spinous process or body; it consists of anterior and posterior arches, each of which bears a tubercle and a lateral mass. Its kidney-shaped, concave, superior articular facets receive the OCCIPITAL CONDYLES of the skull. The 2nd cervical vertebra (C2), the AXIS, has a distinguishing blunt tooth-like structure known as the DENS, or, ODONTOID PROCESS. The 7th cervical vertebra is usually called the VERTEBRA PROMINENS because of its long spinous process which is conspicuous though the skin. It has also large transverse processes.

The cervical vertebrae are the smallest and most mobile of all movable vertebrae. This high degree of mobility is essential to the large range of motion required by the head in association with vision. The third to the sixth cervical vertebrae show nearly identical features and are therefore considered typical of this region. Note that the vertebral body gradually increases in size. In C7, it has already the characteristics of the thoracic vertebrae- long spine; the presence of costal facets for articulation with the ribs. The triangular-shaped vertebral canal is large in the cervical region in order to accommodate the thickening of the spinal cord associated with the formation of the cervical and brachial plexus. Within the C3-C6 region, consecutive superior and inferior articular processes form a continuous articular “Pillar” interrupted by apophyseal joints. The articular facets are oriented midway between the vertical and horizontal planes. The superior articular facets face posterior and superior, whereas the inferior articular facets face anterior and inferior.

All 12 thoracic vertebrae articulate with ribs; thus these vertebrae are provided for articular facets for rib articulations. There is one or more on each side of the body for articulation with the head of a rib and one on each transverse process of the upper 10 for the tubercle of the rib. The spinous processes tend to be long and slender, and those of the middle ones are directed downward over the vertebral arch of the vertebra below. The middle four thoracic vertebrae are typical. The shape of the body is heart-shaped and the vertebral foramina are circular. Sometimes an impression on the left side of the bodies is visible. It is produced by the descending aorta. The first four thoracic vertebra have some cervical features. The first thoracic vertebra differs from typical thoracic vertebrae in that it has an almost horizontal spinous process and long transverse processes. It has a complete costal facet on the superior edge of the body for the first rib and a demifacet on the inferior edge which contributes to the articular surface of the 2nd rib. The lower four thoracic vertebrae are atypical. They often have features of the lumbar vertebrae and possess mamillary, accessory, and lateral tubercles.

The lumbar vertebrae are characterized by their massive and large vertebral bodies compared to the cervical and thoracic vertebrae. Such massive vertebral body structure is attributed to the weight bearing function of the lumbar region.

The SACRUM is a large triangular, wedge-shaped bone that is usually composed of 5 fused sacral vertebrae. The word sacrum is a latin word meaning “sacred”, and provides strength and stability to the pelvis. It has 2 surfaces- the ventral and the dorsal surfaces and, are marked with 4 pairs foramina for the exit of the ANTERIOR AND POSTERIOR DIVISIONS of the SACRAL NERVES. The ventral (pelvic) foramina are larger than the dorsal foramina. Also the ventral surface of the sacrum is marked with TRANSVERSE LINES which indicate where fusion of the vertebrae occurred after the 20th year. The dorsal or posterior surface of the sacrum is rough, convex and marked by 5 prominent longitudinal ridges. The central one, the MEDIAN SACRAL CREST, represents the fused spinous processes of the upper sacral vertebrae. The intermediate crest represents the fused articular processes and the lateral crests represents portions of the transverse processes. The BASE OF THE SACRUM is formed by the superior surface of the first sacral vertebra. The superior articular processes that articulate with the inferior articular processes of L5 project upward from the base. This projecting anterior edge of the body of the first sacral vertebra is called the SACRAL PROMONTORY (L. PROMONTORIUM, mountain ridge). The sacrum supports the vertebral column and forms the posterior part of the pelvis. It is tilted so that it articulates with L5 at an angle, the LUMBOSACRAL ANGLE. The sacrum is often wider in proportion to length in the female than in the male, but the body of the first sacral vertebra is usually larger in males. Because the articular surface of the lateral aspect of the sacrum is like an auricle (L. external ear), it is called the AURICULAR SURFACE. This is where a synovial joint, the SACROILIAC JOINT, is located between the sacrum and the ilium. Note the inverted V-shaped opening on the dorsal surface of the sacrum- the SACRAL HIATUS. On each side of the sacral hiatus are projections called the SACRAL CORNUA.

The curvatures of the back as seen superficially are due to the curvatures of the spine. In adults, there are four curvatures- cervical, thoracic, lumbar and the sacral. The CERVICAL AND LUMBAR CURVATURES (LORDOSES) are concave posteriorly while the THORACIC AND SACRAL CURVATURES (KYPHOSES) are concave posteriorly. The curvatures provide additional flexibility (shock-absorbing resilience) to the vertebral column comparable to that of a spring and, augment the flexibility provided by the intervertebral discs. Although the flexibility provided by the intervertebral discs is passive and limited primarily by the zygapophysial (facet) joints and longitudinal ligaments, that provided by the curvatures is actively resisted by the contraction of muscle groups antagonistic to the movement.

The THORACIC AND SACRAL CURATURES are called primary curvatures and that these develop during the fetal period. These curvatures are retained throughout life as a consequence of differences in height between the anterior and posterior parts of the vertebrae.

Palpation of the neck is best performed with the subject in the prone or supine position, achieving optimum relaxation. Note first the concavity of the neck region posteriorly. The natural curvature of the cervical spine is with concavity backwards thus adding to the difficulty of palpation. With the subject lying prone, the forehead resting on the hands, the chin tucked in slightly and the neck straight,begin the palpation by finding the external occipital protuberance. Radiating laterally and upwards from the external occipital protuberance are the two superior nuchal lines. These are palpable in their central section on most people, but are difficult to trace more than a few centimeters laterally. Running inferiorly and under the back of the skull from the protuberance, the external occipital crest can be palpated, ending at a deep hollow, which is level with the tubercle of the atlas (not palpable). This hollow is bounded below by the large prominence of the spine of the AXIS; this is approximately 3 cm below the external occipital protuberance The spine is easy to find and can be used for the identification and location of other bony features. Below, the spines of C3, C4 and C5 are closely packed together due to the curvature of the spine at this point. The spine of C3 lies close under the spine of C2 and is therefore difficult to palpate, the spine of C4 often being mistaken for that of C3. As the palpation progresses to the lower part of the neck, there are two spinous processes can be palpated. These are closed together and rigid to touch. The lower of the two is the spine of the T1, that just above the spine of C7. The spine of C6 stands out clearly above that of C7 and can at times be mistaken for it. Differentiation of C6 and C7 can be carried out by asking the subject to extend the head and neck while keeping your finger on the spine of C6. It tends to move forward causing it to disappear from beneath the palpating finger, while the spine of C7 remains stationary. Just above the spine of C6, that of C5 is identifiable, being very closed to that of C4. It would be expected that flexion of the neck would improve identification. Unfortunately, except for the spines of C7 and T1, this is not the case as the tightening of the ligamentum nuchae hides the spines. The spines of C3, C4, C5 and C6, although difficult to identify separately, appear broad due to their bifid nature.

LATERAL ASPECT OF THE NECK: Although the transverse processes of the cervical vertebrae appear to project well out to the side, they are in fact quite difficult to palpate and identify. It is possible to palpate the tip of the transverse process of C1 between the angle of the mandible and the tip of the mastoid process. In some subjects the transverse process of C1 is not only palpable, but visible, as a small prominence. In others, it is difficult to identify even on deep palpation. This region can be quite tender if too much pressure is applied, and care must be taken to avoid the long and narrow styloid process. The other transverse processes, with the exception of C2, present a double point laterally, the anterior and posterior tubercles, but owing to the muscle attachments and fascial coverings they are not easy to distinguish.

The thoracic part of the vertebral column can only be palpated posteriorly, where it presents spines and transverse processes. However, these either overlap each other or are covered with strong, thick muscles and fascia, making it difficult to distinguish these structures with ease. The spines form a line of tubercles down the midline of the thorax. They are not uniform in length, but pass downwards with a tendency to overlap the spine below. Those near the upper part of the thorax have their tips level with the upper surface of the vertebral body below, while the lower half have longer spines which reach to the lower border of the vertebra below. The tip of the SPINE OF T3 is roughly level with the root of the spine of the scapula. The SPINE OF T12 is not typical, as it is squared posteriorly and resembles that of a lumbar vertebra; it is level with the disc of T12 and L1. The transverse processes are much more difficult to palpate as they are covered by strong, thick muscles even in the thinner subject. The tips of the transverse processes are level with the upper border of their own vertebral body. The lateral tips of the transverse processes lie 3 cms lateral and parallel to the spines. The tip of the spine, however, lies 1 cm below the level of the transverse processes of the vertebra below. This measurement remains constant because the shorter spines in the upper thorax are compensated for by the transverse processes of being slightly raised. Lateral to the tips of the transverse processes is a groove marking the line of the costotransverse joints.

To enable the back muscles to relax, the subject is best examined in a prone-lying position. Just lateral to the tip of each transverse process the posterior section of each rib can be palpated, being separated from the transverse process by a depression. With the subject’s arms hanging over the side of the couch( i.e., the pectoral girdle in protraction), find and trace the first to tenth ribs laterally. The RIB ANGLE lies approximately 3-4 cm lateral to the tips of the transverse processes and can be readily palpated in the mid-thoracic region, becoming less clear above and below. The first rib does not possess an angle and those of the 11th and the 12th ribs are slight if present. Each rib, together with the intercostal spaces above and below, can be traced anteriorly to where it joins the sternum. The 2nd to 7th or 8th ribs are usually hidden posterolaterally by the scapula, while the 11th and 12th ribs only exist posterolaterally. The first rib is the most difficult to palpate. It lies deep to the clavicle anteriorly, and deep to the trapezius and levator scapula. If deep pressure is applied immediately below the clavicle, 1 cm lateral to its medial end, the junction of the rib with the manubrium can be palpated. Above the middle of the clavicle in the supraclavicular fossa, it is possible, using deep pressure, to feel the lateral border of the first rib, but this area is particularly tender and may produce unpleasant reactions in the upper limb due to pressure on the trunks of the brachial plexus and subclavian artery.

A horizontal line joining the highest points of the iliac crests passes through the tip of the L4 spinous process and the L4-L5 intervertebral disc. This is a useful landmark in performing lumbar puncture to obtain a sample of cerebrospinal fluid(lumbar spinal puncture). The S2 spinous process lies at the middle of a line drawn between the posterior superior iliac spines, indicated by the skin dimples formed by the attachment of skin and deep fascia to these spines. These level indicates the inferior extent of the subarachnoid space (lumbar cistern). The median crest of the sacrum can be palpated in the midline inferior to the L5 spinous process. The SACRAL HIATUS can be palpated at the inferior end of the sacrum in the superior part of the INTERGLUTEAL (natal) CLEFT between the buttocks. Clinically the coccyx is examined with a gloved finger in the anal canal and its apex can be palpated approximately 2.5 cm posterosuperior to the anus. The SACRAL TRIANGLE is formed by the lines joining the posterior superior iliac spines and the superior part of the intergluteal cleft. The SACRAL TRIANGLE outlining the sacrum is a common area of pain resulting from low back sprains.

Posteriorly, the spines of the lumbar vertebrae project backwards and are individually identifiable. With the subject lying prone, place a firm pillow under the abdomen which flattens the lumbar lordosis. This makes the spines of the lumbar vertebrae become more pronounced, appearing as a line of flattened edges forming a crest down the center of the lumbar region. The spines are continuous with those of the sacrum below and the thoracic vertebrae above. Immediately above the central part of the sacrum is a hollow, due to the spine of the 5th vertebra being shorter and the body being situated slightly more anterior than the rest. The small gaps between the spines tend to disappear when the vertebral column is flexed, owing to the tension of the supraspinous ligament. If deep pressure is applied approximately 5 cm lateral to the vertebral spines, beyond the bulk of the erector spinae muscles, the tips of the transverse processes, particularly of the 1st lumbar vertebra, can be palpated. These are quite thin compared with those of the thorax and may be tender to palpate. THE SACRUM: The posterior surface of the sacrum can be identified between the posterior borders of the two ilia. Its lower section projects backwards and is easy to palpate, while its upper section (the base) lies more anterior and is more difficult to examine. It has a central, vertical series of spinous tubercles, in line with the lumbar spines and the coccyx, accompanied on either side by a row of articular tubercles which are all palpable. THE COCCYX: As this bone varies considerably in size and shape it may prove to be a little difficult to palpate. However, there are several alternative methods that can be employed: 1. Trace the spinous processes which run down the center of the posterior surface of the sacrum to approximately 2.5 cm below the level of the POSTERIOR INFERIOR ILIAC SPINE. Here, the pointed lower end of the coccyx can be palpated. 2. Gently run your fingers up the cleft between the two gluteus maximus muscles until the hard bony tip of the coccyx is found. 3. Draw and equilateral triangle with its base on the two posterior inferior iliac spines of the ilium with its apex downwards. This point should be on the tip of the coccyx. In many subjects, the coccyx is angled forwards and the finger must be pressed deep into the cleft to identify the shape. Care must be taken as pressure on the bone can cause pain, particularly if the joints between it and the sacrum have been damaged at any time.

The above radiograph is an antero-posterior projection of the cervical spine. It is taken either in upright or lying position in which the xray cassette is placed at the back of the neck and the xray directed antero-posteriorly. What is shown are the following: 1. vertebrae from C3 to T2. C1 and C2 are not shown due to the the opacity of the mandible which appears in the xray film as radiodense. 2. At the middle are rounded outline, the “tear drop” outline of the spinous process of the corresponding vertebra; the radiolucent outline representing the trachea. Such radiolucent outline is caused by the presence of air in the trachea. 3. Both lateral aspect of the cervical vertebrae are solid bony masses known as the lateral masses representing the articulating facets of the cervical spine. Both the superior and inferior articulating facets are outlined. 4. Further distally are the structures of the upper thoracic cage- the 1st to the 3rd thoracic ribs; the transverse processes of C3 to T3 5. Proximal 3rd of the clavicles. 4.

Above is a lateral view of the cervical spine. In this projection, the xray film or cassette is place on the side of the neck and the xray tube is in the opposite side. Take note of the following structures: 1. Odontoid process, or, the dens 2. Posterior arch of the Atlas 3. The vertebral bodies of the 2nd to the 7th cervical vertebrae 4. Intervertebral Discs from C2-C3 to C6-C7 5. The posterior spinous processes from C2 to C7 6. The zygapophyseal(facet) joints

Of clinical significance are the bony and soft tissue outlines of the different part of the cervical structures. These are the following: 1. The collective outline of the : a. anterior border of the vertebral bodies of cervical vertebrae b. the posterior border of the vertebral bodies of the cervical vertebrae c. The anterior border of the spinous processes of cervical vertebrae d. The distance between the inferior anterior corner of the superior vertebral body to the superior anterior corner of the vertebral body below 2. The distance between the anterior border of the cervical vertebral bodies to the anterior soft tissue shadow If a line is drawn connecting all the anterior borders of the cervical vertebrae a smooth curved line is outlined. This is also true to the posterior border vertebral bodies and the anterior outline of the spinous processes. The distance between the anterior border borders of the cervical vertebral bodies and the anterior soft tissue shadow are relatively constant. As shown above the distance between the anterior ring of the atlas and the anterior soft tissue shadow is about 10 mm. That of the anterior inferior corner of the 2nd cervical vertebra in relation to the anterior soft tissue shadow is 5 mm; at the level of the anterior inferior corner of C3 and superior anterior corner of C4 is 7 mm; at the level of the anterior inferior corner of C5 to C7 is 20 mm.

The bony and soft tissue outlines are used to diagnosed conditions like vertebral fractures involving the cervical spines. In the right side illustration, letter A shows a break in the outline of the anterior border of the spinous process at the level of C1. The anterior border of the posterior ring of the atlas is translated more anteriorly and the anterior ring, which is supposed to abut the odontoid process of C2, has moved more anteriorly. This means that the ligaments that hold the atlanto-odontoid joint are violated to permit subluxation of the atlas in relation to the odontoid process. In illustration shown in letter B, there is a breakage of the continuity of the outlines of the posterior border of the body and the anterior border of the spinous process at level of C2 with posterior translated of the odontoid process posteriorly without any disturbance of the relationship between C1 and C2. This means that there is fracture of the odontoid process with posterior displacement.

The illustration at the right side is a posteroanterior projection of the last 3 thoracic vertebrae. This is taken with the xray plate placed at the anterior part of the abdomen and the xray tube directed posteroanteriorly. The following parts are visualized: 1. at the middle are the teardrop structures representing the spinous processes of the 10th, 11th and 12th thoracic vertebrae 2. lateral to the spinous processes, at both sides are the outlines of the pedicles as indicated by the dots. 3. the ribs 4. the transverse processes: small faint structures dotting outside the vertebral bodies just below the ribs attachment to the vertebral bodies.

In the articulated vertebral column, each segment is connected to each other by series of joints to give enough flexibility and strength. These joints are symphyses-that is, secondary cartilaginous joints united by fibrocartilage, that allow movement between adjacent vertebrae. The articulating surfaces of two adjacent vertebrae are connected by INTERVERTEBRAL DISCS which are interposed between the bodies of adjacent vertebrae. At the vertebral arches, the ZYGAPOPHYSEAL (FACET) joints are formed by the articulation of the superior articulating processes of the lower vertebra with the inferior articulating processes of the superior adjacent vertebra.

The CRANIOVERTEBRAL JOINTS include the ATLANTO-OCCIPITAL JOINTS and the ATLANTOAXIAL JOINTS. These joints are SYNOVIAL in character and have no intervertebral discs. Their design allows a wider range of movements than the rest of the vertebral column. The ATLANTO-OCCIPITAL JOINTS , between the lateral masses of the ATLAS (C1) and the occipital condyles of the cranium, permit the following motions: flexion, extension, sideways tilting of the head, and rotation. The main movement is FLEXION, with a little lateral flexion (bending) and rotation. These joints are synovial joints of the condyloid type and have thin, loose joint capsules. The cranium and C1 are also connected by the anterior and posterior ATLANTO-OCCIPITAL MEMBRANES, which extend from the anterior and posterior arches of C1 to the anterior and posterior margins of the FORAMEN MAGNUM. The anterior and posterior atlanto-occipital membranes help prevent excessive movement of these joints.

There are 3 articulations that composed the ATLANTOAXIAL JOINTS- 2 (right and left) lateral atlantoaxial joints between the lateral masses of C1 and the superior facets of C2; 1 median atlantoaxial joint between the DENS of C2 and the ANTERIOR ARCH and the TRANSVERSE LIGAMENTS of the ATLAS. The median atlantoaxial joint is a PIVOT joint, whereas the lateral atlantoaxial joints are gliding type synovial joints. Movement at all three atlantoaxial joints permits the head to be turned from side to side, as occurs when rotating the head to indicate disapproval (the “NO” movement). During this movement, the cranium and C1 vertebra rotate on the C2 as one unit. During the rotation of the head, the DENS of C2 is the pivot, which is held in the socket formed anteriorly by the anterior arch of the atlas and posteriorly by the transverse ligament of the atlas. The TRANSVERSE LIGAMENT of the ATLAS is a strong band extending between the tubercles of the medial aspects of the lateral masses of the C1 vertebrae. Vertically oriented but much weaker superior and inferior longitudinal bands pass from the transverse ligaments to the occipital bone superiorly and to the body of C2 inferiorly. Together, the transverse ligament and the longitudina bands form the cruciate ligament(formerly called the CRURIFORM LIGAMENT), so named because of its resemblance to the cross. The ALAR LIGAMENTS extend from the sides of the dens to the lateral margins of the foramen magnum. These short, rounded cords attach the cranium to C1 vertebra and serve as a check ligaments, preventing excessive rotation at the joints. The TECTORIAL MEMBRANE is the strong superior continuation of the POSTERIOR LONGITUDINAL LIGAMENT across the median ATLANTOAXIAL joint through the foramen magnum to the central floor of the cranial cavity. It runs from the body of C2 to the internal surface of the occipital bone and covers the alar and transverse ligament.

At the cervical region from C3- C6, a distinctive joint is found at the lateral and posterolateral margin of the cervical intervertebral disc. This joint is called the UNCOVERTEBRAL JOINT OF LUSCHKA , and is formed by the UNCINATE PROCESSES of C3.-C6 and the bevelled inferolateral surfaces of the vertebral bodies superior to them. The uncovertebral joints of Luschka are only found in the cervical region and specifically at the level of C3 to C6 vertebrae.

The NUCLEUS PULPOSUS is a pulplike gel located in the mid posterior part of the disc. Consisting of 70% to 90% water, the nucleus pulposus functions as a modified shock absorber that dissipates and transfers loads between consecutive vertebrae. It is thickened by relatively large branching proteoglycans. Each proteoglycan is an aggregate of many water-binding glycosaminoglycans link to core protein. It also contains type II collagen fibers, elastic fibers and noncollagenous proteins The annulus fibrosus consists of 10 to 20 concentric layers, or rings of collagen fibers. Like dough surrounding jelly in a doughnut, the collagen rings encase and physically entrap the liquid-based central nucleus pulposus. The annulus fibrosus is thicker anteriorly than posteriorly. This difference in thickness is one of the anatomical reasons for the posterior direction of disc herniation. Compression force increases the hydrostatic pressure within the entrapped and water-logged nucleus pulposus. The increase in pressure absorbs shock across the interbody joint. The annulus fibrosus contains material similar to that found in the nucleus pulposus, differing only in proportion. In annulus fibrosus, collagen makes up about 50 to 60% of the dry weight, as compared with only 15 to 20% in the nucleus pulposus.

