Also known as the temporal muscle, the temporalis is the largest of the four muscles of mastication (chewing). It lies on the lateral aspect of head and upper portion of face. Being fan-like in shape, it is very wide and flat in its upper portion and narrow in its lower part.
The temporalis muscle arises from the temporal surface of the greater wing of sphenoid bone and the squamous part of temporal bone. Then this broad muscle of mastication extends downwards, covering the fossa temporalis, as it tapers into a flat and narrow bundle of muscle fibers which converge to form a strong tendon. This tendon runs down medially extending behind the zygomatic arch to get inserted into the coronoid process of mandible (lower jaw).
Action/Function
Upon contraction, the temporal muscle raises the lower mandible, with its posterior fibers pulling it backwards and upwards. It assists the masseter in the function of mastication.
Innervation
The temporalis muscle is innervated by the deep temporal nerves, which are efferent nerve fibers originating from the trigeminal cranial nerve (CN V).
Blood Supply
This broad muscle receives oxygenated blood from the the deep temporal and superficial temporal artery, which are branches of the maxillary and the external carotid artery respectively.
Below, schematic drawing which exhibits the muscle of mastication, including the temporalis.
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