ONIA: Muscles of Mastication

Temporalis Origin

Triangular muscle with broad attachment to floor of temporal fossa and deep surface of temporal fascia

Temporalis Insertion

Narrow attachment to tip and medial surface of coronoid process and anterior border of ramus of mandible

Temporalis Nerve

Anterior trunk of mandibular N (CN V3) Via temporal branches

Temporalis Action

Elevates mandible; Side to side (grinding)

Masseter Origin

Quadrate muscle attaching to inferior border and medial surface of maxillary process of zygomatic bone and the zygomatic arch

Masseter Insertion

Angle and lateral surface of ramus of mandible

Masseter Nerve

Ant. Trunk of mandibular N (CN V3) Via masseteric nerve

Masseter Action

Elevates mandible; minimal side to side movement

Lateral pterygoid Origin

Triangular two headed muscle from (1) infratemporal surface and crest of greater wing of sphenoid and (2) Surface of lateral pterygoid plate

Lateral pterygoid Insertion

Superior head: joint capsule and articular disc of TMJ; Inferior head: pterygoid fovea on anteromedial aspect of neck of condyloid process of mandible

Lateral pterygoid Nerve

Ant. Trunk of mandibular N (CN V3) via lateral pterygoid N.

Lateral pterygoid Action

Bilateral: Protrusion of jaw opening

Unilateral: Protrusion to opposite side; stabilizes condylar head against articular eminence during closure

Medial pterygoid Origin

Quadrangular two-headed muscle from (1) medial surface of lateral pterygoid plate and pyramidal process of palatine bone (2) tuberosity of maxilla

Medial pterygoid Insertion

Medial surface of ramus of mandible inferior to mandibular foramen

Medial pterygoid Nerve

Main trunk of mandibular N. (CN V3) via medial pterygoid N

Medial pterygoid Action

Elevates mandible; bilateral: with lateral pterygoid protrudes mandible; unilateral: protrudes mandible to opposite side for side-side grinding