The intervertebral discs add considerable stability to the vertebral column, as well as being shock absorber. The stabilizing function of the disc is due primarily to the structural configuration of the collagen fibers within the annulus fibrosus. These collagen fibers are oriented in a precise geometric pattern. In the lumbar region, collagen rings lie about 65 degrees from the vertical, with fibers of adjacent layers travelling in opposite directions. This structural arrangements resists distraction (vertical separation), shear(sliding) and torsion (twisting). If the imbedded collagen fibers ran nearly vertical, the discs would resist distraction forces but not sliding or torsion . In contrast, if the fibers ran parallel to the top of the vertebral body, the disc would resist shear and torsional forces but not distraction forces. The 65-degree angle likely represents a geometric compromise that allows tensile resistance against the usual movements at the lumbar spine. Distraction forces are an inherent component of flexion, extension and lateral flexion, occurring as one vertebral body tips slightly and, therefore, separates relative to its neighboring vertebra. Shear and torsion forces are produced during virtually all movements of the vertebral column. Because of the alternating pattern of layering of the annulus fibrosus, only the collagen fibers oriented to the direction of the slide or twist become taut. Fibers in every other layer slacken.

The vertebral column is the primary support structure for the trunk and the neck, which, in turn, supports the head. Distally, however, the ground reaction forces are also exerting and transmitting loads to the vertebral column. Although highly dependent on the position of the spine, approximately 80% of the load across two lumbar vertebrae is carried through the interbody joint. The remaining 20% is carried by posterior structures, such as the apophyseal joints (facet joints) and the laminae. The intervertebral discs are uniquely designed as shock absorbers, protecting the bone from the compression forces produced by body weight and muscle contraction. Compression forces push the endplates inward and toward the nucleus pulposus. Being filled mostly with water and therefore essentially incompressible, the nucleus responds by deforming radially and outwardly against the annulus fibrosus. Radial deformation is resisted by the tension created within the stretched rings of the collagen and elastic fibers. Internal resistance reinforces the walls of the annulus fibrosus. As a result, back pressure is created against the nucleus pulposus and endplates, reinforcing the entire disc and passing the load to the next vertebra. When compressive force is removed from the endplates, the stretched elastic and collagen fibers return to their original preload length and prepare for another cycle of shock absorption. The disc provides little resistance to small compressive loads, but more resistance to large ones. The disc thereby allows flexibility at low loads and provides stability at high loads. The shock absorption mechanism protects the disc in 2 ways. First, compressive forces are diverted from the nucleus pulposus, toward the annulus fibrosus, and back to the nucleus and endplates. Such diversion takes time, thereby reducing the rate of loading, although not necessary the magnitude of the load. Second, the mechanism allows compressive forces to be shared by multiple structures, thereby limiting pressure on any single tissue.

The structure of the intervertebral disc changes with age. The older disc has less proteoglycan content and, therefore, less ability to attract, imbibed and retain water. The water content of the nucleus pulposus at birth is 88%, but decreases to 65 to 75% by the age of 75 years. The aged disc contains more collagen and less elastin, rendering it more fibrous and less resilient. A drier or more dessicated and less elastic nucleus pulposus is less able to cushion the vertebral body against excessive compression forces. As a result, the vertebral bodies and endplates may experience microfractures and bony resorption, ultimately leading to progressive and permanent age-related loss in height. The amount of loss is greater in person with severe OSTEOPOROSIS of the vertebral column and those with osteoporotic compression fractures, leading to an exaggerated kyphosis known as “widow’s hump”

Most HNPs occur posterolaterally or posteriorly. This usual direction of protusion of the nucleus pulposus is due to the fact that this side is relatively thin and does not receive any support from the posterior or anterior longitudinal ligament. Posterolateral herniation compresses the nerve root while central posterior herniation compresses the spinal cord. HNP is one of the major causes of back pain. However, not all back pain is caused by HNP. The percentage of persons with low back pain due to HNP is uncertain but likely significant. This condition has generated extensive research on methods of diagnosis, mechanisms of herniation, rehabilitation and efficacy of surgery.

Types of HNP: A. Protrusion: The displaced nucleus pulposus remains within the annulus fibrosus, but may create a pressure bulge on the spinal cord B. Prolapse: Displaced nucleus pulposus reaches the posterior edge of the disc, but remains confined within the outer layers of the annulus fibrosus. C. Extrusion: annulus fibrosus ruptures, allowing the nucleus pulposus to completely escape from the disc into the epidural space D. Sequestration: Parts of the nucleus pulposus and fragments of annulus fibrosus become lodged within the epidural space

In the causation of HNP, two mechanisms are typically involved. First, it involves a very large, sudden compression force that is being applied over the lumbar spine that is flexed or, most likely, flexed and axially rotated. This happens in an event like falling from a height and landing on the buttocks or; in lifting a large load. In this situation, a flexed and/or twisted lumbar spine renders the disc mechanically vulnerable to protrusion. A flexed spine stretches or thins the posterior side of the annulus fibrosus as the nuclear gel is forced posteriorly, often under large hydrostatic pressure. This amount of hydrostatic pressure increases with greater trunk muscle activation, usually in response to large external torques. With sufficiently high hydrostatic pressure, the nuclear gel creates or finds a preexisting fissure in the posterior annulus. A partially rotated spine renders only half the posterior fibers of the annulus taut, thereby reducing the potential resistance that can be applied against approaching nuclear gel. The second mechanism involves a series of multiple, low magnitude compression forces, often imposed over a flexed lumbar spine. This mechanism of prolapse generally occurs gradually from cumulative microtrauma, such as that which may occur from many years of repetitive lifting or bending with an excessively flexed back.

Despite the abundance of literature and anecdotal evidence, a single unifying cause-and-effect explanation for all forms of disc herniation is lacking. The four factors listed above are particularly important. Disc prolapse can occur even in the absence of trauma or mechanical overload. A habitual chronic sitting posture involving a rounded and flexed lumbar posture certainly may predispose a person to posterior migration of the nucleus pulposus. A chronically flexed lumbar posture may, in time, overstretch the posterior part of the annulus to a point where it is unable to resist a potent hyperflexion-induced posterior migration of the nucleus. This explanation, however, is subject to scrutiny because the incidence of disc prolapse in the lumbar region is very low in culture whose people habitually squat with near maximal flexed lumbar spines. The healthy lumbar disc with intact annulus fibrosus is remarkably resistant to disc herniation, even from a large flexion force. The reason for the relatively high incidence of disc prolapse in western culture is still not fully understood.

The above illustration shows to different positions of the lumbar vertebral column. At the left, the motion is exemplified by the anterior pelvic tilt. This maneuver causes extension of the lumbar vertebral region and increases the lumbar lordosis. This motion exerts pressure at the posterior aspect of the intervertebral disc and causes an anterior shift to the nucleus pulposus away from the spinal nerve exiting from the corresponding intervertebral foramen. Take note that this maneuver also decreases the diameter of the intervertebral foramen. On the other hand, the illustration at the right side shows a sitting position that decreases the lumbar lordosis producing a round back and flexed lumbar region. This position exerts pressure at the anterior part of the intervertebral disc and causes posterior migration of the nucleus pulposus. It is postulated that a habitual posture that produces rounded back and flexed lumbar vertebral region may, in time, cause overstretching of the ligaments at the posterior aspect of the intervertebral disc. Such overstretching renders the posterior aspect of the intervertebral disc vulnerable to a sudden compressive flexion force acting on the lumbar vertebral region. This flexion compression force, though lesser in magnitude, causes rupture of the intervertebral disc and herniation of the nucleus pulposus. Take note that flexion of the lumbar vertebral region increases the intervertebral foramen. While it gives a lot of space for the spinal nerve, it does not give any resistance to an herniating nucleus pulposus.

The major stabilizing ligaments of the spine are: 1. LIGAMENTUM FLAVUM 2. ANTERIOR LONGITUDINAL LIGAMENT 3. POSTERIOR LONGITUDINAL LIGAMENT 4. SUPRASPINOUS AND INTERSPINOUS LIGAMENT 5. INTERTRANSVERSE LIGAMENT

The vertebral column is supported by an extensive set of ligaments. Spinal ligaments limit motion, maintain natural spinal curvature, and indirectly protect the spinal cord. The ligamentum flavum means “the yellow ligament” reflecting its high content of yellow elastic connective tissue. It originates on the anterior surface of a lamina and inserts on the posterior surface of the lamina below. The ligaments are thickest in the lumbar region. Passive tension in a series of stretched ligamentum flava limits flexion throughout the vertebral column, thereby protecting the intervertebral disc from excessive compression. The ligamentum flava is the most elastic ligament of the spine and is “PRE-TENSIONED”(possessed tension at rest) when the spine is at neutral position.

The above illustration shows the stress/strain curved of the ligamentum flavum in relation to flexion-extension of a spinal segment. From a neutral extension to full flexion there is increase in tension(stress) and the ligamentum flavum has elongated(strain) 35% of its original resting length. Flexion beyond physiologic limits can rupture the ligament and permit compressive damage to the intervertebral disc. The ligamentum flavum lies just posterior to the spinal cord. Severe hyperextension of the spine can buckle the ligamentum flavum inward and can pinch the delicate spinal cord.

The SUPRASPINOUS AND INTERSPINOUS LIGAMENTS are attached between the adjacent spinous processes from C7 to the sacrum. These ligaments function to limit flexion of the vertebral column. In the craniocervical region, the supraspinous ligament becomes the LIGAMENTUM NUCHAE which provides a midline structure for muscle attachments, and passive support for the head.

The anterior longitudinal ligament is a long, straplike structure attaching between the basilar part of the occipital bone and the entire length of the anterior surface of all vertebral bodies including the sacrum where it merges with the SACROILIAC JOINT CAPSULE. This strong ligament is narrow at its cranial end and widens caudally. It has two sets of fibers- superficial and deep fibers. The superficial fibers span the vertebral segments; the deep fibers blend with the annulus fibrosus and reinforce it. It provides axial stability to the vertebral column by limiting extension or excessive lordosis in the cervical and lumbar regions.

The INTERTRANSVERSE LIGAMENT are attached in between adjacent transverse processes and functions to limit contralateral flexion. It is well-developed in the thoracic region while only few fibers exist in the cervical region. In the lumbar region, these ligaments are thin and membranous.

The posterior longitudinal ligament is a continuous band of ligament that extends the entire length of the posterior surfaces of all vertebral bodies between the axis(C1) and the sacrum. It is located within the vertebral canal, just anterior to the spinal cord. The posterior and anterior longitudinal ligaments are named according to their relationship to the vertebral body ,not the spinal cord. Throughout its length, the posterior longitudinal blends with and reinforces the intervertebral discs. Cranially, this ligament is a broad structure, and then narrowing as it descends toward the lumbar region. The slender lumbar region limits its ability to restrain a posterior bulging(slipped) disc. This ligament provide axial stability to the spine.

The arrangement or the architecture of the intrinsic muscles of the back is akin or like that of a bridge in which a big, long steel cable with huge diameter span the entire bridge. While smaller cables span each segment of the bridge. To stabilize the whole length of the vertebral column, the intermediate layer of the intrinsic muscles, the ERECTOR SPINAE, span the entire length of the vertebral column from the pelvis to the cranium. The ERECTOR SPINAE are composed of 3 massive column of muscles that originate from massive bony structures of the pelvis, the lumbar spines and from the thoracolumbar fascia. On the other hand, each spinal segment are supported by smaller types of muscles. These muscles constitute the DYNAMIC STABILIZERS of the vertebral column.

The joint capsules surround and reinforce each apophyseal joint. The capsule is relatively loose, especially in the cervical region where ample range of motion is required. Although relatively loose in a neutral posture, the capsule of the apophyseal joint is under tension when stretched. In the lumbar region, the capsule is shown to accommodate up to 1000 N (approx. 225 lb) of tension before failure. The tension limits the exremes of all intervertebral motions with the exception of extension. The capsules of the apophyseal joints is reinforced by the adjacent muscles(MULTIFIDUS) and connective tissue (LIGAMENTUM FLAVUM), particularly evident in the lumbar region

The connective tissues that surround the vertebral column limit extremes of motion. By restricting motion. Connective tissues- including those within muscle- help protect the delicate spinal cord and maintain optimal posture

In the cervical region, the presence of structures like the trachea and esophagus also limit cervical extension. The anterior part of the annulus fibrosus and anterior longitudinal ligament are the consistent connective tissues that limit extension of the vertebral column

In most, if not all vertebral motions the ANNULUS FIBROSUS is the most consistent structure that limits motion of the vertebral column. This is followed by the capsule of the apophyseal joints.

In cases of trauma or overuse, biologic tissues may generate excessive tension as a means to protect an injured vertebral segment. Spasm in local muscles following acceleration-deceleration (“whiplash”) injury of the neck is a common expression of this protective guarding. In cases of disease, such as severe rheumatoid disease, limited spinal mobility has no protective function, but is instead an intrinsic part of the pathologic process.

The typical INTERVERTEBRAL JUNCTION is the segment of the vertebral column where the articulating joints are found. It is, therefore, the seat of vertebral movements. Motion in one intervertebral junction is actually very limited but the summation of movements in the 25 moving vertebrae is translated into significant range of vertebral motion in the different anatomic planes

The INTERVERTEBRAL JUNCTION is composed of 3 parts: 1. the SPINOUS PROCESS AND THE TRANSVERSE PROCESSES; 2. THE APOPHYSEAL JOINTS; 3. THE INTERBODY JOINT. All three share common functions, although each has predominant function.

The spinous and transverse processes are sites of attachments for muscles and ligaments. These bony structures act as OUTRIGGERS, or LEVERS, providing and increasing the mechanical advantage of muscles and ligaments for the purpose of causing and restricting movements, and stabilizing the vertebral column.

The APOPHYSEAL JOINTS are primarily responsible for guiding intervertebral motion, much like the train tracks guide the direction of the train. The following factors greatly influence the direction of intervertebral motion: 1. geometry of the articular facets, 2. size, 3. spatial orientation of the articular facets The vertebral column contains 24 pairs of apophyseal joints. Each apophyseal joint is formed by the articulation between opposing facet surfaces. Mechanically, these joints are classified as plane joints. Although exceptions and natural variations are common, the articular surfaces of most apophyseal joints are flat. Slightly curved joint surfaces are present primarily in the upper cervical and throughout the lumbar spines. The word “apophysis” means bony “outgrowth” illustrating the protruding nature of the articular processes.

Acting as mechanical barricades, the apophyseal joints permit certain movements and block others. The orientation of the plane of the facet surface within each joint influences the kinematics at different regions of the vertebral column. As a general rule, horizontal facet surfaces favor axial rotation, whereas vertical facet surfaces (in either sagittal or frontal planes) block axial rotation. Most apophyseal joint surfaces, however, are oriented somewhat between the horizontal and vertical. The above illustration shows the typical joint orientation for articular facets in the cervical, thoracic and lumbar region. The plane of the facet surfaces explains, in part, why axial rotation is far greater in the cervical than in the lumbar region. Additional factors that influence the predominant motion at each spinal region includes the ff: 1. the sizes of the intervertebral discs, 2. shapes of the vertebrae, 3. local muscle actions, 4. attachments of the ribs and ligaments. The plane of the facet surfaces explains, in part, why axial rotation is far greater in the cervical region than in the lumbar region. Additional factors that influence the predominant motion at each spinal region include the sizes of the intervertebral discs, shapes of the vertebrae, local muscle action and attachment of the ribs or ligaments.

The INTERBODY JOINT functions primarily for shock absorption and load distribution. In addition, it adds stability between the vertebrae, serves as the approximate site of the axes of rotation, and functions as a DEFORMABLE INTERVERTEBRAL SPACER. As spacers, the intervertebral discs constitute 25% of the total height of the vertebral column. The larger the ratio between the height of the body and the height of the disc, the greater the relative movement between consecutive bodies. The greatest space between vertebrae occurs in the cervical and lumbar regions

The INTERBODY JOINT also demonstrate the spatial relationship of the neural tissue, the hard bony tissues, and the joint tissues. The delicate neural tissue is enclosed in a very rigid bony structure in a limited space. Since the vertebral column is composed of several segments that allow motion of considerable degree, the joints are also within the immediate vicinity of the neural tissue.

Normal interaction of all 3 parts of the intervertebral junction is required for normal vertebral movement. Mechanical dysfunction in any part can cause articular derangement and/ or impingement of the neural tissues. Understanding the spatial relationships between the neurology, osteology, and arthrology of the vertebral column is an essential element in understanding the cause and treatment of spinal pain and dysfunction, regardless of etiology. In the above illustration,a healthy intervertebral disc at C2-C3 and the uncovertebral joint of Luschka leave C3 spinal nerve undisturbed. Contrary to the IV disc at C3-C4 which is degenerate- that is, the IV disc is dessicated leading to loss of the intervertebral joint space height. The uncovertebral joint of Luschka is destroyed leading to the formation of bony spurs which encroaches into the intervertebral foramen thereby compressing the C4 spinal nerve.

The spatial relationship between the bony, soft tissue(spinal nerve) and the joint can be affected by motion (like flexion) as shown by the above illustration. In the neutral position, the facet surfaces within the apophyseal joint are in maximal contact. The size of the intervertebral foramen relative to the circumference of the existing nerve is indicated in red. In full flexion, the contact between the articular surfaces of the facet joint are becomes reduced. However, the opening for the passage of the nerve is increased several times.

As shown in the above illustration lumbar extension generates compression force in the intervertebral junction causing an inferior articular facet to move closer to its partner facet which is the superior articular facet of the lower vertebra. This motion is exemplified by a manuever called the anterior pelvic tilt. This manuever extends the lumbar spine and increases the lumbar lordosis. This action tends to shift the nucleus pulposus anteriorly and reduces the diameter of the intervertebral foramen.

This section deals with the study of the structures within the vertebral canal and its extensions through the intervertebral canal. These structures are the following: 1. Spinal Cord and its blood vessels 2. Spinal nerves, spinal roots, spinal rami 3. Meninges or the theca and its spaces, cerebrospinal fluid

The spinal cord is a continuation of the Medulla Oblongata which is distal part of the brainstem. It is approximately cylindrical structure that is flattened anteriorly and posteriorly, and occupies the superior 2/3 of the vertebral canal. The upper limit is located at the level of the upper border of the ATLAS; the lower end is located at the junction of the L1 and L2 vertebrae. The lower level varies, and there are normal variations especially in females. The lower end may be as high as the caudal third of the 12th thoracic vertebrae or as low as the disc between the 2nd and 3rd lumbar vertebrae.

The spinal cord, spinal meninges, spinal nerve roots, and neurovascular structures that supply them are in the VERTEBRAL CANAL. The spinal cord, the major reflex center and conduction pathway between the body and the brain, is a cylindrical structure that is slightly flattened anteriorly and posteriorly. It is protected by the vertebrae and their associated ligaments and muscles, the spinal meninges and the CSF. The spinal cord begins as a continuation of the medulla oblongata, the caudal part of the brainstem. In the newborn, the inferior end of the spinal cord usually is opposite the IV disc between L2 and L3 vertebrae. In adults, the spinal cord usually ends opposite the IV disc between L1 and L2 vertebrae; however it tapering end, the CONUS MEDULLARIS, may terminate as high as T12 or as low as L3. Thus the spinal cord occupies only the superior 2/3 of the vertebral canal. In adults, the spinal cord is shorter than the vertebral column; hence there is a progressive obliquity of the spinal nerve roots as the cord descends. Because of the increasing distance between the spinal cord segments and the corresponding vertebra, the length of the nerve roots increases progressively as the inferior end of the vertebral column is approached. The lumbar and the sacral rootlets are the longest. They descend until they reach the IV foramina of exit in the lumbar and sacral regions of the vertebral column respectively. The bundle of spinal nerve roots in the lumbar cistern (subarachnoid space) within the vertebral canal caudal to the termination of the spinal cord resembles a horse’s tail, hence the name CAUDA EQUINA. The inferior end of the spinal cord has a conical shape and tapers into the MEDULLARY CONE(L. conus medullaris). From its inferior end, TERMINAL FILUM(L. filum terminale) descends among the spinal nerve roots of the cauda equina. It consist s primarily of PIA MATER but its proximal end also includes vestiges of neural tissue, connective tissue, and neuroglial tissue. The terminal filum takes on layers of arachnoid and dura mater as it penetrates the inferior end of the dural sac and passes through the sacral hiatus to attach ultimately to the coccyx posteriorly. The terminal filum serves as an anchor for the end of the dural sac, the continuation of the dura inferior to the medullary cone. The spinal cord is enlarged in two regions for innervation of the limbs: -The CERVICAL ENLARGEMENT extends from the C4 through the T1 segments of the spinal cord and most of the anterior rami of the spinal nerves arising from it form the BRACHIAL PLEXUS of nerves, which innervates the upper limbs. The BRACHIAL PLEXUS is a major network of nerves supplying the upper limb. It is formed by the union of the ANTERIOR RAMI of C1-T1 nerves, which constitute the roots of the plexus. -LUMBOSACRAL (LUMBAR) ENLARGEMENT extends from the L1 through the S3 segments of the spinal cord, and the anterior rami of the spinal nerves arising from it constitute the LUMBAR and SACRAL plexuses of nerves which innervates the lower limb. The spinal nerve roots arising from the lumbosacral enlargement and the medullary cone form the CAUDA EQUINA, the bundle of spinal nerve roots running through the LUMBAR CISTERN(SUBARACHNOID SPACE). A total of 31 pairs of spinal nerves are attached to the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.

The cervical enlargement is the source of the large spinal nerves that supply the upper limbs. It extends from the third cervical to the second thoracic segments. Most of these spinal nerves contribute to the BRACHIAL PLEXUS which innervates the upper limb. The lumbar enlargement corresponds to the innervation of the lower limb. It extends from the first lumbar vertebra to the third sacral segments. Most of large spinal nerves from this lumbar enlargement composed the LUMBO-SACRAL PLEXUS.

