The temporalis muscle is a large, thin fan-shaped muscle located in the side of the skull above and in front of the ear. It is a muscle of mastication and its role is similar to the masseter, which is to elevate the mandible (lower jaw) and so close the mouth. Although the masseter is the more powerful muscle the temporalis is an important chewing muscle. It starts at the temporal bone of the skull but passes all the way down beneath zygomatic arch (cheek bone), attaching to the mandible, enabling it to assist the masseter in closing the jaw but also to retract the mandible.
Temporalis Origin, Insertion, and Action
Origin: Temporal fossa between inferior temporal line (of parietal bone) and infratemporal crest.
Insertion: Coronoid process of the mandible and anterior ramus of the mandible.
Action: Elevates mandible (closes jaw) and retracts mandible (horizontal fibers of posterior part of muscle).