masseter

Masseter
Muscles of the head and neck.
Dissection, showing salivary glands of right side. (Masseter visible at center.)
Latin	musculus masseter
Gray's	subject #109 385
Origin	zygomatic arch and maxilla
Insertion	coronoid process and ramus of mandible
Artery	masseteric artery
Nerve	mandibular nerve (V3)
Actions	elevation (as in closing of the mouth) and retraction of mandible
Antagonist	Platysma 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.

Origin and insertion of the two heads

The masseter is a thick, somewhat quadrilateral muscle, consisting of two portions, superficial and deep.

The fibers of the two portions are continuous at their insertion. The masseter muscle is sometimes the target of plastic jaw reduction surgery.

Superficial

The superficial portion, the larger, arises by a thick, tendinous aponeurosis from the zygomatic process of the maxilla, and from the anterior two-thirds of the lower border of the zygomatic arch.

Its fibers pass downward and backward, to be inserted into the angle and lower half of the lateral surface of the ramus mandible.

Deep

The deep portion 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 and the lateral surface of the coronoid process of the mandible.

The deep portion of the muscle is partly concealed, in front, by the superficial portion; behind, it is covered by the parotid gland.

Innervation

Along with the other three muscles of mastication (temporalis, medial pterygoid and lateral pterygoid), the masseter is innervated by the mandibular division of the trigeminal nerve.

Additional images

Left temporal bone. Outer surface.	Left temporal bone. Inferior surface.	Left zygomatic bone. Temporal surface.	Mandible. Outer surface. Side view.
Base of skull. Inferior surface.	The arteries of the face and scalp.	Veins of the head and neck.	Mandibular division of the trifacial nerve.
Muscles of the head, face, and neck.

External links

• LUC mass
• -100270003 at GPnotebook
• Masseter+muscle at eMedicine Dictionary

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