The SPINAL MENINGES, or the THECA, are composed of the DURA MATER, ARACHNOID MATER, AND PIA MATER. These membranes and the CSF(CEREBROSPINAL FLUID) support and protect the spinal cord and spinal nerve roots, including those in the cauda equina. The DURA MATER is composed of tough fibrous and some elastic tissues. It is the outermost covering membrane of the spinal cord. A potential space separates the dura mater from the vertebrae. This space is called the EPIDURAL SPACE. The dura forms the spinal dural sac, a long tubular sheath within the vertebral canal. This long tubular sac adheres to the margin of the FORAMEN MAGNUM, where it is continuous with the cranial dura mater. Along the length of the vertebral canal the dural sac is pierced by the spinal nerves. At the distal end, the dural sac is anchored inferiorly by the TERMINAL FILUM. Laterally, the dural sac extends into the intervertebral foramina and enclosing the posterior and anterior nerve roots distal to the spinal ganglia to form the DURAL ROOT SHEATHS, or sleeves. These sheaths blend with the epineurium(outer connective tissue covering the spinal nerves that adhere to the periosteum lining the intervertebral foramina.

The DURA MATER forms a tube whose upper end is attached to the edge of the foramen magnum and to the posterior surfaces of the 2nd and 3rd cervical bodies, and also by fibrous bands to the posterior longitudinal ligament. Throughout the length to its distal portion, this attachment of the dura mater to the posterior longitudinal ligament is maintained. The dural tube narrows at the lower border of the 2nd sacral vertebra. It invest the filum terminale, descends to the back of the coccyx, and blends with the periosteum. EPIDURAL SPACE: It lies between the spinal dura mater and the tissues which line the vertebral canal. It is closed above by the fusion of the spinal dura with the edge of the foramen magnum, and below by the posterior sacrococcygeal ligament closes the sacral hiatus. It contains the following: 1. loosely pack connective tissue; 2. fat; 3. a venous plexus; 4. arterial branches; 5. lymphatics; 6. fine fibrous bands with connect the theca with the lining tissue of the vertebral canal. These fibrous band, known as MENINGOVERTEBRAL LIGAMENTS, are best developed anteriorly and laterally. Similar bands tether the nerve root sheath or “sleeves” within their canals. There is also a midline attachment from the posterior spinal dura to the LIGAMENTUM NUCHAE at the ATLANTO-OCCIPITAL and ATLANTO-AXIAL levels. The venous plexus consists longitudinally arranged chains of vessels, connected by circumdural venous rings. The anteriorly placed vessels receive the BASIVERTEBRAL VEINS. The shape of the epidural space within each spinal segment is not uniform. In the lumbar region the DURA MATER is apposed to the walls of the vertebral canal anteriorly and attached by connective tissue in a manner that permits the displacement of the dural sac during movement and venous engorgement. Adipose tissue is present posteriorly in recesses between the LIGAMENTUM FLAVUM and the DURA. The dura mater extends for a short distance through the intervertebral foramina along the sheaths of the spinal nerves. Like the main thecal sac, the root sheaths are partially tethered to the walls of the foramina by the fine meningovertebral ligaments. CLINICAL CORRELATION: Contrast media, anesthetics and other fluids injected into the epidural space at the sacral level may spread up to the cranial base. Local anesthetics injected near the spinal nerves, just outside the intervertebral foramina, may spread down or up the epidural space to affect the adjacent spinal nerves or may pass to the opposite side. SUBDURAL SPACE: A potential space in the normal spine because the ARACHNOID and DURA are closely apposed. It does not connect with the SUBARACHNOID SPACE, but continues for a short distance along the cranial and spinal nerves. Accidental subdural catheterization may occur during extradural injections. Injection of fluid into the subdural space may either damage the cord by direct toxic effects or by compression of the vasculature. The ARACHNOID MATER: This surrounds the spinal cord and is continuous with the cranial arachnoid mater. It is closely applied to the deep aspect of the dura mater. At sites where vessels and nerves enter or leave the subarachnoid space, the arachnoid mater is reflected on to the surface of these structures and forms a thin coating of leptomeningeal cells over the surface of both vessels and nerves. Thus a subarachnoid angle is formed as nerves pass through the dura into the intervertebral foramina. At this point, the layers of leptomeninges fuse and become continuous with the perineurium. The epineurium is in continuity of the dura. Such an arrangement seals the subarachnoid space so that particulate matter does not pass directly from the subarachnoid space into nerves. PIA MATER: It closely invests the surface of the spinal cord and passes into the anterior median fissure. As in the cranial region, there is a subpial “space”, however, over the space of the spinal cord the subpial collagenous layer is thicker than in the cerebral region, and it is continuous with the collagenous core of the ligamentum denticulatum. The LIGAMENTUM DENTICULATUM is a flat, fibrous sheet which lies on each side of the spinal cord in between the ventral and the dorsal nerve roots. Its medial border is continuous with the subpial connective tissue of the cord and its lateral border forms a series of triangular processes, the apices of which are fixed at intervals to the dura mater. There are usually 21 processes on each side. The first of the denticulate ligaments crosses behind the vertebral artery where it is attached to the dura mater, and is separated by the artery from the first cervical ventral root. Its site of attachment to the dura mater is above the rim of the foramen magnum, just behind the hypoglossal nerve; the spinal accessory nerve ascends on it posterior aspect. The last of the denticulate ligaments lies between the exiting 12th thoracic and 1st lumbar spinal nerves and is a narrow, oblique bands which descends laterally from the conus medullaris Beyond the conus medullaris the PIA MATER continues as a coating of the filum terminale. INTERMEDIATE LAYER: Aside from the well-defined 3 layers, the spinal cord is surrounded by an extensive INTERMEDIATE LAYER of leptomeninges. This particular layer is concentrated on the dorsal and ventral regions and forms a highly perforated, almost lace-like structure which is locally compacted to form the dorsal, dorsolateral and ventral ligaments of the spinal cord. This intermediate layer of leptomeninges around the spinal cord may act as a baffle within the subarachnoid space to dampen waves of CSF in the spinal column. Inflammation within the spinal subarachnoid space may result in extensive fibrosis within the INTERMEDIATE LAYER and the complications of CHRONIC ARACHNOIDITIS.

The SPINAL ARACHNOID MATER is a delicate, avascular membrane composed of fibrous and elastic tissue that lines the dural sac and the dural root sheaths. It encloses the CSF-filled SUBARACHNOID SPACE containing the spinal cord, spinal nerve roots, and spinal ganglia. The arachnoid mater is not attached to the dura but is held against the inner surface of the dura by the pressure of the CSF. In a LUMBAR SPINAL PUNCTURE, the needle traverses the dura and the arachnoid mater simultaneously. Their apposition is called the dura-arachnoid interface. No actual space occurs naturally at this interface. It is just a potential space. The arachnoid mater is separated from the pia mater by the SUBARACHNOID SPACE which is filled with CSF. Delicate strands of connective tissue, the ARACHNOID TRABECULAE, span the subarahnoid space connecting the arachnoid and pia mater. The SPINAL PIA MATER, the innermost covering membrane of the spinal cord, consists of flattened cells with long, equally flattened processes that follow all the surface features of the spinal cord. It also directly covers the roots of the spinal nerves and spinal blood vessels. Inferior to the medullary cone, the pia continues as the FILUM TERMINALE. The spinal cord is suspended in the dural sac by the terminal filum and especially by the RIGHT AND LEFT sawtooth DENTICULATE LIGAMENTS, which run longitudinally along each side of the spinal cord. These ligaments consist of a fibrous sheet of pia mater extending midway between the posterior and anterior nerve roots. Between 20 and 22 of these processes, shaped much like shark’s teeth, attached to the internal surface of the arachnoid-lined dural sac. The superior processes(uppermost part) of the right and left denticulate ligament attach to the cranial dura mater immediately superior to the foramen magnum. The inferior process extends from the medullary cone, passing between the T12 and L1 nerve roots.

The SUBARACHNOID SPACE is an actual space containing the CSF and lies between the arachnoid and pia mater. Inferiorly there is an enlargement of the subarachnoid space in the dural sac caudal to the medullary cone and the CAUDA EQUINA. This enlargement is called the LUMBAR CISTERN. The inferior extent of the lumbar cistern is at the level of S2.

To obtain a sample of CSf from the lumbar cistern, a lumbar puncture needle(or spinal needle), fitted with stylet, is inserted into the subarachnoid space. Lumbar spinal puncture is performed with the patient leaning forward or lying on the side with the backed flexed. Flexion of the vertebral column facilitates insertion of the needle by stretching the ligamentum flavum and spreading the laminae and spinous processes apart. Under aseptic condition the needle is inserted between the spinous processes of the L3 and L4 (or the L4 and L5) vertebrae. At these levels in adult, there is little danger of damaging the spinal cord. An anesthetic agent can be injected into the extradural(epidural) space using the position described in Lumbar Spinal puncture. The anesthetic agent has a direct effect on the spinal nerve roots of the cauda equina after they exit from the dural sac. The patient loses sensation inferior to the level of the block An anesthetic agent can also be injected into the extradural space in the sacral canal- A CAUDAL EPIDURAL BLOCK. The agent spreads superiorly and acts on the spinal nerves(caudal analgesia). The distance the agent ascends( and hence the number of nerves affected) depends on the amount injected and on the position assumed by the patient.

The introduction of contrast media (usually made up of iodinated compounds) into the subarachnoid space to outline the spinal cord and its components like the spinal nerves is called myelogram. It is used to diagnosed conditions like herniated nucleus pulposus, intravertebral canal tumors, effect of spinal fractures on the adjacent spinal cord. Several years ago, these iodinated compounds are oil based and are hardly re-absorbed and remain in the subarachnoid space for a long time. However, these oil-based iodinated compounds cause so much inflammation of the spinal meninges leading to paralysis of the patient. In other patients, these iodinated compounds rapidly transit proximally and cause respiratory paralysis. Most of these oil-based iodinated compounds are replaced by the water-based iodinated compounds.

The CEREBROSPINAL FLUID is a clear, colorless fluid that is actively secreted by the choroid plexuses in the lateral, 3rd and 4th ventricles of the brain. A total volume of CSF is 150 ml, of which 25 ml is located mostly in the lateral ventricles; 100 ml in the cranial subarachnoid space; the rest is located in the spinal subarachnoid space. The CSF is secreted at a rate of 0.35-0.40 ml per minute, which means that normally 50% of the total volume of CSF is replaced every 5 to 6 hours.

The spinal nerves are united ventral and dorsal spinal roots, attached in series to the sides of the spinal cord. The term ‘spinal nerve’ strictly applies to the short segment after union of the roots and before branching occurs. This segment, the spinal nerve proper , lies in the intervertebral foramen. At thoracic, lumbar, sacral and coccygeal levels the numbered nerve exits the corresponding vertebral canal Example, L4 nerve exits the intervertebral foramen between L4 and L5. However, in the cervical region, nerves C1 to C7 pass above their corresponding vertebrae. C1 leaves the vertebral canal between the occipital bone and atlas and hence is often termed the SUBOCCIPITAL NERVE. The last pair of cervical nerves (C8) do not have a correspondingly numbered vertebra. C8 passes between the 7th cervical and 1st thoracic vertebrae. Each nerve is continuous with the spinal cord by ventral and dorsal roots. The latter bears a spinal ganglion- the DORSAL ROOT GANGLION. The cervical nerves enlarge from the first to the 6th nerve. The 7th and 8th cervical nerves and the 1st thoracic nerve are similar to the 6th cervical nerve in size. The remaining thoracic nerves are relatively small. Lumbar nerves are large, increasing in size from the 1st lumbar to the 5th. The 1st sacral nerve is the largest, thereafter the rest of the sacral nerves decrease in size. The coccygeal nerves are the smallest spinal nerves.

The paired dorsal and ventral nerve roots of the spinal nerves are continuous with the spinal cord. They cross the subarachnoid space and traverse the dura mater separately, uniting in or close to their intervertebral foramina to form the (mixed) spinal nerve. Ventral spinal roots contain efferent somatic and, in some levels, efferent sympathetic , nerve fibers which emerge from their spinal sources. There are also afferent fibers in these roots. The rootlets comprising each ventral root emerge from the anterolateral sulcus over an elongated vertical elliptical area. These rootlets come in series of 2 to 3 irregular rows in an area 3 mm in horizontal width. The ventral roots contain axons of neurones in the anterior and lateral spinal grey columns. The dorsal spinal roots bear ovoid swellings, the spinal ganglia, one on each root proximal to its junction with a corresponding ventral root in an intervertebral foramen. Each root fans out into 6 to 8 rootlets before entering the cord in a vertical row in the posterolateral sulcus. Dorsal roots are usually said to contain only afferent axons (both somatic and visceral) from unipolar neurones in spinal root ganglia, but they may also contain small (3%) of efferent fibers and autonomous vasodilator fibers. SPINAL GANGLIA (DORSAL ROOT GANGLIA): These are large groups of neurones on the dorsal spinal roots. Each is oval and reddish; its size is related to that of its root. A ganglion is bifid medially where the two fascicles of the dorsal root emerge to enter the cord. Ganglia are usually located in the intervertebral foramina, immediately lateral to the perforation of the dura mater by the roots. However, the first and second cervical ganglia lie on the vertebral arches of the atlas and axis; the sacral ganglion lies within the sacral vertebral canal and the coccygeal ganglion lies within the dura mater. The first cervical ganglia may be absent. Small aberrant ganglia sometimes occur on the upper cervical dorsal roots between the spinal ganglia and the cord.

The external surface of the spinal cord is marked by the presence of fissures and sulci. An anterior median fissure and a posterior median sulcus and septum almost completely separate the cord into right and left halves, but they are joined by a commissural band of nervous tissue which contains the central canal. The anterior median fissure extends along the whole ventral surface with an average depth of 3 mm, although it is deeper at caudal levels. It contains a reticulum of pia mater. Dorsal to it is the anterior white commissure. Perforating branches of spinal vessels pass from the fissure to the commissure to supply the central spinal canal. The posterior median sulcus is shallower, and from it a posterior median septum of neuroglia penetrates more than halfway into the cord, almost to the central canal. The septum varies in anteroposterior extent from 4 to 6 mm, and diminishes caudally as the canal becomes more dorsally placed and the cord contracts. A posterolateral sulcus exists from 1.5 to 2.5 mm lateral to each side of the posterior median sulcus. Dorsal roots(strictly rootlets) Of spinal nerves enter the cord along the sulcus. The white substance between the posterior median and posterolateral sulcus on each side is the POSTERIOR FUNICULUS. In the cervical and upper thoracic segments a longitudinal postero-immediate sulcus marks a septum dividing each posterior funiculus into large tracts: the FASCICULUS GRACILIS (medial) and the FASCICULUS CUNEATUS (lateral). Between the posterolateral sulcus and the anterior median fissure is the ANTEROLATERAL FUNICULUS. This is subdivided into ANTERIOR and LATERAL FUNICULI by ventral roots which pass through its substance to issue from the surface of the cord. The ANTERIOR FUNICULUS is medial to , and includes, the emerging ventral roots, while the LATERAL FUNICULUS lies between the roots and the posterolateral sulcus. In the upper cervical cord, nerve rootlets emerge through each lateral funiculus to form the SPINAL ACCESSORY which ascends in the vertebral canal lateral to spinal cord and enters the posterior cranial fossa via the foramen magnum.

Between the posterolateral sulcus and the anterior median fissure is the anterolateral funiculus which is subdivided into ANTERIOR and LATERAL FUNICULUS by ventral nerve roots. The ANTERIOR FUNICULUS is medial to, and includes, the emerging ventral roots. The LATERAL FUNICULUS lies between the ventral nerve roots and the posterolateral sulcus. In upper cervical segments, nerve rootlets emerge through the lateral funiculus to form the SPINAL ACCESSORY NERVE which ascends in the vertebral canal lateral to the spinal cord and enters the posterior canial fossa via the foramen magnum.

The spinal nerve roots exhibit different morphology in the different regions of the spinal cord. In the cervical region, the first upper cervical nerve roots are small; the distal 4 cervical roots the spinal roots are large. The thickness ratio of cervical dorsal roots to the ventral roots is 3:1. However, the 1st cervical root is an exception. The dorsal cervical root is smaller that the ventral root and, occasionally, is absent.

In the thoracic region, the thoracic roots are small in diameter with the exception of the 1st thoracic roots which still has the diameter same as the distal cervical segments. The dorsal roots only slightly exceed the ventral roots in thickness. As the distal thoracic segments are approached, the thoracic roots successively increase in length. In the lower thoracic region, the roots descend in contact with the spinal cord for at least two vertebrae before emerging from the vertebral canal.

The lower lumbar and upper sacral nerve roots have the largest diameter. The rootlets that composed the roots are most numerous. The coccygeal roots display the smallest diameter. The lumbar, sacral and coccygeal roots descend with increasing obliquity to their exits. The CAUDA EQUINA (Latin word meaning “horse tail”), are collection of spinal roots of the lower lumbar, sacral and coccygeal roots as these descend to their respective exits in increasing and obliquity.

Immediately distal to the spinal ganglia, ventral and dorsal roots unite to form spinal nerves. These very soon divide into DORSAL AND VENTRAL RAMI, both of which receive fibers from both spinal roots. At all levels above the sacral, this division occurs within the vertebral foramen. Division of the sacral spinal nerves occurs within the sacral vertebral canal, and the dorsal and ventral rami exit separately through posterior and anterior sacral foramina at each level. The dorsal, epaxial, ramus passes back lateral to the articular processes and divides into medial and lateral branches which penetrate the deeper muscles of the back: both branches innervate the adjacent muscles, and supply a band of skin from the posterior median line to the scapular line. The ventral, hypaxial, ramus is connected to a corresponding sympathetic ganglion by white and gray rami communicantes. It innervates the prevertebral muscles and curves round in the body wall to supply the lateral muscles of the trunk. Near the midaxillary line it gives off a lateral branch which pierces the muscles and divides into anterior and posterior cutaneous branches. The main nerve advances in the body wall, where it supplies the ventral muscles and terminates in branches to the skin.

At or distal to each origin each ventral ramus gives off the RECURRENT MENINGEAL (or, SINUVERTEBRAL) branches. These recurrent meningeal branches, numbering 2-4 filaments or branches on each side, occur at all vertebral levels. Each receives one or more rami from a nearby grey ramus communicans or directly from a thoracic sympathetic ganglion, and most pursue a recurrent (often perivascular) course into the vertebral canal through the intervertebral foramen ventral to the dorsal root ganglion. Here these mixed sensory and sympathetic nerves divide into transverse, ascending and descending branches which are distributed to the dura mater, the walls of the blood vessels, the periosteum, ligaments and intervertebral discs in the anterolateral region of the vertebral canal. Fine meningeal branches occasionally pass dorsal to reach the spinal ganglia to innervate the dorsal dura, periosteum, and ligaments, and others pass ventrally to innervate the posterior longitudinal ligaments. Ascending branches of the upper cervical meningeal nerves are large and distributed to the dura mater in the posterior cranial fossa. Meningeal nerves are important in relation to the referred pain which is characteristic of many spinal disorders and occipital headache.

Tubular prolongations of the spinal dura mater, closely lined by the arachnoid, extend around the spinal roots and nerves as they pass through the lateral zone of the vertebral canal and through the intervertebral foramina. These prolongations called the SPINAL NERVE SHEATHS (“root sheaths”), gradually lengthen as the spinal roots become increasingly oblique. Each dorsal and ventral root runs in the subarachnoid space with its own covering of pia mater. Each root penetrates the dura mater separately, taking with it a sleeve of ARACHNOID MATER before joining within the dural prolongation just distal to the distal ganglion. The dural sheaths of the spinal nerves fuse with the epineurium, within or lightly beyond the intervertebral foramina. The ARACHNOID prolongations within the sheaths do not extend as far distally as their dural coverings but the subarachnoid space and its contained CSF extend sufficiently distally to form a radiologically demonstrable ‘ROOT SLEEVE’ for each nerve. Shortening or obstruction of this sleeve seen on the myelogram indicates compression of the spinal nerve.

The ventral rami (anterior primary) supply the limbs and the anterolateral aspects of the trunk, and in general are larger than the dorsal rami. Thoracic ventral rami run independently and retain a largely segmental distribution. Cervical, lumbar and sacral ventral rami connect near the origins to form plexuses. Dorsi rami do not join these plexuses. Dorsal(posterior primary) rami of spinal nerves are usually smaller than the ventral rami and are directed posteriorly. Retaining a segmental distribution, all, except for the first cervical, 4th and 5th sacral and the coccygeal, divide into medial and lateral branches which supply the muscles and skin of the posterior regions of the neck and trunk.

Each cervical spinal dorsal ramus, except the first, divides into medial and lateral branches which all innervate the muscles. In general, only medial branches of the 2nd to 4th, and usually the 5th, supply the skin. Except for the 1st and 2nd, each dorsal ramus passes back medial to a posterior intertransverse muscle, curving round the articular process into the interval between semispinalis capitis and cervicis.

The first cervical dorsal ramus, the SUBOCCIPITAL NERVE, is larger than the ventral ramus. It emerges superior to the posterior arch of the atlas and inferior to the vertebral artery and enters the SUBOCCIPITAL TRIANGLE to supply the rectus capitis major and minor, obliquus capitis superior and inferior, and semispinalis capitis. A filament from the branch to the inferior oblique joins the second cervical dorsal ramus. The SUBOCCIPITAL NERVE occasionally has a cutaneous branch which accompanies the occipital artery to the scalp, and connects with the greater and lesser occipital nerves. It may also communicates with the spinal accessory nerve.

