Masseter 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.

Structure

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. Discovered in 1957

Superficial head

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.

Deep head

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.