The masseter muscle is the strongest and the main muscle of mastication (chewing). It arises from the inferior half of the zygomatic arch (cheek bone) by a superficial and a deep portion. The superficial portion of the masseter originates as tendinous fibers from the anterior and middle part of the zygomatic arch. The deep portion, on the other hand, arises as a muscle from the middle and posterior areas of the zygomatic arch.
The bands of muscle fibers of the masseter superficial portion runs downwards and backwards, in an oblique fashion. Those of the deep portion, however, descends downwards and slightly forwards. Both portions of the masseter get together before being inserted into the external surface of the ramus of the mandible and its angle in the region of the masseteric tuberosity.
Action/Function
The masseter raises the lower jaw during mastication, with its superficial portion assisting in the forward protrusion of mandible.
Innervation
This strong muscle of mastication is innervated by the branches from the trigeminal nerve (CN V).
Blood Supply
The masseter receives oxygen-rich blood from the masseteric artery, which springs from the second portion of the maxillary artery.
Below, two drawings of human skull, showing the two portions of masseter muscle.