The SUBOCCIPITAL REGION is the area found at the superior part of the neck. It involves a triangular area known as the SUBOCCIPITAL TRIANGLE inferior to the occipital region of the head including the posterior aspects of C1 and C2 vertebrae. The SUBOCCIPITAL TRIANGLE lies deep to the trapezius and semispinalis capitis muscle. The boundaries and contents of the SUBOCCIPITAL TRIANGLE are: a. Superomedially, rectus capitis posterior major b. Superolaterally, superior oblique c. Inferolaterally, inferior oblique d. Floor, posterior atlanto-occipital membrane and posterior arch of C1 e. Roof, semispinalis capitis CONTENTS OF THE SUBOCCIPITAL TRIANGLE: VERTEBRAL ARTERY AND SUBOCCIPITAL NERVE(C1) There are 4 small muscles in this region, namely: Rectus capitis posterior major, rectus capitis posterior minor, inferior oblique of head, superior oblique of head. A. Rectus capitis posterior major arises from the spinous process of C2 vertebra and inserts into the lateral part of the inferior nuchal line of the occipital bone. B. Rectus capitis posterior minor arises from the posterior tubercle on the posterior arch of the C1 vertebra and inserts into the medial third of the inferior nuchal line. C. Inferior oblique of head arises from the spinous process of the C2 vertebra and inserts into the transverse process of the C1 vertebra. The name of this muscle is somewhat misleading because it is the “capitis” muscle that has no attachment to the cranium. D. Superior oblique of head arises from the transverse process of C1 and inserts into the occipital bone between the superior and inferior nuchal lines. The actions of the SUBOCCIPITAL GROUP of muscles is to extend the head on C1 and rotate the head and the C1 on C2 vertebrae.

The 2nd cervical dorsal ramus is slightly larger than its ventral pair. It is even larger than all the other cervical dorsal rami. It emerges between the posterior arch of the atlas and the lamina of the axis below inferior oblique, which it supplies. It receives connection from the first cervical dorsal ramus and divides into a large medial and smaller lateral branches. The medial branch, termed “GREATER OCCIPITAL NERVE” ascends between the inferior oblique muscle and the semispinalis capitis, pierces the latter and trapezius near their occipital attachments, and joined by a filament from the medial branch of the 3rd dorsal ramus. It ascends with the occipital artery, divides into branches which connect with the lesser occipital nerve, and supplies the skin of the scalp as far as forward as the vertex. It supplies the semispinalis capitis and, occasionally, the back of the ear. The lateral branch supplies the following: -splenius capitis -longissimus capitis -semispinalis capitis It is often joined by the corresponding third cervical branch. CLINICAL CORRELATION: GREATER OCCIPITAL NEURALGIA: refers to a syndrome of pain and paresthesia felt in the distribution of the greater occipital nerve. It is usually due to an entrapment neuropathy of the nerve as it pierces the attachment of the neck extensor to the occiput. A similar syndrome may be caused by upper facet joint arthritis involving the 2nd cervical root. The third cervical dorsal ramus is intermediate in size between the 2nd and the 4th. It comes around the articular pillar of the 3rd cervical vertebra, medial to the posterior intertransverse muscle, and divides into medial and lateral branches. Its medial branch runs between spinalis capitis and semispinalis cervicis, and pierces the splenius and the trapezius to end in the skin. Deep to the trapezius it gives rise to a branch, the THIRD OCCIPITAL NERVE, which pierces to end in the skin of the lower occipital region, medial to the greater occipital nerve and connected to it. The lateral branch often joins a branch of the 2nd cervical dorsal ramus. The dorsal ramus of the suboccipital nerve and the medial branches of the dorsal rami of the 2nd and 3rd cervical nerves are sometimes joined by loops to form the POSTERIOR CERVICAL PLEXUS

The third cervical dorsal ramus is intermediate in size between the 2nd an 4th . It courses back round the articular pillar of the 3rd cervical vertebra, medial to the posterior intertransverse muscle, and divides into medial and lateral branches. Its medial branch runs between spinalis capitis and semispinalis cervicis, and pierces the splenius and trapezius to end in the skin. Deep to the trapezius, it gives rise to a branch, the THIRD OCCIPITAL NERVE, which pierces trapezius to end in the skin of the lower occipital region, medial to the greater occipital nerve and connected to it. The lateral branch often joins a branch of the 2nd cervical dorsal ramus. The dorsal ramus of the SUBOCCIPITAL NERVE and the medial branches of the dorsal rami of the 2nd and 3rd cervical nerves are sometimes joined by loops to form the posterior cervical plexus.

The dorsal rami of the lower five cervical nerves (C4-C8) curve back round the vertebral articular pillars and divide into medial and lateral branches. Medial branches of the 4th and 5th run between the semispinalis cervicis and semispinalis capitis, reach the vertebral spines and pierce the splenius and trapezius to end in the skin. The medial branch of the 5th cervical ramus may not reach the skin. The medial branches of the lowest 3 cervical nerves are small and end in the semispinalis cervicis, semispinalis capitis, multifidus, and interspinales. The lateral branches supply the iliocostalis cervicis, longissimus cervicis and longissimus capitis.

Thoracic dorsal rami pass backwards close to the vertebral facet joints to divide into medial and lateral branches. Each medial branch emerges between a joint and the medial edges of the costotransverse ligament and intertransverse muscle. Each lateral branch runs in the interval between the ligament and the muscle before inclining posteriorly on the medial side of the levator costae. Medial branches of the upper six thoracic dorsal rami pass between and supply the semispinalis thoracis and multifidus, then pierce the rhomboids and trapezius, and reach the skin near the vertebral spines. Medial branches of the lower six thoracic dorsal rami mainly supply multifidus and longissimus thoracis and occasionally the skin the median region. Lateral branches increase inferiorly in size, and run through, or deep to, longissimus thoracis to the interval between it and iliocostalis cervicis, supplying these muscles and the levatores costarum. The lower five or six also have cutaneous branches, and pierce serratus posterior inferior and latissimus dorsi in line with the costal angles. Some upper thoracic lateral branches supply the skin. The 12th thoracic lateral branch sends a filament medially along the iliac crest, then passes down to the anterior gluteal skin. Medial cutaneous branches of the thoracic dorsal rami descend close to the vertebral spines before reaching the skin; the lateral branches descend across as many as four ribs before becoming superficial. The branch of the 12th thoracic reaches the skin a little above the iliac crest.

Lumbar dorsal rami pass back medial to the medial intertransverse muscles, and divide into medial and lateral branches. Medial branches run near the vertebral articular processes to end in the multifidus. They are related to the bone between the accessory and mamillary processes and groove it, crossing a distinct notch or even a foramen. Lateral branches supply the erector spinae. In addition, the upper three rami give rise to cutaneous nerves which pierce the aponeurosis of latissimus dorsi at the lateral border of the erector spinae and cross the iliac crest posteriorly to reach the gluteal skin, some reaching as far as the level of the greater trochanter. Sacral dorsi rami are small, diminishing downwards, and other than the fifth, all emerge through the dorsal sacral foramina. The upper three are covered at their exit by multifidus, and divide into medial and lateral branches. Medial branches are small and end in multifidus. Lateral branches join together and with lateral branches of the last lumbar and 4th sacral dorsal rami to form loops dorsal to the sacrum. Branches from these loops run dorsal to the sacrotuberous ligament and form a second series of loops under gluteus maximum. From these, 2 or 3 gluteal branches pierce the gluteus maximus (along a line from the posterior iliac spine to the coccygeal apex) to supply the posterior gluteal skin. The dorsal rami of the 4th and 5th sacral nerves are small and lie below multifidus. They unite with each other and with the coccygeal dorsal ramus to form loops dorsal to the sacrum: filaments from these supply the skin over the coccyx. COCCYGEAL DORSAL SPINAL RAMUS: does not divide into medical and lateral branches.

The vertebrae are supplied by periosteal and equatorial branches of the major cervical and segmental arteries and their spinal branches as mentioned above. The spinal branches enter the intervertebral foramina and divide into ANTERIOR AND POSTERIOR VERTEBRAL CANAL branches that pass to the vertebral body and vertebral arches, respectively. The larger branches of the spinal branches continue as terminal radicular or segmental medullary arteries distributed to the posterior and anterior roots of the spinal nerves and their coverings and to the spinal cord. `

Spinal veins form venous plexuses along the vertebral column both inside (Internal vertebral venous plexus) and outside(external vertebral venous plexus) the vertebral canal. The large tortuous BASIVERTEBRAL VEINS form within the vertebral bodies and emerge from the foramina on the surfaces of the vertebral bodies(mostly the posterior aspect) and drain into the external and especially the INTERNAL VERTEBRAL VENOUS PLEXUSES. The INTERVERTEBRAL VEINS receive veins from the spinal cord and vertebral venous plexuses as they accompany the spinal nerves through the INTERVERTEBRAL FORAMINA to drain into the vertebral veins of the neck and segmental veins of the trunk.

Spinal veins form venous plexuses along the vertebral column both inside( internal vertebral venous plexus) and outside(external vertebral venous plexus) the vertebral canal. The large, tortuous BASIVERTEBRAL VEINS form within the vertebral bodies and emerge from foramina on the surfaces of the vertebral bodies(mostly the posterior aspect) and drain into the external and especially the internal vertebral venous plexuses. The INTERVERTEBRAL VEINS receive veins from the spinal cord and vertebral venous plexuses as they accompany the spinal nerves through the intervertebral foramina to drain to the vertebral veins of the neck and segmental veins of the trunk.

The posterior and the anterior roots of the spinal nerves and their coverings are supplied by POSTERIOR and ANTERIOR RADICULAR ATERIES, which run along the nerve roots. These vessels do not reach the posterior or anterior spinal arteries. Segmental medullary arteries occur irregularly in the place of radicular arteries; they are larger vessels that make it to the spinal arteries.

The facet joints are innervated by the articular branches of the medial branches of the posterior rami> The vertebral column is innervated by the recurrent meningeal branches of the spinal nerves. Most of the meningeal branches run back to the intervertebral foramina but some remain outside of the vertebral canal. The branches outside of the canal supply the annulus fibrosus and anterior longitudinal ligament; those inside the canal supply the periosteum, ligamentum flavum, posterior aspect of the annulus fibrosus, posterior longitudinal ligament, spinal dura mater, and blood vessels within the vertebral canal.

The origins of the word KINESIOLOGY are from the Greek kinesis, to move and ology, to study. The study of kinesiology is dependent on 3 bodies of knowledge: ANATOMY, BIOMECHANICS, and PHYSIOLOGY. ANATOMY is the science of the shape and structure. BIOMECHANICS is a discipline that uses the principles of physics to quantitatively study how forces interact within a living body. PHYSIOLOGY is the biologic study of living organisms. KINESIOLOGY is a branch of mechanics that describes the motion of a body, without regard to the forces or torques that may produce the motion. In biomechanics the term body is used rather loosely to describe the entire body, or any of its parts or segments. Such as individual bones or regions. In general, there are 2 types of motions: TRANSLATION and ROTATION. TRANSLATION describes a linear motion in which all parts of a rigid body move parallel to and in the same direction as every other part of the body. Translation can occur in either straight line(RECTILINEAR) or a curved line (CURVILINEAR). ROTATION, in contrast, describes a motion in which an assumed rigid body moves in a circular path about some pivot point. As a result, all points in the body simultaneously rotate in the same angular process (e.g., clockwise and counterclockwise) across the same number of degrees. The pivot point for the angular motion is called the axis of rotation. The axis is at the point where motion of the rotating body is zero. For most of the movements of the body, the axis of rotation is located within or very near the structure of the joint. Movement of the human body, as a whole, is often described as a translation of the body’s center of mass, located generally just anterior to the sacrum. Although a person’s center of mass translate through space, it is powered by muscles that rotate the limbs.

OSTEOKINEMATICS describes the motion of bones relative to the three cardinal planes of the body with reference to the anatomic position. The SAGITTAL PLANE runs parallel to the sagittal suture of the skull dividing the body into right and left sections. The FRONTAL PLANE runs parallel to the coronal suture of the skull, dividing the body in FRONT and BACK. The HORIZONTAL( or TRANSVERSE PLANE) courses parallel to the horizon and divides the body into upper and lower section.

DEGREES OF FREEDOM refers to the number of independent movements allowed at a joint. Again the reference planes are the three cardinal planes of the body based on the anatomic position. In SAGITTAL PLANE, the movements allowed can be flexion and extension, dorsiflexion and plantarflexion, forward and backward bending. In FRONTAL PLANE, the movements allowed can be abduction and adduction, lateral flexion, ulnar and radial deviation, eversion and inversion. In the HORIZONTAL PLANE, the movements allowed are external and internal rotation, axial rotation.

In general, the articulations of two body segments constitute a joint. Movement at a joint can therefore be considered from 2 perspective: 1. the proximal segment rotating a fixed distal segment, or, 2. the distal segment rotating against a fixed proximal segment. The term knee flexion describes only the relative motion between the thigh and leg. It does not describe which of the two segments is actually rotating. To be exact, it does not describe the segment that is rotating and the segment that acts as the fixed segment. Terms such as tibial-on –femoral movement or femoral-on tibial movement adequately describe the OSTEOKINETICS.

Regional kinematics of the spine refers to the range and predominant direction of movements at the various regions of the vertebral column. The ZERO or the REFERENCE POINT used to describe the motion is the resting posture of the region while standing. The illustration above shows the normal sagittal plane curvatures across the regions of the vertebral column. The curvatures represent the normal resting posture of the region. At the cervical region, the normal cervical lordosis is 30-35 degrees; the thoracic kyphosis is 40 degrees, the lumbar lordosis 45 degrees.

The CRANIOCERVICAL REGION, or, the NECK, includes the structures involved in the articulation of the cranium to the cervical spine and the structures involved in the articulation of the C7 to T1.

The terms “craniocervical region” and “neck” are used interchangeably. Both terms refer to the combined set of 3 articulations: 1. ATLANTO-OCCIPITAL JOINT, 2. ATLANTO-AXIAL JOINT COMPLEX, 3. INTRACERVICAL APOPHYSEAL JOINTS (C2-C3). The craniocervical region is the most mobile area within the entire vertebral column. Highly specialized joints facilitate the positioning of the head, involving vision, hearing, smell, and equilibrium. The individual joints within the craniocervical region interact in a highly coordinated manner.

The atlanto-occipital joints provide independent movement of the cranium relative to the atlas. The joints are formed by the protruding convex condyles of the occipital bone fitting into the reciprocally concave superior articular facets of the atlas. The congruent convex-concave relationship provides inherent stability to the articulation. The concave-convex configuration of the atlanto-occipital joints permits angular rotation in 2 degrees of freedom. The primary motions are FLEXION and EXTENSION. Lateral rotation is slight. Axial rotation is restricted and not considered as a degree of freedom. Intra-articular fat pads are commonly found between the joint capsule and the margins of the articular cartilage. Anteriorly, the capsule of each atlanto-occipital joint blends with the anterior atlanto-occipital membrane and the anterior longitudinal ligament. Posteriorly, the capsule is covered by a thin, broad posterior atlanto-occipital membrane. The vertebral artery pierces the posterior atlanto-occipital membrane to enter the foramen magnum. This artery supplies blood to the brain.

The atlanto-axial joint complex consists of two joint structures: a median joint and a pair of laterally positioned apophyseal joints. The median joint is formed by the dens of C2 projecting through a ring created by the transverse ligament and the anterior arch of the atlas. The joint complex has two synovial cavities. The smaller anterior cavity consists of a synovial membrane that surrounds the articulation between the anterior side of the dens and the posterior border of the anterior arch of the atlas. A small anterior facet on the anterior side of the dens marks this articulation. The much larger posterior cavity has a synovial membrane that separates the posterior side of the dens and the a cartilage-lined section of the transverse ligament of the atlas. Because the dens acts as a vertical axis, the atlanto-axial joint is often described as a PIVOT JOINT. The 2 apophyseal joints of the atlanto-axial joint are formed by the articulation of the inferior facets of the atlas and the superior facets of the axis. The surfaces of these apophyseal joints are nearly flat and oriented close to the horizontal plane, a design that maximizes the freedom of AXIAL ROTATION. The atlanto-axial joint complex allows 2 degrees of freedom. About 50% of the total horizontal plane (axial) rotation within the craniocervical region occurs at the atlanto-occipital joint complex. The second degree of freedom is flexion and extension. Lateral flexion is very limited and not considered a degree of freedom. Two important connective tissues stabilizing the craniocervical junction deserve attention. These are the ff: 1. TECTORIAL MEMBRANE, 2. ALAR LIGAMENTS. The tectorial membrane is a broad, firm sheet of connective tissue just posterior to the transverse ligament. As the continuation of the posterior longitudinal ligament, the tectorial membrane attaches to the basilar part of the occipital bone, just anterior to the rim of the foramen magnum. It strengthens the attachment between the cranium and the cervical column by limiting the extremes of flexion and extension. The ALAR LIGAMENTS are tough fibrous cords that pass obliquely upward and laterally from the apex of the dens to the medial sides of the occipital condyles. Clinically referred to as “check ligaments”, the alar ligaments limit axial rotation of the head and atlas relative to the axis. Evident by their position, the alar ligament also limit lateral flexion.

The facet surfaces within the apophyseal joints of C2-C7 are oriented like shingles on a 45-degree sloped roof, approximately halfway between the frontal and horizontal planes. This orientation provides great freedom of movement in all three planes, a characteristic, or hallmark, of the cervical articulation.

Above illustration shows the kinematics of craniocervical flexion as it occurs at the atlanto-occipital joint, the atlanto-axial joint complex, and along the intracervical region from C2-C7. Note that flexion slackens the anterior longitudinal ligament and increases the space between the adjacent laminae and spinous processes. On the other hand, the vertebral arch ligaments, the supraspinous, interspinous ligaments, ligamentum flava, are elongated and taut.

Although highly variable, about 130 to 135 degrees of flexion and extension occur at the craniocervical region. The neutral resting posture of the craniocervical region is about 30 to 35 degrees. From the extended position , the craniocervical region extends an additional 85 degrees and flexes 45 to 50 degrees. In general, flexion and extension sequentially from cranial to caudal direction. About 20 to 25% of the total sagittal plane motion at the craniocervical region occurs over the atlanto-occipital joint complex, and the remainder over the appophyseal joints of C2- C7. The axis of rotation for flexion and rotation extends approximately in medial-lateral direction through each of the 3 joint regions: the occipital condyles at the atlanto-occipital joint, the dens at the atlanto-axial joint complex, and the bodies of C2-C7. The extremes of flexion and extension are limited primarily by tension in tissues located either posteriorly or anteriorly to the various axes of rotation. Flexion is also limited by the compresssion forces from the anterior margin of the annulus fibrosus, whereas extension is limited by the compression forces from the posterior margin of annulus fibrosus.

Like the rockers on a rocking chair, the convex occipital condyles roll forward in flexion and backward in extension within the concave superior articular facets of the atlas. Based on traditional convex-on-concave arthrokinematics, the condyles simultaneously slide slightly in the direction opposite to the roll. Tension on the tectorial membrane, articular capsules, and atlanto-occipital membranes limits the extent of the roll of the condyles. B. ATLANTO-AXIAL JOINT COMPLEX Although the primary motion at the atlanto-axial joint complex is axial rotation, the joint structure does allow about 15 degrees of flexion and extension. As a spacer between the cranium and axis, the ring-shaped atlas pivots forward during flexion and backward during extension. The extent of the pivot motion is limited in part by the dens that contacts the median joint of the atlanto-axial articulation. C. INTRACERVICAL ARTICULATION (C2-C7) Flexion and extension throughout the C2-C7 occur about an arc of motion that follows the oblique plane set by the articular facets of the apophyseal joints. During extension, which is initiated at the lower cervical spine(C4-C7), the inferior articular facets of superior vertebrae slide inferiorly and posteriorly, relative to the superior articular facets of the inferior vertebrae. These movement produce approximately 70 degrees of extension. Full extension is considered the close-packed position at the cervical apophyseal joints, as well as the other regions throughout the vertebral column. This position results in maximal joint contact and load-bearing. The inferior sliding of the articular facets of superior vertebrae tends to slacken the joint capsule. The close-packed position of most synovial joints increases the tension in the surrounding capsule and associated ligaments. The apophyseal joints are one of the few exception to this general rule. Flexion is also initiated at the lower cervical spine (C4-C7). The movements are the reverse of extension. The inferior facets of the superior vertebrae slide superiorly and anteriorly, relative to the superior facets of the inferior vertebrae. The sliding movements between the articular facets produces approximately 35 degrees of flexion. Flexion stretches the capsule of the apophyseal joints and reduces the area for joint contact. Overall, approximately 105 degrees of cervical flexion and extension occur as a result of the sliding between the apophyseal joint surfaces. This extensive range of motion is due in part to the relatively long and unobstructed arc of motion provided by the oblique plane of the facet surfaces. On average, about 20 degrees of sagittal plane motion occur at each intervertebral junction between C2-C3 and C6-C7. This is considerably greater angular motion than at the thoracic region. The largest angular displacement tends to occur between C5-C6, possibly accounting for the relatively high incidence of spondylosis, and hyperflexion-related fractures at this level.

In addition to flexion and extension in the craniocervical region, the head can also translate forward(PROTRACTION) and backward(RETRACTION) within the sagittal plane. PROTRACTION of the head flexes the lower-to-mid cervical spine and extends the upper craniocervical region. RETRACTION of the head, in contrast, extends or straigthens the lower-to-mid cervical spine and flexes the upper craniocervical region. In both movements, the lower-to-mid cervical spine follows the translation of the head. Although protraction and retraction of the head are physiologically normal useful motions, they may be associated with faulty posture. Prolonged periods of protraction may lead to a chronic forward head posture, causing increased strain on the craniocervical extensor muscles.

