Masseter muscle

Masseter
The left masseter muscle (red highlight), shown partially covered by superficial muscles such as the platysma muscle, the zygomaticus major muscle and the zygomaticus minor muscle.
Details
Origin	zygomatic arch and maxilla
Insertion	coronoid process, ramus of mandible, cementomaxillary tendon and cementomandibular tendon
Artery	masseteric artery
Nerve	mandibular nerve (V3)
Actions	elevation (as in closing of the mouth) and protraction of mandible
Identifiers
Latin	musculas masseter
TA	A04.1.04.002
FMA	48996
Anatomical terms of muscle []

In human anatomy, the masseter is one of the muscles of mastication. In the animal kingdom, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the most superficial and one of the strongest. The masseter muscle is also known as the 'thinker' because of how people sometimes rest their hand on it, when they are in deep concentration.

The masseter is a thick, somewhat quadrilateral muscle, consisting of two heads, superficial and deep. The fibers of the two heads are continuous at their insertion.

The superficial head, the larger, arises by a thick, tendinous aponeurosis from the maxillary process of the zygomatic bone, and from the anterior two-thirds of the inferior border of the zygomatic arch. Its fibers pass inferior and posterior, to be inserted into the angle of the mandible and inferior half of the lateral surface of the ramus of the mandible.

The deep head is much smaller, and more muscular in texture. It arises from the posterior third of the lower border and from the whole of the medial surface of the zygomatic arch. Its fibers pass downward and forward, to be inserted into the upper half of the ramus as high as the coronoid process of the mandible. The deep head of the muscle is partly concealed, anteriorly, by the superficial portion. Posteriorly, it is covered by the parotid gland.

Along with the other three muscles of mastication (temporalis, medial pterygoid, and lateral pterygoid), the masseter is innervated by the anterior division of the mandibular division (V3) of the trigeminal nerve. The innervation pathway is: gyrus precentralis > genu capsula interna > nucleus motorius nervi trigemini > nervus trigeminus > nervus mandibularis > musculus masseter.