General features:
- They are developed from the 1st pharyngeal arch.
- The main function is to facilitate the movement of the jaw during mastication & other oral activities.
- They are innervated by the mandibular division (V₃) of the trigeminal n.(V).
Table 8.11 Muscles of mastication
Only this muscle has the option of open the mouth.
① Masseter m. :
(strong quadrangular m.)
Superficial layer
O: maxillary process of the zygomatic bone
- ant. 2/3 of the zygomatic arch.
I: ramus of mandible (lateral part)
Deep layer
O: medial surface of inferior margin of the zygomatic arch.
I: upper part of the ramus of the mandible.
= Masseteric tuberosity.
N: Masseteric br. of mandibular n.
F: Elevate the mandible
B.S: masseteric art. from maxillary art.
temporal fascia: 2 layers (starts as 1 then continues as 2).
② Temporalis m:
(lies within the temporal fossa of the skull)
O: temporal fossa (up to inf. temporal line)
- temporal fascia.
I: Apex & medial surface of coronoid process of mandible
N: Deep temporal br. of V₃
F: - Ant. fibers → elevates mandible
Post. ll → Retracts mandible
B.S: Deep temporal br. of maxillary art.
- Middle 〃 of superficial temporal art.
zygomatic arch!
③ Medial pterygoid m.:
(quadrangular m. situated in the infratemporal fossa).
Deep head
O: medial surface of the lateral pterygoid plate of the sphenoid bone
Superficial head
O: tuberosity of the maxilla
I: medial surface of the mandibular ramus close to the angle of the mandible.
N: medial pterygoid br.
F: elevation of the mandible
- Side-to-side movements
B.S: Pterygoid br. of the maxillary art.
④ Lateral Pterygoid m.:
(triangular m. lies in the infratemporal fossa)
Superior head (smaller)
O: roof of infratemporal fossa of sphenoid bone.
Inferior head (larger)
O: lateral surface of lateral Pterygoid plate of sphenoid bone.
shallow depression at the
I: Anterior aspect of the neck of the mandible called (Pterygoid fovea)
N: Lateral pterygoid br.
F: movement of the mandible
B.S: pterygoid br. of maxillary art.
4 sides of the mandible