The bar graph above is an in vitro cervical flexion and extension motion study involving over 10 cadaveric specimen. The bar is expressed as a percent of the total range of sagittal plane motion in the cervical spine. It is lowest at the C2-C3 junction gradually increasing with the greatest motion at C5-C6 intervertebral junction.

The atlanto-axial joint complex is designed for maximal rotation within the horizontal plane. The design is most evident by the structure of the axis (C2), with its vertical dens and nearly horizontal superior articular facets. The ring-shaped atlas “twists” about the dens, producing about 40 to 45 degrees of axial rotation in each direction. The flat to slightly concave inferior articular facets of the atlas slide in a circular path across the broad “shoulders” of the superior facets of the axis. These surfaces have also been described as lightly convex when considering the thickness of the articular cartilage. Because of the limited axial rotation permitted at the atlanto-occipital joint, the cranium follows the rotation of the atlas, essentially degree for degree. The axis of rotation of the head and atlas is through the vertical projected dens. Horizontal plane rotation of the atlas is coupled with slight lateral flexion to the opposite side. Tension in the alar ligaments increases with rotation at the atlanto-axial joint complex especially in the ligament located opposite to the direction of the rotation. Tension of the alar ligaments and capsules of the lateral apophyseal joints, plus the many muscles about the neck limit axial rotation.

Axial rotation of the head and neck is a very important function, intimately related to vision and hearing. As shown above, the craniocervical region rotates about 90 degrees to each side, for a total range of nearly 180 degrees. With an additional 150 to 160 degrees of total horizontal plane movement of the eyes, the visual field approaches 360 degrees, with little or no movement of the trunk. Other factors, of course, influence this wide visual fields. These are the range of motion and sight. About 50% of axial rotation of the craniocervical region occurs at the atlanto-axial joint complex, with the remaining throughout C2-C7. Rotation of the atlanto-occipital joint is restricted due to the deep-seated placement of the occipital condyles within the articular facets of the atlas.

Rotation throughout C2-C7 is guided primarily by the spatial orientation of the facet surface within the apophyseal joints. The facet surfaces are oriented 45 degrees between the horizontal and frontal planes. The inferior facets slide posteriorly and somewhat inferiorly on the same side of the rotation, and anteriorly and somewhat superiorly on the side opposite the rotation. Approximately 45 degrees of axial rotation occur to each side over the C2-c7 region, nearly equal to that permitted at the atlanto-axial joint complex. Rotation is greatest in the more cranial vertebral segments.

Approximately 40 degrees of lateral flexion is available to each side throughout the craniocervical region. The extremes of movement can be demonstrated by attempting to touch the ear to the tip of the shoulder. Most of this movement occurs at the C2-C7 region; however about 5 degrees may occur at the atlanto-occipital joint. Lateral flexion at the atlanto-axial joint complex is negligible.

The inferior articular facets on the side of lateral flexion slide inferiorly and slightly posteriorly, and the inferior articular facets on the side opposite the lateral flexion slide superiorly and slightly anteriorly. The approximate 45 degree inclination of the articular facets of C2-C7 dictates the mechanical coupling between movements in the frontal and horizontal plane. Because an upper vertebra follows the plane of the articular facet of the lower vertebra, component of lateral flexion and axial rotation must occur simultaneously. For this reason, lateral flexion and axial rotation in the mid-to-low cervical region are mechanically coupled in an ipsilateral fashion; for example, lateral flexion to the right occurs with slight axial rotation to the right, and vice versa.

The thoracic region of the vertebral column has peculiar characteristics that make it distinct from the cervical and the lumbar regions. It is the longest part of the vertebral column that is relatively rigid and is interposed between 2 mobile spinal regions. Its relative rigidity is due to the presence of the rib cage which is formed by the ribs, sternum and the thoracic vertebrae. This relative rigidity of the thoracic region provides 3 functions: 1. a stable base for muscles to control the craniocervical region and the upper extremities, 2. protection of the intrathoracic region, 3. mechanical bellows for breathing. The thoracic vertebrae are well stabilized by the ribs and associated costovertebral and costotransverse joints. Stability protects the spinal cord from trauma. During a fall, for example, the impact to the thoracic spine is partially absorbed and dissipated by the ribs and the associated muscles and connective tissues.

The thoracic spine has 24 apophyseal joints, 12 on each side and these provide the primary mechanism for thoracic mobility. However, their potential for mobility is restricted by the adjacent COSTOVERTEBRAL AND COSTOTRANSVERSE joints which tie mechanicaly most of the thoracic region anteriorly to the sternum.

Most COSTOVERTEBRAL joints connect the head of a rib with a pair of costal facets and the adjacent margin of an intervening intervertebral disc. The articular surfaces of the costovertebral joints are highly ovoid held together primarily by capsular and radiate ligaments. COSTOTRANSVERSE joints connect the articular tubercle of a typical rib to the costal facet on the transverse process of a corresponding thoracic vertebra. The extensive (nearly 2 cm long) costotransverse ligament firmly anchors the neck of the rib to the entire length of a corresponding transverse process. In addition, each costotransverse ligament is stabilized by a superior costotransverse ligament. This strong ligament attaches between the superior margin of the neck of one rib and the inferior margin of the transverse process of the vertebra located above. Ribs 11 and 12 usually lack costotransverse joints.

Range of motion at each thoracic intervertebral junction is small. However, cumulative motion over the entire thoracic spine is considerable. Approximately 30 to 40 degrees of flexion occurs throughout the thoracic vertebral region alone. However, in situation like shown above where there is involvement of the thoracolumbar regions, the range of flexion goes higher to 85 degrees- a sum of 35 degrees of thoracic flexion and 50 degrees of lumbar flexion The movement of the articular surfaces at the apophyseal joints are essentially similar to that of the C2-C7 apophyseal joints. If there are subtle differences, these are attributed primarily to the different shapes of the vertebrae and the spatial orientation of the facets. For example, flexion between T5-T6 occurs by superior and slightly anterior sliding of the inferior facet surfaces of T5 on the superior facet surfaces of T6. Extension occurs by a reverse process- that is inferior and slightly posterior sliding of the inferior facet surfaces of T5 on the superior facet surfaces of T6.

Approximately 20-25 degrees of extension is available over the entire thoracic region. However, in thoracolumbar coupling as shown above, 35-40 degrees of flexion is available. Note that the amount of extension contributed by the lumbar region is less compared to the thoracic region as far as thoracolumbar coupling is concerned. Unlike in thoracolumbar flexion, the amount of flexion contributed by the lumbar region is much greater than the thoracic region by as much as 15 degrees. The extremes of extension in the thoracic region are limited by the potential impingement between adjacent downward-sloping spinous process especially at the midthoracic vertebrae. In general the magnitude of flexion and extension increases in a cranial-to-caudal.

Approximately 30 degrees of horizontal plane(axial) rotation occurs to each side throughout the thoracic region. In general, the degree of axial rotation decreases in the thoracic region in a cranial-to-caudal direction. In the mid to lower thoracic spine, the greater vertically oriented apophyseal joints tend to block horizontal plane motion. In the thoracolumbar region however, axial rotation has 35 degree-arc- a sum of 30 degrees of thoracic region and 5 degrees of lumbar rotation.

The predominant frontal plane orientation of the thoracic facet surfaces suggests a relative freedom of lateral flexion. This potential for movement is never fully expressed, however, because of the stabilization provided by the attachment to the ribs. Lateral flexion in the thoracic region is, most of the time, coupled with lateral flexion of the thoracolumbar region as illustrated above. However, pure flexion of the thoracic region has approximately 25 degrees to each side. This magnitude of this intervertebral motion remains relatively constant throughout the entire thoracic region. Lateral flexion occurs as the inferior facet of the superior vertebra slides superiorly on the side contralateral to the lateral flexion and inferiorly on the side ipsilateral to the lateral flexion. Note that the ribs slightly drop on the side of the lateral flexion, and rise slightly on the side opposite the lateral flexion. As in the cervical spine, lateral flexion and axial rotation are mechanically coupled in an ipsilateral manner. Coupling is most evident in the upper thoracic spine where the articular facets possess a closer orientation to those in the lower cervical region. The influence of coupling decreases and is inconsistent in the middle and lower thoracic regions.

The facet surfaces of lumbar apophyseal joints are oriented nearly vertical, with moderate-to-strong sagittal plane bias. The orientation of the superior articular facet of L2, as shown by the above illustration, is 25 degrees. This orientation favors sagittal plane motion at the expense of axial rotation. This trend is evident even in the mid-to-lower thoracic regions.

The facet surfaces change their orientation rather abruptly at or near the thoracolumbar junction. The sharp frontal-to-sagittal plane transition may help to explain the relatively high incidence of traumatic paraplegia at this junction. The thorax, being held relatively rigid by the rib cage, is free to flex as a unit over the lumbar region. A large flexion torque delivered to the thorax may concentrate an excessive hyperflexion stress at the extreme upper lumbar region. If severe enough, the stress may fracture or dislocate the bony elements and possibly injure the caudal end of the spinal cord or the cauda equina. Surgical fixation devices implanted to immobilize an unstable thoracolumbar junction are particularly susceptible to stress failure compared with other regions of the vertebral column.

As any intervertebral junction, the L5-S1 junction has an interbody joint anteriorly and a pair of apophyseal joint posteriorly. The facet surfaces of the L5-S1 apophyseal those of other lumbar regions. The base(top) of the sacrum is naturally inclined anteriorly and inferiorly, forming an approximate 40-degree sacrohorizontal angle while standing. Given this angle, the resultant force due to body weight (BW) creates an anterior shear (BWs) and a compressive force (BWn) acting perpendicular to the superior surface of the sacrum. A typical sacrohorizontal angle of 40 degrees has a magnitude anterior shear force acting at L5-S1 junction equal to 64% of body weight. Increasing the sacrohorizontal angle also increases the anterior shear. For example, increasing the sacrohorizontal angle to 55 degrees increases the anterior shear force to about 82% of superimposed body weight. While standing or sitting, lumbar lordosis can be increased by anterior tilting of the pelvis. Tilting of the pelvis is defined as a short-arc sagittal plane rotation of the pelvis relative to the femurs. The direction of the tilt is indicated by the direction of rotation of the iliac crests of the pelvis. Several structures stabilize the anterior-posterior alignment of the L5-S1 junction, especially the anterior longitudinal ligament and the iliolumbar ligament.

The ANTERIOR LONGITUDINAL LIGAMENT crosses anterior to the L5-S1 junction. The ILIOLUMBAR LIGAMENT arises from the inferior aspect of the transverse process of L5 and adjacent fibers of the QUADRATUS LUMBORUM muscle. The ligament attaches inferiorly to the ilium, just anterior to the sacroiliac joint, and to the lateral aspect of the sacrum. As a bilateral pair, the iliolumbar ligaments provide a firm anchor between the lower lumbar vertebrae and the underlying ilium and sacrum. The wide, sturdy articular facets of the L5-S1 apophyseal joints provide bony stabilization to the L5-S1 junction. The near frontal plane inclination of the facet surfaces can resist part of the anterior shear at this region. This blockage creates a force within the apophyseal joint. Without adequate stabilization, the lower end of the lumbar region can slip forward relative to the sacrum. This abnormal, potentially serious condition is known as SPONDYLOLISTHESIS.

While standing the lumbar region in the healthy adult typically exhibits about 40-45 degrees of lordosis. Lumbar lordosis is greater in women than in men, with the greatest differences appearing after the 5th decade. Compared with standing, sitting reduces the lordosis by about 20 to 35 degrees. About 50 degrees of flexion and 15 degrees of extension occur at the healthy lumbar spine. This is a substantial range of motion considering it occurs across only 5 intervertebral junctions. This predominance of sagittal plane motion is largely due to the prevailing sagittal plane bias of the facet surfaces in the lumbar apophyseal joints. As a general principle, the amount of lumbar intervertebral flexion and extension gradually increases in a cranial-to-caudal directions. There is also a strong kinematic relationships between the lumbar region, the trunk as a whole and the lower extremities. Pelvic-on-femoral(hip) flexion increases the passive tension in the stretched hamstring muscles. With the lower end of the vertebral column fixed by te sacroiliac joints, continued flexion of the middle and upper lumbar region reverses the natural lordosis of the back. During flexion, between L2-L3 for example, the inferior facets of L2 slide superiorly and anteriorly, relative to the superior facets of L3. As a consequence, muscular and gravitational forces are transferred away from the apophyseal joints, which generally support about 20% of the total spinal load in erect standing, and toward the discs and posterior spinal segments. Discs are compressed while the posterior ligaments are tensed. In extreme flexion, the fully stretched articular capsule of the apophyseal joints restrains additional forward migration of the superior vertebra. The extreme flexed position significantly reduces the contact area within the facet surfaces of the apophyseal joints. Paradoxically, although a fully flexed lumbar reduces the total force on a given apophyseal joint, the pressure (force per unit area) increases on the decreased surface area under contact. High pressure may damage joints that have abnormally developed articular surfaces. The kinematics of flexion of the lumbar region, as shown by the above illustration, is taken in context with flexion of the trunk and hips. P

The bar graph shows the results from cadaveric experiments on the relative resistance provided by nonmuscular tissues against a flexion torque at the lumbar spines. There is relatively large resistance provided by the stretched articular capsule of the apophyseal joints. This is followed by the intervertebral discs. The ligamentum flavum offering the least resistance. Of clinical interest is the relatively large resistance provided by the stretched articular capsule that surrounds the flexed apophyseal joints. In the healthy lower back, the passive tension within the capsule of flexed apophyseal joints reduces the compression load on the intervertebral discs. A weakened or overstretched articular capsule, however, may not be able to generate sufficient tension to protect the discs from injury. This might be true in a chronic, slumped sitting posture where the capsules of the apophyseal joints are overstretched.

Extension of the lumbar spine is essentially the reverse of flexion. Extension between L2-L3, for example, occurs as the inferior articular facets of L2 slide inferiorly and slightly posteriorly relative to the superior facets of L3. Full extension increases both the amount of load and area of contact at the apophyseal joints. When lumbar extension is combined with full hip extension, passive tension in the stretched hip flexors helps maintain lordosis by anteriorly tilting the pelvis. In the neutral standing posture, the healthy disc is the primary load-bearing structure in the lumbar region. As such, healthy discs reduce the load imposed apophyseal joints and thereby protect them from excessive wear. In diseased or severely dehydrated disc, however, a greater portion of the total load is shifted to the apophyseal joints. It is not uncommon, therefore, for a person with severe disc disease to develop osteoarthritis in the lumbar apophyseal joints.

Flexion and extension of the lumbar spine can occur by two fundamentally different movement strategies. The first strategy is typically used to maximally displace the upper trunk and upper extremities relative to the thighs, such as when lifting or reaching. This strategy combines maximal flexion and extension of the lumbar spine with a wide arc of pelvic-on-femoral(hip) and trunk motion.

A second movement strategy involves a relatively short-arc tilt of the pelvis. As shown above, an anterior or a posterior pelvic tilt accentuates or reduces lumbar lordosis. The change in lordosis alters the position of the nucleus pulposus within the disc and alters the diameter of the intervertebral foramina. The axis of rotation for pelvic tilting is through both hip joints. This mechanical association strongly links the movement(pelvic-on-femoral) of the hip joints with that of the lumbar spine. THERAPEUTIC AND KINESIOLOGIC CORRELATIONS BETWEEN ANTERIOR PELVIC TILT AND INCREASED LUMBAR LORDOSIS: Active anterior tilt of the pelvis is caused by the hip flexor and back extensor muscles. Strengthening and increasing the control of these muscles, in theory, favors a more lordotic posture of the lumbar spine. Although this idea is intriguing, whether a person can subconsciouslly adopt and maintain a newly learned pelvic posture is uncertain. Nevertheless, maintaining the natural lordotic posture in the lumbar spine is a fundamental principle espoused by Mckenzie for persons with a herniated disc. Increased lumbar extension reduces the pressure within the disc and, in some cases, reduces the contact pressure between the displaced nuclear material and the neural elements. Evidence of the latter is often described as “CENTRALIZATION” of low back pain, meaning that discogenic pain(formerly in the lower extremities due to nerve root impingement) migrates toward the back. Centralization, therefore, suggests reduced disc pressure on the nerve root.

Extension of the lumbar spine and its effect on the diameter of the intervertebral foramen and migration of the annulus pulposus: Relative to the neutral position, full lumbar extension reduces the volume within the vertebral canal by 15%. For this reason, clinicians often suggest that a person with nerve root impingement, from a stenosed intervertebral foramen, limit acitivities that involved hyperextension. Extension, however, tends to migrate the annulus fibrosus anteriorly. Person with nuclear protrusion or prolapsed may find, therefore, that extension reduces pain associated with pressure on the spinal cord or nerve roots. The normal lumbar lordotic posture may restrict the migration of the nucleus pulposus within a weakened disc from approaching the neural elements. It is uncertain whether the nucleus pulposus migrates in a similar manner in both healthy and degenerated discs. LUMBAR FLEXION: ITS EFFECT ON THE DIAMETER OF THE INTERVERTEBRAL FORAMEN AND MIGRATION AND MIGRATION OF THE NUCLEUS PULPOSUS Relative to a neutral position, full flexion of the lumbar spine increases the diameter of the intervertebral foramina by 195 and increases the volume of the vertebral canal by 11%. Therapeutically, flexion of the lumbar region is often used to temporarily reduce the pressure on a lumbar nerve root that is impinged by an obstructed foramen. In certain circumstances, however, this potential therapeutic advantage can be associated with a potential therapeutic disadvantage. For example, flexion of the lumbar region generates compression forces on the anterior side of the disc, which tend to migrate the nucleus pulposus posteriorly. The magnitude of the migration is small in a healthy spine. In a person with a weakened posterior annulus, however, posterior migration of the nucleus pulposus increases pressure on the spinal cord or nerve roots. THERAPEUTIC AND KINESIOLOGIC CORRELATIONS BETWEEN POSTERIOR PELVIC TILT AND DECREASED LUMBAR LORDOSIS: Active posterior tilting of the pelvis is produced by hip extensors and abdominal muscles. Strengthening and increasing the patient’s conscious control over these muscles theoretically favors a reduced lumbar lordosis. This concept was the trademark of the “WILLIAMS FLEXION EXERCISES,” a therapeutic approach that stressed stretching the hip flexors and back extensor muscles and strengthening the abdominal and hip extenor muscles. In principle, these exercises are most appropriate for persons with back pain related to excessive lordosis and significantly increased lumbohorizontal angle. This posture, according to Williams, was associated with degenerative disc disease, stenosis of the lumbar intervertebral foramen, osteophyte formation with nerve root irritation, and anterior spondylolisthesis.

Relative to a neutral position, full flexion of the lumbar spine increases the diameter of the intervertebral foramina by 19% and increases the volume of the vertebral canal by 11%. Therapeutically, flexion of the lumbar region is often used to temporarily reduce the pressure on a lumbar nerve root that is impinged by an obstructed intervertebral foramen. In certain circumstances, this potential therapeutic advantage may be associated with a potential therapeutic disadvantage. For example, flexion of the lumbar region generates compression forces on the anterior side of the disc, which tend to migrate the nucleus pulposus posteriorly. The magnitude of the migration is small in the healthy spine. In a person with a weakened posterior annulus fibrosus, however, posterior migration of the nucleus pulposus increases pressure on the spinal cord or nerve roots. These contrasting therapeutic effects of flexion in the lumbar regionare to be considered when planning an exercise program for a person with generalized low back pain.

The lumbar region may demonstrate greatly exaggerated lordosis that is undesirable from a medical perspective. Such structure may be found in residuals of postpolio infection where there is severe hip flexion contracture and increased passive tension in the hip flexor muscles. The possible negative results of this exaggerated lumbar lordosis are increased compression force on the apophyseal joints and increased anterior shear at the lumbosacral junction leading to spondylolisthesis.

In conjunction with the hip joints, the lumbar region provides the major flexion and extension pivot point for the trunk, especially during activities such as forward bending, climbing and lifting. LUMBOPELVIC RHYTHM is the kinematic relationship between the lumbar spine and hip joints during sagittal plane movements. An understanding of the normal lumbopelvic rhythm during flexion and extension of the trunk can help distinguish pathology affecting the spine and that affecting the hips. Consider the common action of bending forward and toward the ground while keeping the knees straight. This motion is measured as combination of about 40 degrees of lumbar flexion and 70 degrees of hip (pelvic-on femoral) flexion. The hips and lumbar spine flex simultaneously throughout the arc of trunk flexion but this motion is initiated at the lumbar spine. Figures B and C show obvious abnormal lumbopelvic rhythms associated with marked restriction in mobility at the hip joints (B) or lumbar region . In both B and C, the amount of overall trunk flexion is reduced. If greater trunk flexion is required, the hip joints or lumbar region may mutually compensate for the other’s limited mobility. This situation may increase the stress on the compensating region. As depicted in fig. B, with limited hip flexion due to restricted hamstring extensibility, for example, bending the trunk toward the floor requires greater flexion in the lumbar and lower thoracic spine. Eventually, exaggerated flexion may overstretch posterior connective tissues, such as the interspinous ligaments, posterior annulus fibrosus, posterior longitudinal ligament, apophyseal joint capsules and thoracolumbar fascia, or increase stress on the discs and apophyseal joints. In contrast, as shown in fig. C, limited mobility in the lumbar spine may require greater flexion of the hip joints. Greater forces may be required from the hip extensor muscles which as a consequence, increase the compression force at the hips. In persons with healthy hips, this relatively low-level increase in compression force is usually tolerated without cartilage degeneration or discomfort. In a person with a preexisting hip condition like osteoarthritis, or, gross joint asymmetry, the increased compression force may accelerate degenerative changes.

