Muscles of mastication Kritchai Bespinyowong

Contents Temporal fossa Infratemporal fossa Muscles of mastication

Temporal fossa Above & behind - superior temporal line Anterior wall - zygomatic bone - zygomatic process of frontal bone - greater wing of sphenoid bone Medial wall - parietal bone - frontal bone - squamous part of temporal bone - greater wing of sphenoid bone “Pterion” : middle meningeal artery Inferior - infratemporal crest of sphenoid bone

Infratemporal fossa Anterior wall - posterior surface of maxilla - maxillary tuberosity Medial wall - lateral pterygoid plate of sphenoid bone - pyramidal process of palatine bone Lateral wall - inner surface of zygamatic arch - upper part of ramus of mandible - coronoid process of mandible Roof - infratemporal surface of sphenoid bone - infratemporal surface of squamous temporal bone

Muscles of mastication กล้ามเนื้อบดเคี้ยว Develop from mesoderm of 1st branchial arch Nerve supply : branches from V3 Masseter muscle Temporalis muscle Medial pterygoid muscle Lateral pterygoid muscle

Masseter muscle

Masseter muscle

Masseter muscle Superficial portion Deep portion

Masseter muscle Nerve supply : Nerve to masseter Action : 1. Elevation (bilateral) 2. Retrusion (bilateral) 3. Ipsilateral excursion (unilateral)

Temporalis muscle

Temporalis muscle

Temporalis muscle

Temporalis muscle Nerve supply : Deep temporal branches of mandibular nerve Action : 1. Resting tonus (bilateral) 2. Elevation (bilateral) 3. Retrusion (bilateral) 4. Ipsilateral excursion (unilateral)

Temporal fascia

Temporal fascia

Medial pterygoid muscle

Medial pterygoid muscle

Medial pterygoid muscle Nerve supply : Medial pterygoid nerve Action : 1. Elevation (bilateral) 2. Protrusion (bilateral) 3. Contralateral excursion (unilateral)

Lateral pterygoid muscle

Lateral pterygoid muscle Nerve supply : Nerve to lateral pterygoid Action : 1. Protrusion (bilateral) 2. Depression (bilateral) 3. Contralateral excursion (unilateral)

Opening and closing movement

Protrusion and Retrusion

Lateral movement

Lab directions Bones - Temporal fossa - Infratemporal fossa Origin and insertion Cadaver - Masseter muscle Superficial temporal artery - Superficial temporal vein - Auriculotemporal nerve - Temporal fascia - Temporalis muscle