The temporalis muscle is one of the four major muscles of mastication (chewing) and represents a significant portion of the muscle mass on the side of the head. This large, fan-shaped muscle is fundamental to oral function, playing a role in actions like talking, swallowing, and biting. As a primary mover of the lower jaw, it is a frequent contributor to common types of head and face discomfort.
Where the Temporalis Muscle is Located
The temporalis muscle is a broad, flat structure situated on the side of the skull, completely filling the large depression known as the temporal fossa. Its fan-like shape spreads widely across the temporal, frontal, and parietal bones of the skull, forming the muscle’s origin.
From this wide origin, the muscle fibers converge downward, passing underneath the zygomatic arch (cheekbone). The muscle narrows into a thick tendon that inserts onto the coronoid process of the mandible, a bony projection on the lower jaw. This arrangement connects the skull to the lower jawbone, providing leverage for movement. The temporalis muscle receives its signal to contract from the deep temporal nerves, which are branches of the mandibular division of the Trigeminal Nerve (Cranial Nerve V3).
How the Temporalis Muscle Moves the Jaw
The primary action of the temporalis muscle is to close the jaw, a movement known as elevation. Contraction pulls the mandible upward, bringing the upper and lower teeth together with force necessary for crushing food during chewing. This action makes the temporalis one of the strongest muscles controlling the temporomandibular joint.
The fan-like structure allows for a secondary movement. The anterior fibers run vertically and are primarily responsible for elevation. The posterior fibers run more horizontally, and when they contract, they pull the mandible backward, a movement called retraction. Retraction allows the chin to be pulled back after the jaw has been extended forward.
Common Sources of Temporalis Muscle Pain
The temporalis muscle is a frequent source of head and facial pain due to its role in mastication and connection to the skull. Overuse from habitual teeth clenching or grinding (bruxism) is a common cause of inflammation and soreness. This repetitive strain can lead to the development of painful, hyper-irritable spots within the muscle tissue known as myofascial trigger points.
Referred Pain
When active, these trigger points cause referred pain, meaning the discomfort is felt in areas distant from the muscle. Temporalis trigger points often refer pain across the temple and side of the head, sometimes radiating behind the eye, which can mimic the symptoms of a tension headache or migraine. Referred pain may also be felt in the upper teeth, resembling a toothache even without a dental issue.
Temporomandibular Joint Disorders (TMD)
The temporalis muscle is involved in Temporomandibular Joint Disorders (TMD), a group of conditions affecting the jaw joint and surrounding musculature. Chronic stress often causes people to unconsciously clench their jaws, putting excessive load on the temporalis. Additionally, prolonged activities that force the jaw open, such as extended dental procedures, can strain the muscle and its tendon, leading to local tenderness and restricted movement.