The typical lumbopelvic rhythm used to extend the trunk from a forward bent position is shown in the above illustration. Extension of the trunk with knees extended is normally initiated by extension of the hips, then followed by extension of the lumbar spine. This normal lumbopelvic rhythm reduces the demands on the lumbar extensor muscles and underlying apophyseal joints and discs, thereby protecting the region against high stress. Delay in lumbar extension shifts the extensor torque demand to the powerful hip extensors(hamstrings and gluteus maximus), at the time when the external flexion torque on the lumbar region is greatest(external moment arm depicted as dark black line). In this scenario, the demand on the lumbar extensor muscles increases only after the trunk is sufficiently raised and the external moment arm, relative to the body weight, is minimal. Persons with severe low back pain may purposely delay contraction of the lumbar extensor muscles until the trunk is nearly vertical. After standing completely upright, hip and back muscles are typically inactive, as long as the vector due to the body weight falls posterior to the hip joints.

For many persons, a lot , a time is spent sitting, either at work, school, or home, or in a vehicle. The posture of the pelvis and lumbar spine has a large influence on the posture in other areas of the vertebral column particularly the lumbar and craniocercervical regions. In the illustration depicting two classical postures- the slouching or “poor” posture and the “ideal” sitting posture. In the poor slouched posture, the pelvis is posteriorly tilted with a lightly flexed (flattened) lumbar spine. Eventually, this posture may lead to adaptive shortening in tissues that maintain this posture. Tissues that, if shortened, predispose a person to slouched sitting posture with a posterior tilted pelvis: 1. Hamstring muscles 2. Anterior longitudinal ligament 3. Anterior fibers of the annulus fibrosus A habitually slouched sitting posture may, in time, overstretch and weaken the posterior annular fibrosus, reducing its ability to block a protruding nucleus pulposus. A slouched sitting posture typically increases the external moment arm between the line-of-force of the upper body weight and lumbar vertebrae. As a consequence, the greater flexor torque increases the compression force on the anterior margin of the lumbar discs. In vivo pressure measurements typically demonstrate larger pressures within the lumbar discs in slouched sitting position compared with the erect sitting.

The sitting posture of the pelvis and the lumbar spine strongly influences the posture of the entire skeletal axial skeleton including the craniocervical region. A flat posture of the low back is associated with a more protracted head (i.e., a “ forward head”) posture. Sitting with the lumbar spine flexed tips the thoracic and lower cervical regions forward into excessive flexion. In order to maintain a horizontal visual gaze- such as that typically required to view a computer monitor- the upper craniocervical region must compensate by extending slightly. Over time, this posture may result in adaptive shortening in the small posterior suboccipital muscles. A prolonged slouched sitting posture may be an occupational hazard. It may increase the muscular stress at the base of the cervical spine. The forward –head posture increases the external flexion torque on the cervical column as a whole, requiring greater force production from the extensor muscles and local connective tissues. Sitting posture may be improved by a combination of awareness, strengthening and stretching appropriate muscles; eyeglasses; and ergonomically designed seating, which includes adequate lumbar support

The ideal sitting posture with natural lordosis and increased anterior pelvic tilt extends the lumbar spine. The change in posture at the base (inferior aspect) of the spine has an optimizing influence on the posture

FLEXION: Bilateral action of : Rectus abdominis. Psoas major, Gravity EXTENSION: Erector spinae , Multifidus, semispinalis thoracis Rhomboids, Serratus Anterior ROTATION: Unilateral action of : Rotatores, Multifidus, Iliocostalis, Longissimus, External oblique acting synchronously with opposite oblique, Splenius thoracis.

One of the most common medical complaints that bring patients to clinic is BACK PAIN, and the most common cause of this is BACK STRAIN. Back strain results from extreme movements of the vertebral column such as extension or rotation. Such extreme movements result in stretching or microscopic tearing of muscle fibers and/or ligaments of the back. The muscles involved are usually those producing movements of the lumbar intervertebral joints, especially the ERECTOR SPINAE muscles. If the weight is not properly balanced on the vertebral column, strain is exerted on the muscles. As a protective mechanism, the back muscles go into SPASM after an injury or in response to inflammation of structures such as the ligaments. The anatomic significance of the SUBOCCIPITAL TRIANGLE is that it is where the vertebral arteries pass to supply parts of the brain. The vertebral arteries have winding course as these pass through the SUBOCCIPITAL TRIANGLE. Medical condtion like arteriosclerosis reduces blood flow in this anatomical part of the course of the vertebral arteries, and therefore, reduces the blood flow to the brainstem. This ischemic condition of the brainstem may manifest in situation of prolong turining of the head-as occurs when backing up a motor vehicle. Signs and symptoms may include lightheadedness, dizziness, or vertigo.

The stability of the CRANIOVERTEBRAL JOINTS is maintained by the ligaments. Consequently, excessive movements of the head during vehicular accidents, falls, and other violent events cause rupture of the stabilizing ligaments especially the TRANSVERSE LIGAMENTS and the ALAR LIGAMENTS. Rupture of the alar ligaments can occur with combined flexion and rotation of the head and can increase by 30% of the range of movement of the head to the opposite side. If the TRANSVERSE LIGAMENT is intact, no neurologic deficit in the form of incomplete paralysis or in the form of quadriplegia occurs. However, if the transverse ligament is ruptured, the dens is set free and resulting in ATLANTOAXIAL SUBLUXATION of the median ATLANTOAXIAL joint. If there is complete dislocation of the median atlantoaxial joint the DENS may be driven to the upper part of the cervical spinal cord causing QUADRIPLEGIA (complete paralysis of both the upper and lower extremities). If the DENS is driven more proximally to the MEDULLA of the brainstem, death occurs.

CLINICAL ANATOMY THE BACK DANILO V. OLEGARIO, MD, FPOA, FPCS SILLIMAN UNIVERSITY SCHOOL OF MEDICINE CITY

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION COURSE OBJECTIVES: BE ABLE TO KNOW THE FOLLOWING: 1.THE IMPORTANCE OF THIS PARTICULAR ANATOMIC REGION 2. THE DIFFERENT ANATOMICAL STRUCTURES FOUND IN THIS REGION 3. THE CORRELATION BETWEEN THE FORM AND THE FUNCTION OF THE DIFFERENT STRUCTURES OF THIS REGION 4. THE CLINICAL APPLICATION OF THE ANATOMIC KNOWLEDGE OF THIS REGION

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION COURSE DURATION: 6 SESSIONS ATTENDANCE: EXAMS: 1. LONG WEEKLY WRITTEN EXAM -format: case analysis 2. SHORT UNANNOUNCED WRITTEN EXAM -covers topic on previous lectures 3. ORAL EXAM - previous lectures - clinical topics 4. CLINICAL TOPICS FOR GROUP STUDY A. HERNIATED NUCLEUS PULPOSUS(HNP) 1. Anatomy of the Intervertebral Disc 2. Tissue Structure and Function 3. Types of HNP

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION CLINICAL TOPICS FOR GROUP STUDY: B. SPINAL PROCEDURES: 1. INTRADURAL/EXTRADURAL SPINAL ANESTHESIA A. Anatomic Relations Peculiar to the Lower Lumbar Spinal Canal B. Anatomy of the Spinal Meninges and their Spaces C. Surface Projections of the Lower Lumbar Spine

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION CLINICAL TOPICS FOR GROUP STUDY C. SPINAL INFECTION 1. POTT’S DISEASE a. Pathogenesis of Pott’s Disease b. Pathoanatomy of Pott’s Disease c. Clinical Manifestations D. SPINAL DEFORMITY 1. Scoliosis a. Definition of Scoliosis b. Types of Scoliosis c. Prognostic Factors Affecting Scoliosis

CLINICAL ANATOMY: THE BACK INTRODUCTION TO THE COURSE ORAL EXAM FORMAT: -RANDOM SELECTION: -all the students’ name will be written in a piece of paper and will be placed in a container. Someone will be asked to draw a couple of names who will take the oral exam. -Each examinee will be given 3 questions to answer - SAMPLE QUESTIONS: 1. If you see a penetrating wound located between the middle of the medial border of the left scapula and the vertebral column, give the layer of tissues penetrated from the skin to the level of the deep layer of intrinsic back muscles. 2. At this level of the back, what is the most superficial layer of extrinsic muscle that is dominant in this area? 3. If on xray of the spine, you see a bullet lodged between C7 and T1, what nerve root is affected at this level? -FREQUENCY OF DRAWS: The name of the examinee will not be drawn again until all students have taken the oral exam. Then the cycle will be repeated again.

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION REFERENCES: 1. ANDERSON,JAMES E., MD, GRANT’S ATLAS OF ANATOMY, 1OTH ED., THE WILLIAMS AND WILKINS COMPANY 2. SNELL, RICHARD S., CLINICAL ANATOMY, 7TH ED., LIPPINCOT WILLIAMS AND WILKINS, 1994. 3. MOORE, KEITH L., AGUR, ANNE, ESSENTIAL CLINICAL ANATOMY, 3RD ED., LIPPINCOT WILLIAMS AND WILKINS, 2007. 4. MOORE, KEITH L., CLINICALLY ORIENTED ANATOMY, AND WILKINS, 1982.

CLINICAL ANATOMY: THE BACK CASE ANALYSIS: The Problem: You are called to the emergency room to attend to a 24-yr. old male patient who sustained a hacking wound at the upper back. About an hour prior to this ER consultation, the patient was attacked by an unknown assailant using a machete. He was hit at the upper part of his back. On PE, the following are the pertinent findings: 1. Vital signs: BP- 100/70, RR-15/min, PR- 85/min Temp.- 37. 8 2. A gaping wound is noted at the base of the posterior aspect of the neck measuring about 10 cms in length x 1cm in width x 1 cm in depth, and running obliquely from the right side of the base of the neck crossing the midline to the left then downwards to the medial side of the middle left scapula

CLINICAL ANATOMY:THE BACK COURSE INTRODUCTION CASE ANALYSIS: (continuation) Instruction: Encircle the letter of the corresponding best answer. No erasures. You can write on the sides of the questionnaire for your tentative answer. Once you encircle the letter it becomes the final answer. Answers with traces of erasures will be counted against your score. 1. The most superficial muscle at the area traversed by the wound is: a. Latissimus dorsi b. Trapezius c. Rhomboideus major d. None of the above. 2. The most prominent spinous process at this level is called the vertebra prominens. This refers to what vertebra? a. T1 b. T12 c. L1 d. C7

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION CASE ANALYSIS: 3. The muscle mentioned in question # 1 is more associated with which function? a. function of the upper extremity b. function of respiration c. function of maintaining the structural integrity of the spine d. all of the above e. none of the above 4. The muscle mentioned in question #1 belongs to what layer of muscles of the back? a. superficial layer of muscles b. middle layer of muscles c. deep layer of muscles d. none of the above e. All of the above

CLINICAL ANATOMY: THE BACK THE BACK DEFINITION: - Posterior aspect of the trunk inferior to the neck and superior to the gluteal region (buttocks) -region of the body to which the head, neck and limbs are attached.

CLINICAL ANATOMY: THE BACK REGIONS OF THE BACK: 1. Posterior cervical region 2. Scapular region 3. Vertebral region 4. Subscapular region 5. Lumbar region 6. Sacral region

CLINICAL ANATOMY: THE BACK Reasons for studying the back

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK PRESENCE OF THE SPINAL CORD

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK BACK PAIN

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK -LOW BACK PAIN

CLINICAL ANATOMY: THE BACK REASONS FOR STUDYING THE BACK SCOLIOSIS

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION REASONS FOR STUDYING THE BACK DEGREE OF VARYING DEFORMITY OF THE BACK

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION REASONS FOR STUDYING THE BACK AESTHETIC REASON

MUSCLES OF THE BACK CLINICAL ANATOMY THE BACK

CLINICAL ANATOMY THE BACK MUSCLES OF THE BACK 1. Types/Groupings -Extrinsic muscles -Intrinsic muscles 2. Muscle group arrangement - acdg. to functions Extrinsic muscles- for the upper limbs for respiratory functions Intrinsic muscles- for stability and support of vertebral column

CLINICAL ANATOMY MUSCLES OF THE BACK EXTRINSIC MUSCLES -Arranged in Layers 1. First layer -Trapezius muscle -Latissimus Dorsi 2. Second layer -Levator scapulae -Rhomboid major -Rhomboid minor 3. Third layer -Serratus posterior superior -Serratus posterior inferior

CLINICAL ANATOMY THE BACK MUSCLES OF THE BACK -INNERVATIONS a. Extrinsic Muscles: from the anterior (or ventral) rami of the cervical nerves b. Intrinsic Muscles: from posterior rami (or dorsal) rami of the cervical and thoracic nerves.

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES THE FIRST LAYER SUPERFICIAL EXTRINSIC BACK MUSCLES 1. TRAPEZIUS MUSCLE: a. Description b. Origin c. Insertion d. Function e. Relationship to other structures

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES LATISSIMUS DORSI A. Description -flat, broad muscle B. Origin -6 inferior thoracic vertebrae -posterior layer of lumbar fascia -spines of lumbar and thoracic vertebrae and supraspinous ligament -external lip of iliac crest -lower 4 ribs C. Insertion- humerus -Triangle of Auscultation -triangle of Petit

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES STRUCTURES VISUALIZED: 1. lumbodorsal (thoracolumbar fascia) Iliac Crest External Oblique muscle Triangle of Petit

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES SECOND LAYER OF SUPERFICIAL EXTRINSIC BACK MUSCLES -Levator Scapulae -Rhomboideus Major -Rhomboideus Minor

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES 3RD LAYER OF SUPERFICIAL EXTRINSIC MUSCLES OF THE BACK -SERRATUS POSTERIOR SUPERIOR -SERRATUS POSTERIOR INFERIOR

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES 2. INTRINSIC BACK MUSCLES - True back muscles -Innervation: posterior rami of spinal nerves -Act to maintain posture and control vertebral column movements - Groups: -superficial -intermediate -deep

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES SUPERFICIAL LAYER 1. SPLENIUS MUSCLES -splenius capitis -splenius cervicis “Splenion”- bandage -location -Origin: Nuchal ligament ; spinous processes of C7-T3 or T4 -Insertion: Splenius capitis: mastoid process of temporal bone; lateral third of superior nuchal line of occipital bone Splenius cervicis: tubercles of transverse processes of C1-C3 or C4. ACTIONS: 1. Acting together 2. Acting alone

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES SUPERFICIAL INTRINSIC BACK MUSCLES - SPATIAL RELATIONSHIP SPLENIUS MUSCLES -Splenius cervicis -Splenius capitis

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES LIGAMENTUM NUCHAE -extension of supraspinous ligament in the cervical region -bilaminar of fibroelastic tissues -provides midline attachment for muscles -Trapezius -Splenius

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES INTERMEDIATE LAYER OF INTRINSIC MUSCLES -ERECTOR SPINAE MUSCLES, also known as SACROSPINALIS 3 Muscle Column A.ILIOCOSTALIS-lateral column B. LONGISSIMUS-middle column C. SPINALIS-lateral column -chief extensor of the spine -provides stability, localized action and segmental vascular and neural supply

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES ERECTOR SPINAE 1. –spinalis A. CAPITIS b. cervicis c. thoracis 2.-longissimus A. CAPITIS B. cervicis C. thoracis 3.-iliocostalis a. CERVICIS b. THORACIS c. LUMBORUM

LONGISSIMUS MUSCLE CLINICAL ANATOMY: THE BACK INTRINSIC BACK MUSCLES ERECTOR SPINAE MUSCLES LONGISSIMUS

CLINICAL ANATOMY: THE BACK THE BACK MUSCLES

CLINICAL ANATOMY: THE BACK INTRINSIC BACK MUSCLES THE TRANSVERSO-SPINALIS MUSCLES IN RELATION TO THE ERECTOR SPINAE TRANSVERSO-SPINAL MUSCLES Arranged in layers 1st layer: Semispinalis 2nd layer: Multifidus 3rd layer: Rotatores -known as “gutter muscles” -Obliquely oriented muscles - Origin: transverse processes of the inferior vertebra - Insertion: Spinous processes of the superior vertebra

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES DEEP LAYER OF INTRINSIC BACK MUSCLES Deep to the Erector spinae muscles Obliquely disposed group of muscles TRANSVERSOSPINAL muscle group Occupy the “gutter” between the collective transverse and spinous processes Origin: transverse processes of vertebrae and pass to the spinous processes of more superior vertebrae. composed of : SEMISPINALIS, MULTIFIDUS AND ROTATORES

CLINICAL ANATOMY: THE BACK INTRINSIC BACK MUSCLES TRANSVERSO-SPINALIS MUSCLES The Semispinalis muscles -Semispinalis capitis Responsible for the bulge at each side of the posterior neck near the median plane -Semispinalis cervicis -Semispinalis thoracis

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES

CLINICAL ANATOMY: THE BACK INTRINSIC BACK MUSCLES TRANSVERSO-SPINAL MUSCLES THE ROTATORES -Deepest of the transverso-spinal muscles - Consist of two bundles: the Rotatores longus and Rotatores brevis -Best developed in thoracic vertebrae -Originate from the transverse process of one vertebra below - Insertion: root of the spinous process of the vertebra above. THE ROTATORES

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES MINOR DEEP LAYER OF INTRINSIC MUSCLES/SHORT SEGMENTAL GROUP OF MUSCLES 1. INTERSPINALES 2. INTERTRANSVERSARII 3. LEVATORES COSTARUM -smallest of the deep back muscles -connect one vertebra to another -interspinales connect spinous process of the cervical and lumbar vertebrae -intertransversarii connect the transverse process of the cervical and lumbar vertebrae -levatores costarum connect the tips transverse processes of C7 and T1-T11.

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION GUIDELINES FOR DISECTION OF THE BACK Midline incision from occipital protuberance to the coccyx Transverse incision from the upper end of the line to the mastoid process Third incision: from it lower end, along the crest of the ilium to about its middle 4th incision: extending obliquely from the spinous process of the last thoracic vertebra, upward and outward to the acromion process. LINES OF DISECTION

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION GUIDELINES FOR DISSECTION - Take note the following structures: a. SUPERFICIAL FASCIA b. DEEP FASCIA c. MUSCLES: THE SUPERFICIAL MUSCLES a. Trapezius b. Latissimus dorsi c. Rhomboideus-major and minor d. Levator scapulae d. Different triangular spaces a. Lumbar triangle b. Triangle of Auscultation

CLINICAL ANATOMY: THE BACK COURSE INTRODUCTION GUIDELINES FOR DISSECTION e. THORACOLUMBAR (LUMBODORSAL )FASCIA d. INTRINSIC MUSCLES OF THE BACK 1. cervical region: a. Splenius Capitis b. Splenius Cervicis 2. trunk region: a. Erector Spinae (Sacrospinalis) - Iliocostalis - Longissimus - Spinalis

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN Extends from the cranium to the apex of the coccyx Main part of the axial skeleton Forms the skeleton of the neck and back Functions: -protective osseous structure of vital organs -pivot for the head -weight support -important role in posture and locomotion

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN COMPOSITION OF THE VERTEBRAL COLUMN - Total no. of vertebrae: 33 - Vertebral regions: 5 a. Cervical: 7 vertebrae b. Thoracic: 12 vertebrae c. Lumbar: 5 vertebrae d. Sacral: 5 vertebrae e. Coccyx: 4 vertebrae - Variations: cervical region Lumbarization Sacralization

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN STRUCTURE VS. FUNCTION - Partly rigid axis of the body -Pivot for the head - weight bearing structure - Flexibility: multiple joints shallow- S shaped structure variations in regional flexibility - Height contribution

CLINICAL ANTOMY: THE BACK THE VERTEBRAL COLUMN STRUCTURE AND FUNCTION OF A TYPICAL VERTEBRA “Typical” vertebrae: mid lumbar vertebra PARTS: -Body -Vertebral Arch -7 processes -1 median spinous processes -2 transverse processes -4 articular processes (2 superior and 2 inferior)

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CERVICAL SPINE REGION CHARACTERISTIC REGIONAL DIFFERENCES IN THE VERTEBRAE CERVICAL REGION: -Transverse foramen -spinous processes (C3-C6): short and bifid with 2 knobs on their tips -vertebral notches: almost same size -C1, C2 and C7: atypical cervical vertebrae CERVICAL SPINES

CLINICAL ANATOMY: THE BACK THE CERVICAL SPINE ARTICULATED CERVICAL SPINE: Take note: -Articular processes: superior facets directed superoposteriorly; the inferior facets directed inferoanteriorly Vertebral body: Increasing body size distally Vertebral canal In C7: transitional characteristics

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CHARACTERISTIC REGIONAL DIFFERENCES IN THE VERTEBRAE THE THORACIC REGION - articulation with ribs -long and slender spinous processes -First 4 thoracic vertebrae: -with cervical features -Second 4 thoracic vertebrae: -typical vertebrae -last 4 thoracic vertebrae: -atypical vertebrae

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CHARACTERISTIC REGIONAL DIFFERENCES IN VERTEBRAE THE LUMBAR VERTEBRAE: - “small of the back: prominent spinous processes when the back is flexed -large bodies -absence of costal facets -kidney-shaped vertebral bodies and oval to triangular vertebral foramina -5th LUMBAR VERTEBRA: -largest of all movable vertebrae -stout transverse process

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CHARACTERISTIC REGIONAL DIFFERENCES IN VERTEBRAE THE SACRUM - 5 fused sacral vertebrae - pelvic (ventral) and dorsal surfaces: presence of 4 pairs of foramina -ventral surface: 4 transverse lines -dorsal surface: 5 prominent longitudinal ridges -median sacral crest -intermediate sacral crest -lateral -LUMBOSACRAL ANGLE

CLINICAL ANATOMY: THE BACK surface anatomy 1. spinal Curvatures -CERVICAL LORDOSIS - THORACIC KYPHOSIS - LUMBAR LORDOSIS - SACRAL KYPHOSIS SPINAL CURVATURES

CLINICAL ANATOMY: THE BACK surface anatomy THE CURVATURES Thoracic and sacral curvatures - primary curves - develop during fetal period - retained throughout life as consequence of differences in height between the anterior and posterior parts of the vertebrae.

