The temporalis muscle is a large, flat muscle located in the temporal region of the head. It is one of the muscles of mastication (chewing) and is responsible for closing the jaw.
Structure
The temporalis muscle has a broad, fan-shaped origin on the temporal bone of the skull, specifically on the temporal fossa and the inferior temporal line. It has a triangular shape with a base at the skull and an apex at the mandible. The muscle fibers converge towards the apex, where they attach to the coronoid process of the mandible via the temporal tendon.
The temporalis muscle is innervated by the mandibular branch of the trigeminal nerve (CN V3). It is supplied by the middle temporal artery, a branch of the external carotid artery.
Location
As its name suggests, the temporalis muscle is located in the temporal region of the head, which is the region above the zygomatic arch and in front of the ear. It is covered by the temporal fascia, a thin layer of connective tissue. The temporalis muscle is superficial to the temporalis fascia, and can be easily palpated when the jaw is clenched.
Function
The primary function of the temporalis muscle is to close the jaw, or bring the mandible towards the skull. This action is called closing or occlusion. The temporalis muscle also aids in the side-to-side movement of the jaw, or lateral excursion. When the jaw is open, the temporalis muscle is relaxed.
The temporalis muscle works in opposition to the masseter and medial pterygoid muscles, which are responsible for opening the jaw. Together, these three muscles of mastication enable the movement of the jaw necessary for chewing and speaking.
Clinical significance
The temporalis muscle may be involved in various clinical conditions, such as temporomandibular joint (TMJ) disorder, bruxism (teeth grinding), and trismus (limited mouth opening). Dysfunction of the temporalis muscle may result in pain and discomfort in the temporal region, and may also lead to difficulties with chewing and speaking.
Temporalis muscle dysfunction may be treated with a combination of physical therapy, medications, and occlusal splints. In severe cases, surgical intervention may be necessary. It is important to address temporalis muscle dysfunction early on to prevent further complications and to maintain proper jaw function.
