Hello again! This is Matt from Kenhub, and in this tutorial, we will discuss the function and anatomy of the temporalis muscle.
The temporal muscle, also known as the temporalis, is a flat, fan-shaped muscle of mastication on the lateral side of the skull. It arises from the temporal fossa, a large depression on the side of the skull and the temporal fascia, which completely covers the surface of muscle.
From there, the muscle descends through the gap between the zygomatic arch and the skull, forms a thick tendon, and inserts at the coronoid process of the mandible.
The temporalis is innervated by the deep temporal nerves branching off from the mandibular nerve. You can see the mandibular nerve, highlighted in green, on the image on your screen.
Functionally, the muscle can be divided into two parts. The anterior part runs almost vertically and moves the mandible forward, which is known as protrusion. In contrast, the fibers of the posterior part course almost horizontally and pull the mandible backwards, which is known as retrusion.
The activation of the entire muscle moves the mandible dorsocranially, leading to a strong jaw closure known as elevation.
Due to its size, it can be palpated without difficulty, especially when the mouth is opened and closed. The temporal is the most powerful muscle of the temporomandibular joint.