CLINICAL ANATOMY: THE BACK SURFACE ANATOMY PALPABLE STRUCTURES OF THE BACK Superior Nuchal line External Occipital Protuberance Superior border of the trapezius Clavicle Acromioclavicular joint Vertebra prominens (C7) Scapular spine Inferior angle of the scapulae Spinous processes of the thoracic vertebrae Ribs Bulge of the erector spinae Iliac crest Posterior Superior Iliac Spines

CLINICAL ANATOMY: THE BACK SURFACE ANATOMY

CLINICAL ANATOMY: THE BACK SURFACE ANATOMY

CLINICAL ANATOMY: THE BACK SURFACE ANATOMY

CLINICAL ANATOMY: THE BACK SURFACE ANATOMY

CLINICAL ANATOMY: THE BACK surface anatomy LANDMARK STRUCTURES -Iliac crests -Dimples -Posterior median furrow -Intergluteal cleft

CLINICAL ANATOMY: THE BACK surface anatomy

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN RADIOLOGY OF THE SPINE -Relationship of C1 to C2 vertebrae -anteroposterior view -structures shown in this view: - DENS of the axis at the center - the LATERAL MASS at each side of the DENS - C2 vertebral body -lateral ATLANTOAXIAL JOINT -SPACE between the dens and the lateral masses

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN AP (ANTEROPOSTERIOR) VIEW OF THE CERVICAL SPINE: -STRUCTURES VISUALIZED: - Vertebrae C3-T3 - Lateral masses of the cervical spines -1st to 3rd posterior thoracic ribs -the proximal 1/3 of the clavicles -” tear drop outline of the spinous processes of C3 to T3 - radiolucent column of air at the center of the cervicothoracic vertebral column representing air inside the trachea

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN RADIOLOGY OF THE SPINE LATERAL VIEW OF THE SPINE -STRUCTURES SHOWN a. -bodies of the cervical vertebrae -uniform height -the anterior and posterior borders of the vertebral bodies b. -spinous process -anterior border of the spinous processes c. intervertebral disc spaces d zygapophyseal (facet) joints

CLINICAL ANATOMY: THE BACK RADIOLOGY OF THE SPINE IMPORTANT BONY AND SOFT TISSUE OUTLINES of the cervical spine 1. Collective outlines of: a. anterior border of the vertebral bodies b. posterior border of the vertebral bodies c. anterior border of the spinous process 2. Distance between anterior inferior corner of vertebra above to the anterior superior corner of the vertebra below. 3. Distance between the anterior border of the cervical vertebral bodies to the anterior prevertebral soft tissue outline

CLINICAL ANATOMY: THE BACK RADIOLOGY OF THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK RADIOLOGY

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN RADIOLOGY OF THE SPINE Posteroanterior view of the last three thoracic vertebrae Structures Visualized -ribs -spinous process -pedicle -transverse processes

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN RADIOLOGY OF THE SPINE LATERAL VIEW OF THE LUMBAR SPINE Structures visualized -The vertebral bodies - Intervertebral discs - Intervertebral foramina -zygapophyseal (facet) joints -sacral promontory

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE JOINTS OF THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN JOINTS OF THE VERTEBRAL COLUMN -Symphyses joints (secondary cartilaginous joints) -designed for weight bearing -considerable strength -flexibility 1. -INTERVERTEBRAL DISC (IV DISC) 2. -ZYGAPOPHYSEAL JOINTS 3. -Cervical spine (C3-C6): UNCOVERTEBRAL JOINTS OF LUSCHKA 4. -CRANIOVERTEBRAL JOINTS: -Atlanto-Occipital joints -Atlantoaxial joints

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN JOINTS OF THE VERTEBRAL COLUMN THE CRANIOVERTEBRAL JOINTS: -The atlanto-occipital joints: between the ATLAS (C1) and the Occipital bone of the cranium - The atlantoaxial joints: between the C1 and C2 vertebrae

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN JOINTS OF THE VERTEBRAL COLUMN THE ATLANTOAXIAL JOINTS: 3 articulations: - 2(right and left) lateral atlantoaxial joints between the lateral masses of C1 and the superior facets of C2 - one median atlantoaxial joint between the DENS of C2 and the ANTERIOR ARCH and the TRANSVERSE LIGAMENT of the ATLAS.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN JOINTS OF THE VERTEBRAL COLUMN THE UNCOVERTEBRAL JOINTS OF LUSCHKA -found at the lateral and posterolateral margin of the cervical IV discs of C3-C6 -joints between the uncinate processes of C3-C6 and the bevelled inferolateral surfaces of the vertebral bodies superior to them

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE CERVICAL SPINE -THE JOINT OF LUSCHKA -RELATIONSHIP OF THIS JOINT TO THE INTERVERTEBRAL FORAMINA AND THE CERVICAL NERVE ROOT. - RELATIONSHIP OF THIS JOINT TO THE CERVICAL INTERVERTEBRAL DISC -EFFECT OF THIS JOINT IN DISEASE CAUSATION

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN Joints of the VERTEBRAL COLUMN THE INTERVERTEBRAL DISCS PARTS: _central NUCLEUS PULPOSUS -peripheral ANNULUS FIBROSUS

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INTERVERTEBRAL DISC -The ANNULUS FIBROSUS -Multiple concentric layers of the collagen -orientation of each collagen fibers as depicted by angle theta is about 65 degrees from the vertical.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INVERTEBRAL DISC -The Intervertebral Disc as a Hydrostatic Shock Absorber - 80% of the load: carried through the interbody joint - 20% carried by the posterior structures like the zygapophyseal joints and laminae.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INTERVERTEBRAL DISC WATER CONTENT WITHIN THE INTERVERTEBRAL DISC: INFLUENCE OF DIURNAL AND AGE-RELATED CHANGES IN OVERALL HEIGHT: -Sleeping: low pressure + hydrophilic nature of IVD -attraction of water into the annulus fibrosus and the nucleus pulposus -IVD slightly swollen -overall height: relatively increase -Awake and Upright: high intradiscal pressure---- water is forced out -IVD contracted -Cycle of nocturnal swelling and daytime contraction of IVD: produces an average daily variation in overall height of 1.1%. -One is actually taller in the morning -about 56% of the total loss in height during the day is recovered after only 2 hours of bed rest

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN INTERVERTEBRAL DISC STRUCTURE IN RELATION TO AGE -Less proteoglycan content -aged disc with more collagen but less elastin -occurrence of microfracture -permanent age-related loss of vertebral height

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INTERVERTEBRAL DISC CLINICAL CORRELATION: -HERNIATED NUCLEUS PULPOSUS (HNP) -formal name for a ruptured or slipped disc -direction: usually posterolaterally or posteriorly -one major cause of BACK PAIN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN HERNIATED NUCLEUS PULPOSUS TYPES OF DISC HERNIATIONS -Protrusion -Prolapse -Extrusion -Sequestration

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN HERNIATED NUCLEUS PULPOSUS PATHOMECHANICS OF HERNIATION 1. Involvement of a very large, sudden compression force delivered over the lumbar spine that is flexed or, most likely, flexed and axially rotated(twisted). -associated with single event like a fall or lifting of a large load 2. Involves a series of multiple, low magnitude compression forces, often over a flexed lumbar spine

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN FACTORS THAT FAVOR DISC HERNIATION IN THE LUMBAR SPINE 1. Propensity for fissures or tears in the posterior annulus that allows a path for the flow of nuclear material 2. Sufficiently hydrated nucleus structurally capable of exerting high pressure 3. inability of the posterior annulus to resist high magnitude of radial pressure from the nucleus 4. axial loading applied over a bent (flexed) and twisted spine.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN LIGAMENTS OF THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK LIGAMENTS OF THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK VERTEBRAL COLUMN LIGAMENTS OF THE VERTEBRAL COLUMN Ligamentum flavum -attachments: between the anterior surface of one lamina and the posterior surface of the lamina below. -function: limits flexion -contains a high percentage of elastin; lies posterior to the spine; thickest in the lumbar region.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE LIGAMENTS OF THE VERTEBRAL COLUMN The SUPRASPINOUS AND INTERSPINOUS LIGAMENTS -Attachments: Between the adjacent spinous processes from C7 to the sacrum -function: limit flexion

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE LIGAMENTS OF THE VERTEBRAL COLUMN THE ANTERIOR LONGITUDINAL LIGAMENT -attachments: between the basilar part of the occipital bone and the entire length of the anterior surfaces of all vertebral bodies, including the sacrum. -function: adds stability to the vertebral column and limits extension of excessive lordosis in the cervical and lumbar regions

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE LIGAMENTS OF THE VERTEBRAL COLUMN THE INTERTRANSVERSE LIGAMENT -attachment: between adjacent transverse processes. -function: limits contralateral flexion - few fibers exist in cervical region; in the thoracic region the ligaments are rounded and intertwined with the local muscles; in the lumbar region, these ligaments are thin and membranous.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN LIGAMENTS OF THE VERTEBRAL COLUMN POSTERIOR LONGITUDINAL LIGAMENT. -attachment: throughout the length of the posterior surface of all vertebral bodies between the axis (C1) and the sacrum - function: Adds vertical stability to the vertebral column -limits flexion -reinforces the posterior annulus fibrosus

CLINICAL ANATOMY: THE BACK THE SPINE LIGAMENTS COMPARATIVE STRENGTH OF THE LIGAMENTS IN RELATION TO THE RSTRAINING MOTION IN THE VERTEBRAL SEGMENT -Main restraint: from LIGAMENTUM FLAVA and the CAPSULES of the APOPHYSEAL JOINTS - Ligamentum flava + capsules of the apophyseal joints= 52% of restraint in the lumbar region - Posterior ligament: stiffest ligament - Supraspinous ligament: the most flexible ligament - Anterior longitudinal ligament and the capsules of the apophyseal joints: among the strongest ligamentous tissues in the body -Posterior longitudinal ligament and the Interspinous ligament: among the weakest.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN NEURAL ARCH LIGAMENTS - Ligamentum flavum - Interspinous ligament - supraspinous ligament - Intertransverse lig. -These ligaments are now regarded as one functional unit.

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE LIGAMENTS OF THE VERTEBRAL COLUMN THE JOINT CAPSULES -attachment : margin of .each apophyseal joint -function: strengthens and support the apophyseal joint -becomes taut at the extremes of intervertebral motions, except for extension

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN LIGAMENTS OF THE VERTEBRAL COLUMN Connective tissues that may limit motions of the vertebral column: FLEXION: -Ligamentum nuchae -Interspinous and supraspinous ligaments -Ligamentum flava -Capsule of the apophyseal joint -Posterior annulus fibrosus -Posterior longitudinal ligament

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CONNECTIVE TISSUES THAT MAY LIMIT MOTIONS OF THE VERTEBRAL COLUMN EXTENSION: -Cervical viscera (trachea and esophagus -Anterior annulus fibrosus -Anterior longitudinal ligament

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CONNECTIVE TISSUES THAT MAY LIMIT MOTIONS OF THE VERTEBRAL COLUMN AXIAL ROTATION: -Annulus fibrosus -Capsule of the apophyseal joints -Alar ligaments in the CRANIOCERVICAL region

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CONNECTIVE TISSUES THAT MAY LIMIT MOTIONS OF THE VERTEBRAL COLUMN LATERAL FLEXION: -Intertransverse ligament -Contralateral annulus fibrosus -capsule of the apophyseal joints

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE TYPICAL INTERVERTEBRAL JUNCTION (THE VERTEBRAL COLUMN SEGMENT)

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INTERVERTEBRAL JUNCTION 3 PARTS: 1. SPINOUS PROCESS and the TRANSVERSE PROCESSES 2. APOPHYSEAL JOINTS 3. INTERBODY JOINT -All three share common functions, although each has predominant function

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE INTERVERTEBRAL JUNCTION THE SPINOUS AND TRANSVERSE PROCESSES -function as outriggers, or lever

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN INTERVERTEBRAL JUNCTION THE APOPHYSEAL JOINT -responsible for guiding intervertebral motion - 24 pairs of apophyseal joints -classified as plane joints

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN THE APOPHYSEAL(OR, ZYGAPOPHYSEAL) JOINTS Factors influencing the direction of the intervertebral motion 1. Geometry of articular facets 2. size 3. Orientation of the articular facets Factors influencing the predominant motion in the spinal regions: 1. Size of the Intervertebral disc 2. Size of the vertebrae 3. Local muscle action 4. Attachments of ribs and ligaments.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN STRUCTURE AND FUNCTION OF THE APOPHYSEAL JOINTS(or, ZYGAPOPHYSEAL JOINTS) - Act as mechanical barricades -permit certain movements and block others.

THE INTERVERTEBRAL JUNCTION TERMINOLOGY DESCRIBING THE JOINT KINEMATICS AT THE APOPHYSEAL JOINTS “separation (gapping) between joint surfaces”- an articular surface tends to move away from its partner facet. Joint separation is usually caused by distraction force Ex: therapeutic traction CLINICAL ANATOMY: THE BACK

THE INTERVERTEBRAL JUNCTION TERMINOLOGY DESCRIBING JOINT KINEMATICS AT THE APOPHYSEAL JOINT “approximation of joint surfaces”- an articular facet surface tends to move closer to its partner facet. Joint approximation is usually caused by a compression force. Example: Extension or increased lordosis of the lumbar spine. CLINICAL ANATOMY: THE BACK

THE INTERVERTEBRAL JUNCTION TERMINOLOGY DESCRIBING THE JOINT KINEMATICS AT THE APOPHYSEAL JOINTS “sliding(gliding) between joint surfaces”- An articular facet translate in a linear or curvilinear direction within the plane of the joint. -the sliding between joint surfaces is caused by a force directed tangential to the joint surfaces -Sliding between joint surfaces is resisted by a shear force -EX: flexion-extension of the mid to lower cervical spine CLINICAL ANATOMY: THE BACK

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN INTERVERTEBRAL JUNCTION INTERBODY JOINT(the INTERVERTEBRAL DISC) -functions primarily for shock absorption and load distribution -adds stability to the spine

CLINICAL ANATOMY: THE BACK: THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN

CLINICAL ANATOMY: THE BACK THE SPINAL CORD

Clinical anatomy: the back the spinal cord THE SPINAL CORD A. Ave. length(European males): 45 cms. B. Ave weight: 30 g. C. Proximal end: upper border of the atlas D. Distal end: In front of the intervertebral disc between L1 and L2. E. occupies 2/3 of the vertebral canal

CLINICAL ANATOMY: THE BACK THE SPINAL CORD Major reflex center and conduction pathway between the body and the brain Begins as a continuation of the medulla oblongata (commonly called the medulla), the caudal part of the brainstem. Adult: the spinal cord usually ends opposite the intervertebral disc of L1 and L2 vertebrae Newborn: the inferior end of the spinal cord usually is opposite the IV disc of L2 and L3 vertebrae.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD STRUCTURES THAT PROTECT THE SPINAL CORD 1. Osseous vertebral column 2. Surrounding soft tissues like the muscles 3. Ligaments 4. Meninges 5. Cerebrospinal fluid

CLINICAL ANATOMY: THE BACK THE SPINAL CORD SPINAL ENLARGEMENTS A. CERVICAL: - from 3rd cervical to the 2nd thoracic segments. -max. circumference: 38 mm at the level of C6. B. LUMBAR: - from the L1 to S3 - max. circumference: 35 mm at the level of T12 body.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD SPINAL MENINGES -Collectively: spinal meninges -dura mater -arachnoid mater -pia mater DURA MATER -tough, fibrous and elastic tissue -outer most covering -separated from the vertebrae by the EPIDURAL SPACE -attachments: foramen magnum; sides of the vertebral canal; filum terminale

CLINICAL ANATOMY: THE BACK THE SPINAL CORD THE SPINAL MENINGES

CLINICAL ANATOMY: THE BACK THE SPINAL CORD THE SPINAL MENINGES THE ARACHNOID MATER -delicate, avascular membrane -lines the dural sac and the dural root sheath -encloses the SUBARACHNOID SPACE -THE PIA MATER -innermost covering -directly covers the spinal cord and the roots of spinal nerves and spinal blood vessels. -inferior to the conus medullaris, the pia continues as the TERMINAL FILUM.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD SUBARACHNOID SPACE -an actual space that lies between the arachnoid and the pia mater -filled with CSF - the enlargement of the subarachnoid space in the dural sac, caudal to the medullary cone and containing CSF and the CAUDA EQUINA is called the LUMBAR CISTERN.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD CLINICAL CORRELATION LUMBAR SPINAL PUNCTURE - to obtain a sample of CSF from the lumbar cistern for the following intentions 1. diagnostic procedures -myelogram -for CSF studies: CSF sample for culture and sensitivity test in bacterial meningitis 2. Introduction of anesthestic agent -EPIDURAL BLOCK

CLINICAL ANATOMY: THE BACK THE SPINAL CORD CLINICAL CORRELATION MYELOGRAM - HNP - SPINAL TUMORS - SPINAL FRACTURES

CLINICAL ANATOMY: THE BACK THE SPINAL CORD CLINICAL CORRELATION MYELOGRAM OR MYELOGRAPHY -Introduction of contrast media into the subarachnoid space to outline the following structures: -nucleus pulposus -the spinal cord -the spinal nerve roots and nerves

Clinical anatomy: the back the spinal cord CEREBROSPINAL FLUID 1. Composition and secretion - clear, colorless liquid - differs from blood in its electrolyte content and its very small amount of protein - actively secreted by the choroid plexus - total volume: 150 ml -25 ml in the lateral ventricles -100 ml in the cranial subarachnoid space - 25 ml in the spinal subarachnoid space

CLINICAL ANATOMY: THE BACK THE SPINAL CORD THE SPINAL NERVE Characteristics: -united ventral and dorsal spinal roots -loosely termed “nerve root” - 31 pairs 8 cervical 12 thoracic 5 lumbar 5 sacral 1coccygeal

CLINICAL ANATOMY: THE BACK THE SPINAL CORD SPINAL ROOTS AND GANGLIA 1. VENTRAL (ANTERIOR) ROOTS - contain efferent somatic and, in some levels, efferent sympathetic , nerve fibers 2. DORSAL(POSTERIOR) ROOTS: -afferent axons(both somatic and visceral) from unipolar neurones in spinal ganglia. 3. DORSAL GANGLIA

Clinical anatomy: the back the spinal cord FISSURES AND SULCI - Anterior median fissure -Posterior median sulcus - Posterolateral sulcus - Dorsal roots(Strictly rootlets) - Funiculi

CLINICAL ANATOMY: THE BACK THE SPINAL CORD

CLINICAL ANATOMY: THE BACK THE SPINAL CORD APPEARANCE OF ROOTS AT EACH SPINAL LEVEL Cervical Region: -1st upper 4 cervical: small - lower or distal 4 cervical roots: large - thickness ratio of cervical dorsal roots to the ventral roots: 3:1 -exception: 1st cervical dorsal root: smaller than the ventral root; occasionally absent.

Clinical anatomy: the back the spinal cord APPEARANCE OF THE SPINAL ROOTS AT EACH SPINAL LEVEL THORACIC REGION: -thoracic roots are small with the exception of the 1st thoracic root. -dorsal roots only slightly exceed the ventral roots in thickness - successively increase in length

CLINICAL ANATOMY: THE BACK THE SPINAL CORD APPEARANCE OF THE SPINAL ROOTS AT EACH SPINAL LEVEL LUMBAR AND SACRAL REGIONS -lower lumbar and upper sacral roots: the largest; their rootlets are most numerous - coccygeal roots: the smallest - lumbar, sacral and coccygeal roots descend with increasing obliquity to their exits CAUDA EQUINA: collection of spinal roots of the lower lumbar, sacral and coccygeal roots at the distal part of the spinal cord.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD

CLINICAL ANATOMY: THE BACK THE SPINAL CORD

CLINICAL ANATOMY: THE BACK THE SPINAL CORD 1. COVERINGS AND RELATIONS OF THE SPINAL ROOTS , SPINAL NERVES IN THE RADICULAR CANAL 2. CLINICAL CORRELATION

CLINICAL ANATOMY: THE BACK THE SPINAL CORD THE RAMI OF THE SPINAL NERVES Ventral (anterior) rami - generally larger than dorsal rami -supply the limbs and the anterolateral aspects of the trunk Dorsal( posterior) rami: - usually smaller - supply the muscles and skin of the posterior regions of the neck and trunk

CLINICAL ANATOMY: THE BACK THE SPINAL CORD CERVICAL VENTRAL RAMI Upper four cervical ventral rami: form the cervical plexus Lower four cervical ventral rami: together with most of the first thoracic ventral ramus form the BRACHIAL PLEXUS.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD VARIATIONS OF SPINAL RAMI Cervical Dorsal Spinal Rami - divisions: medial and lateral branches - structures innervated: -medial branch of 2nd to 4th, and usually the 5th cervical posterior rami supply the skin - semispinalis capitis and semispinalis cervicis

CLINICAL ANATOMY: THE BACK THE SPINAL CORD FIRST CERVICAL DORSAL RAMUS (SUBOCCIPITAL NERVE) - larger than the ventral ramus - structures innervated: -rectus capitis posterior major and minor -obliquus capitis superior and inferior -semispinalis capitis

CLINICAL ANATOMY: THE BACK SUBOCCIPITAL AND DEEP NECK MUSCLES THE SUBOCCIPITAL REGION -Superior part of the back of the neck- is the triangular area(SUBOCCIPITAL TRIANGLE) inferior to the occipital region of the head, including the posterior aspects of C1 and C2 vertebrae. SUBOCCIPITAL TRIANGLE: lies deep to the trapezius and semispinalis capitis muscle. 4 muscles in the suboccipital region: rectus capitis posterior major and minor; superior and inferior oblique -innervation: posterior rami of C1-SUBOCCIPITAL NERVE -mainly postural muscles STRUCTURES INSIDE THE SUBOCCIPITAL TRIANGLE

CLINICAL ANATOMY: THE BACK THE SPINAL CORD SECOND CERVICAL DORSAL RAMUS -slightly bigger than the ventral ramus -larger than all the cervical dorsal rami Branches: 1. large medial branch -termed “greater occipital nerve -supplies: a. inferior oblique b. semispinalis capitis c. trapezius d. skin of the scalp as far as the vertex e. back of the auricle 2. small lateral branch -supplies : - splenius capitis -longissimus capitis -semispinalis capitis CLINICAL CORRELATION: Greater Occipital Neuralgia

Clinical anatomy: the back the spinal cord THE THIRD CERVICAL DORSAL RAMUS DESCRIPTION: -Intermediate in size between the 2nd an 4th BRANCHES: 1. Medial -Structures Innervated: Spinalis capitis, semispinalis cervicis; splenius; trapezius -skin of the lower occipital region through the THIRD OCCIPITAL NERVE 2. Lateral : joins a branch of the 2nd cervical dorsal ramus POSTERIOR CERVICAL PLEXUS: composed of the dorsal ramus of the SUBOCCIPITAL NERVE AND MEDIAL BRANCHES of the DORSAL RAMI of the 2ND AND 3RD CERVICAL NERVES which are joined by loops.

CLINICAL ANATOMY: THE BACK THE SPINAL CORD DORSAL RAMI OF THE LOWER 5 CERVICAL NERVES Branches 1. medial branch: -semispinalis cervicis; semispinalis capitis; splenius; trapezius -4th: end in skin -5th: may not reach the skin -medial branch of the 6th, 7th, 8th cervical dorsal rami -semispinalis cervicis -semispinalis capitis -multifidus -interspinales 2. lateral branches -Iliocostalis cervicis -longissimus cervicis -longissimus capitis

CLINICAL ANATOMY: THE BACK THE SPINAL CORD THORACIC DORSAL SPINAL RAMI Branches: 1. Medial branches - upper 6 thoracic dorsal rami supply: -semispinalis thoracis and multifidus -rhomboids and trapezius -skin near the vertebral spines -lower 6 thoracic dorsal rami supply mainly: - multifidus -longissimus thoracis -occasionally the skin in the median region 2. Lateral branches -supply the : Longissimus thoracis; Iliocostalis cervicis, and levatores costarum - lower five or six: cutaneous branch -supply the serratus posterior inferior and latissimus dorsi - upper thoracic: skin - 12th thoracic lateral branch: sends a filament medially along the iliac crest, then passes down to the anterior gluteal skin

CLINICAL ANATOMY: THE BACK THE SPINAL CORD LUMBAR DORSAL RAMI -Branches: 1. Medial branches -supply the multifidus 2. Lateral branches -erector spinae -upper 3 lumbar dorsal rami: supply aponeurosis of the latissimus dorsi, skin at the posterior iliac crest, gluteal skin, greater trochanter. SACRAL DORSAL RAMI -Branches: 1. Medial branch: multifidus 2 Lateral branch: -gluteal maximus -skin: posterior gluteal skin -Dorsal rami of 4th and 5th sacral nerves supply the skin at the coccygeal area together with the coccygeal dorsal ramus -COCYYGEAL DORSAL RAMUS: -No division

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN VASCULATURE OF THE SPINE

CLINICAL ANATOMY: THE BACK VASCULATURE OF SPINE ARTERIES TO THE VERTEBRAL COLUMN -spinal arterial branches supplying the vertebral column: 1. Vertebral and Ascending cervical arteries in the neck 2. Posterior intercostal arteries in the thoracic region 3. Subcostal and lumbar arteries in the abdomen 4. Iliolumbar and lateral and medial sacral arteries in the pelvis.

CLINICAL ANATOMY: THE BACK VASCULATURE OF THE SPINE

Clinical anatomy: the back vasculature of the spine

CLINICAL ANATOMY: THE BACK VASCULATURE OF THE SPINE VENOUS PLEXUSES OF THE SPINE Internal vertebral venous plexus External vertebral venous plexus Basivertebral veins Intervertebral veins

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN VENOUS DRAINAGE Venous plexuses along the vertebral column a. Internal vertebral venous plexus: spinal veins forming venous plexuses inside the vertebral column b. External vertebral venous plexuses: formed by the spinal veins outside of the vertebral column

CLINICAL ANATOMY: THE BACK THE SPINAL CORD VASCULATURE OF SPINAL CORD AND SPINAL NERVE ROOTS BLOOD SUPPLY TO THE POSTERIOR AND ANTERIOR NERVE ROOTS: -Posterior and anterior radicular arteries

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN INNERVATION TO THE SPINE

CLINICAL ANATOMY: THE BACK THE SPINAL CORD

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN NERVES OF VERTEBRAL COLUMN ZYGAPOPHYSEAL JOINTS(APOPHYSEAL or FACET JOINTS): innervated by the articular branches of the medial branches of the posterior rami Vertebral column -innervation: recurrent meningeal branches of the spinal branches.

CLINICAL ANATOMY: THE BACK KINESIOLOGY

CLINICAL ANATOMY: THE BACK KINESIOLOGY TERMINOLOGY: GREEK: Kinesis- to move ology- to study -KINEMATICS: - a branch of mechanics that describes the motion of a body, without regard to the forces or torques that may produce the motion -TYPES OF MOTION: -Translation a.rectilinear b. curvilinear - Rotation

:CLINICAL ANATOMY: THE BACK KINESIOLOGY TERMINOLOGY: OSTEOKINEMATICS -describes the motion of bones relative to the 3 cardinal(principal) planes of the body: -sagittal -frontal -horizontal -the cardinal planes are based on the anatomic position

CLINICAL ANATOMY: THE BACK KINESIOLOGY OSTEOKINEMATICS DEGREES OF FREEDOM -refers to the number of independent movements allowed at a joint. - 3 degrees of freedom -sagittal -frontal -horizontal Example of movements in different body planes: A. SAGITTAL PLANE -flexion and extension -dorsiflexion and plantar flexion -forward and backward bending

CLINICAL ANATOMY: THE BACK KINESIOLOGY OSTEOKINEMATICS - A matter of perspective - a movement of the joint can be considered from two perspective: 1. the proximal segment can rotate against relatively fixed distal segment 2. the distal segment rotating against a fixed proximal segment.

CLINICAL ANATOMY: THE BACK KINESIOLOGY REGIONAL KINEMATICS OF THE SPINE

CLINICAL ANATOMY: THE BACK KINESIOLOGY REGIONAL KINEMATICS OF THE SPINE DEFINITION: -Refers to the range and predominant direction of movements at the various regions of the vertebral column -ZERO or REFERENCE POINT: Resting posture of the region while standing -resting curvature: - cervical lordosis- 30- 35 degrees - thoracic kyphosis- 40 degrees - lumbar lordosis- 45 degrees

CLINICAL ANATOMY: THE BACK KINESIOLOGY THE CRANIOCERVICAL REGION

CLINICAL ANATOMY: THE BACK KINESIOLOGY CRANIOCERVICAL REGION: - “NECK” Combined set of 3 articulations: 1. -ATLANTO-OCCIPITAL 2. -ATLANTO-AXIAL JOINT COMPLEX -median joint - 2 pairs of apophyseal joints. 3. –INTRACERVICAL APOPHYSEAL JOINTS(C2-C7) -Most mobile spinal region -movements subserve the function of vision, hearing, smell and equilibrium

CLINICAL ANATOMY: THE BACK KINESIOLOGY FUNCTIONAL ANATOMY OF THE CRANIOCERVICAL JOINTS THE ATLANTO-OCCIPITAL JOINT -provides independent movement of the cranium relative to the atlas -structures that go into the formation of the joint -stability of the joint -ligaments of the joint -degrees of freedom -primary motions -sagittal flexion -sagittal extension - slight lateral flexion - axial rotation: not a degree of freedom THE ATLANTO-OCCIPITAL JOINT

CLINICAL ANATOMY: THE BACK KINESIOLOGY FUNCTIONAL ANATOMY OF THE CRANIOCERVICAL JOINTS THE ATLANTO-AXIAL JOINT COMPLEX STRUCTURES THAT GO INTO THE FORMATION OF THE JOINT COMPLEX -MEDIAN JOINT -2 APOPHYSEAL JOINT DEGREES OF FREEDOM THE STABILIZING CONNECTIVE TISSUES -TECTORIAL MEMBRANE -ALAR LIGAMENTS

CLINICAL ANATOMY: THE BACK KINESIOLOGY INTRACERVICAL APOPHYSEAL JOINTS - 45-degree facet orientation - provides great freedom of movement in all three planes, a hallmark of cervical articulation.

CLINICAL ANATOMY: THE BACK KINESIOLOGY Flexion- extension occuring in the following craniocervical joints: 1 atlanto-occipital 2. atlanto-axial complex 3. Intracervical region (C2-C7) -20 to 25% of the total sagittal plane motion occurs over the atlanto-occipital and atlanto-axial joint complex - remainder of motion: intracervical region (C2-C7) SAGITTAL PLANE KINEMATICS AT THE CRANIOCERVICAL REGION Flexion-extension arc: 130- 135 degrees Resting neutral posture: 30-35 degrees of extension -from resting neutral posture: additional 85 degrees on active extension - from resting neutral posture: 45-50 degrees on active flexion

CLINICAL ANATOMY: THE BACK KINESIOLOGY REGIONAL KINEMATICS OF THE SPINE SAGITTAL PLANE KINEMATICS AT THE CRANIOCERVICAL REGION- FLEXION and EXTENSION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS OF FLEXION AND EXTENSION

CLINICAL ANATOMY: THE BACK KINESIOLOGY Atlanto-occipital joint: - backward roll of convex occipital condyles within the concave superior facets of the atlas. -simultaneous slide slightly in the direction opposite to the roll - tension in tectorial membrane, articular capsules, and atlanto-occipital membrane limits the extent of the roll and slide of the occipital condyles. - KINEMATICS OF CRANIOCERVICAL EXTENSION INTRACERVICAL ARTICULATION (C2-C7) Initiation of motion -low cervical spine(C4-C7) -70 degrees of extension -full extension: close packed position of cervical apophyseal jonts. -slackening of joint capsule with inferior sliding motion of the inferior facets of the superior vertebrae ATLANTO-AXIAL JOINT: -degrees of freedom: -primarily axial rotation - 15 degrees flexion-extension - osteokinematics:: backward pivot of atlas - restraint to pivot motion of atlas: contact of dens against the median joint of atlanto-axial articulation

CLINICAL ANATOMY: THE BACK KINESIOLOGY OSTEOKINEMATICS OF PROTRACTION AND RETRACTION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS OF FLEXION AND EXTENSION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS OF AXIAL ROTATION AT THE CRANIOCERVICAL REGION

CLINICAL ANATOMY: THE BACK KINESIOLOGY HORIZONTAL PLANE KINEMATICS AT THE CRANIOCERVICAL REGION OSTEOKINEMATICS OF AXIAL ROTATION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS OF AXIAL ROTATION AT THE CRANIOCERVICAL REGION AXIAL ROTATION AT THE INTRACERVICAL ARTICULATIONS (C2-C7)

CLINICAL ANATOMY: THE BACK KINESIOLOGY FRONTAL PLANE KINEMATICS AT THE CRANIOCERVICAL REGION OSTEOKINEMATICS OF LATERAL FLEXION -approximately 40 degrees of lateral flexion -most movement occurs at the C2-C7 region -5 degrees occur at the atlanto-occipital joint - negligible lateral flexion at the atlanto-occipital joint LATERAL FLEXION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS OF LATERAL FLEXION ATLANTO-OCCIPITAL JOINT -small amount of side-to-side rolling of the occipital condyles over the superior facet of the atlas -extremes of lateral flexion: -slight unilateral joint approxiimation on the side of lateral flexion -slight joint separation on the side opposite the lateral flexion LATERAL FLEXION

CLINICAL ANATOMY: THE BACK KINESIOLOGY ARTHROKINEMATICS AT THE INTRACERVICAL ARTICULATION C2-C7 Sliding of the articular facets at the side of flexion Sliding of the articular facets opposite the lateral flexion Mechanical coupling: lateral flexion plus ipsilateral slight axial rotation

REGIONAL KINEMATICS OF THE SPINE KINEMATICS OF THE THORACIC SPINE REGION

CLINICAL ANATOMY: THE BACK KINESIOLOGY THORACIC REGION THORAX: -formed by: -ribs -sternum -thoracic vertebrae -the rigidity of the region provides the ff. functions: 1-a stable base for muscles to control the craniocervical region 2-protection of the intrathoracic region 3 -mechanical bellows for breathing

CLINICAL ANATOMY: THE BACK KINESIOLOGY FUNCTIONAL ANATOMY OF THORACIC ARTICULAR STRUCTURES THORACIC SPINE: -24 apophyseal joints(12 pairs) -bilateral articular facets -restricted movements

CLINICAL ANATOMY: THE BACK KINESIOLOGY KEY ANATOMIC ASPECTS OF THE COSTOVERTEBRAL JOINT Each costovertebral joint -connects the head of a typical rib with a pair of costal facets and the adjacent margin of an intervening intervertebral disc. -is stabilized by radiate and capsular ligament

CLINICAL ANATOMY: THE BACK KINESIOLOGY KINEMATICS AT THE THORACIC REGION KINEMATICS OF FLEXION AT THE THORACIC REGION Approx. 30-40 degrees of flexion -extremes of flexion limited by: 1. the posterior arch ligaments like the supraspinous and interspinous ligaments 2. capsules of the apophyseal joints 3. posterior annulus fibrosus 4. posterior longitudinal lig.

CLINICAL ANATOMY: THE BACK KINESIOLOGY KINEMATICS OF EXTENSION AT THE THORACIC REGION Approx. 20-25 degrees of extension With thoracolumbar coupling: 35 to 40 degrees of extension (a sum of 20 to 25 degrees of thoracic extension and 15 degrees of lumbar extension)

CLINICAL ANATOMY: THE BACK KINESIOLOGY KINEMATICS OF AXIAL ROTATION AT THE THORACIC REGION Approx. 30 degrees of horizontal plane(axial) to each side Freedom of axial rotation decreases in a cranial-to-caudal direction Mid to lower thoracic spine, the greater vertically oriented apophyseal joints tend to block horizontal plane motion.

CLINICAL ANATOMY: THE BACK KINESIOLOGY KINEMATICS OF THORACIC LATERAL FLEXION Approx. 25 degrees to each side Magnitude of this motion relatively constant Mechanical coupling in ipsilateral manner

REGIONAL KINEMATICS OF THE SPINE KINEMATICS AT THE LUMBAR REGION

CLINICAL ANATOMY: THE BACK KINESIOLOGY FUNCTIONAL ANATOMY OF THE ARTICULAR STRUCTURES WITHIN THE LUMBAR SPINE(L1-S5) Facet articular surfaces: 25 degree from the sagittal plane Favors sagittal plane motion at the expense of axial rotation.

CLINICAL ANATOMY: THE BACK KINESIOLOGY FUNCTIONAL ANATOMY -Abrupt change in the facet orientation at or near the thoracolumbar junction - high incidence of traumatic paraplegia in injuries involving the thoracolumbar region

CLINICAL ANATOMY: THE BACK KINESIOLOGY L5-S1 JUNCTION Typical intervertebral junction with an interbody joint anteriorly and a pair of apophyseal joints posteriorly Facet surfaces of L5-S1 apophyses oriented in a more frontal plane Sacrohorizontal angle =40 degrees connective tissues stabilizing the L5-S1 junction 1. Anterior longitudinal ligament 2. Iliolumbar ligaments L5-S1 apophyseal joints resist anterior shear force.

CLINICAL ANATOMY: THE BACK KINESIOLOGY The wide and sturdy articular facets of the L5-S1 apophyseal joints provide bony stabilization to L5-S1 junction LIGAMENTS THAT STABILIZE THE L5-S1 JUNCTION: 1. ANTERIOR LONGITUDINAL LIGAMENT 2. THE ILIOLUMBAR LIGAMENTS

CLINICAL ANATOMY: THE BACK KINESIOLOGY KINEMATICS AT THE LUMBAR REGION APPROX. RANGE OF MOTION FOR THE 3 PLANES OF MOVEMENT FOR THE LUMBAR REGION FLEXION AN D EXTENSION (SAGITTAL PLANE) -FLEXION: 50 DEGREES ----EXTENSION: 15 DEGREES -TOTAL: 65 DEGREES AXIAL ROTATION: 5 DEGREES LATERAL FLEXION (FRONTAL PLANE): 20 DEGREES

CLINICAL ANATOMY: THE BACK KINESIOLOGY THORACOLUMBAR EXTENSION: 20-25 DEGREES OF THORACIC EXTENSION AND 15 DEGREES OF LUMBAR EXTENSION THORACOLUMBAR LATERAL FLEXION: 25 DEGREES THORACIC LATERAL FLEXION; 20 DEGREES OF LUMBAR LATERAL FLEXION

CLINICAL ANATOMY: THE BACK KINESIOLOGY RELATIVE RESISTANCE PROVIDED BY THE LOCAL CONNECTIVE TISSUES TO EXTREME FLEXION IN THE LUMBAR REGION CAPSULE OF THE APOPHYSEAL JOINT: LARGEST RESISTANCE DISC: FOLLOWS 2ND SUPRASPINOUS AND INTERSPINOUS LIGAMENTS-3RD LIGAMENTUM FLAVUM: THE LEAST RESISTANCE. CLINICAL SIGNIFICANCE: IN HEALTHY LOWER BACK, PASSIVE RESISTANCE OFFERED BY THE APOPHYSEAL CAPSULE REDUCES COMPRESSION LOAD ON THE INTERVERTEBRAL DISC.

CLINICAL ANATOMY: THE BACK KINESIOLOGY EXTENSION OF THE LUMBAR REGION Essentially reverse of lumbar flexion Increases lumbar lordosis Full extension increases both the amount of load and area of contact at the apophyseal joints.

CLINICAL ANATOMY: THE BACK KINESIOLOGY

CLINICAL ANATOMY: THE BACK KINSIOLOGY ANTERIOR AND POSTERIOR PELVIC TILT EFFECT IF PELVC TILT ON THE LUMBAR SPINE

CLINICAL ANATOMY: THE BACK KINESIOLOGY Illustration A and C show anterior pelvic tilt or Intervertebral lumbar extension Illustration B and D show posterior pelvic tilt or intervertebral lumbar flexion

CLINICAL ANATOMY: THE BACK KINESIOLOGY LUMBAR FLEXION: Its Effect on the Diameter of the Intervertebral Foramen and Migration of the Annulus Pulposus full lumbar flexion: increases the volume of the vertebral canal by 11% -increases the diameter of the intervertebral foramen by 19% -generates compression force on the anterior side of the disc, which tend to migrate the disc posteriorly

CLINICAL ANATOMY: THE BACK KINESIOLOGY UNDESIRABLE EFFECTS OF EXAGGERATED LUMBAR LORDOSIS -Ex. In residuals of poliomyelitis involving hip flexion contracture -increased compression force on the apophyseal joints -increased anterior shear at the lumbosacral junction leading to spondylolisthesis.

CLINICAL ANATOMY: THE BACK KINESIOLOGY LUMBOPELVIC RHYTHM DURING TRUNK FLEXION LUMBOPELVIC RHYTHM

CLINICAL ANATOMY: THE BACK LUMBOPELVIC RHYTHM DURING TRUNK EXTENSION LUMBOPELVIC RHYTHM

CLINICAL ANATOMY: THE BACK KINESIOLOGY SITTING POSTURE AND ITS EFFECTS ON ALIGNMENT OF THE LUMBAR AND CRANIOCERVICAL REGIONS

CLINICAL ANATOMY: THE BACK KINESIOLOGY

CLINICAL ANATOMY: THE BACK KINESIOLOGY

CLINICAL ANATOMY: THE BACK THE INTRINSIC BACK MUSCLES KINESIOLOGY PRINCIPAL MUSCLES PRODUCING MOVEMENTS OF THE THORACIC AND LUMBAR INTERVERTEBRAL JOINTS

CLINICAL ANATOMY: THE BACK CLINICAL CORRELATION 1. BACK STRAIN -common cause of back pain -results from extreme movements of the vertebral column such as extension or rotation -pathology: stretching and/or microscopic tearing of muscle fibers and/or ligaments of the back -muscle involved: ERECTOR SPINAE -A protective mechanism 2. ISCHEMIA OF THE BRAINSTEM - pathology: reduced blood flow through the winding course of the vertebral arteries through the suboccipital triangle caused by condition like ARTERIOSCLEROSIS. -REDUCED blood flow to the brainstem -s/s: prolong turning of the head-as occurs when backing up a motor vehicle- may cause lightheadedness, dizziness, and other symptoms.

CLINICAL ANATOMY: THE BACK THE VERTEBRAL COLUMN CLINICAL CORRELATION: Rupture of the ALAR LIGAMENTS -may occur with combined flexion and rotation of the head -increase by 30% in the range of movement of the head to the opposite side. Rupture of the TRANSVERSE LIGAMENTS of Atlas -setting free of the DENS -resulting in ATLANTOAXIAL SUBLUXATION or, incomplete dislocation of the median ATLANTOAXIAL JOINT -if complete dislocation of the median atlantoaxial joint occurs, the DENS may be driven into the upper cervical region of the spinal cord causing QUADRIPLEGIA( paralysis of the upper and lower extremities) - the dens may be driven and impinges into the MEDULLA of the BRAINSTEM causing death.