The temporalis muscle, a broad, fan-shaped muscle, is situated on each side of the head, occupying the temporal fossa. This muscle extends from the side of the skull down to the lower jaw, known as the mandible. As one of the primary muscles involved in mastication, or chewing, the temporalis muscle plays a significant role in enabling jaw movements. Its position and structure enable various fundamental oral functions.
Primary Jaw Elevation
The primary action of the temporalis muscle is the elevation of the mandible, closing the mouth. The anterior fibers of this muscle, which run in a nearly vertical direction, are effective at pulling the jaw upwards. When these fibers contract, they exert a strong upward force on the lower jaw, allowing for powerful biting. This action is fundamental for breaking down food and plays a continuous role in maintaining jaw closure.
Jaw Retraction
Beyond closing the mouth, the temporalis muscle also performs jaw retraction. The posterior fibers of the muscle, oriented more horizontally, are primarily responsible for this movement. This backward movement of the jaw is important for precise teeth alignment and for positioning the jaw during oral activities. Retraction contributes to the controlled, coordinated movements required for efficient chewing and swallowing.
Coordinated Chewing
The temporalis muscle’s actions of elevation and retraction are integral to chewing, working with other mastication muscles. During chewing, the temporalis muscle contributes to the rhythmic opening and closing of the mouth, providing power for biting and precision for grinding. Its ability to elevate the jaw ensures the force needed to crush food, while its retraction capability helps position the jaw for side-to-side grinding motions. The coordinated activity of the temporalis muscle, alongside others, facilitates efficient food breakdown.
Impact of Dysfunction
When the temporalis muscle does not function optimally, it can lead to issues affecting jaw movement and comfort. Individuals may experience pain in the temporal area, manifesting as headaches or facial pain that sometimes radiates to the teeth. Impaired function can also result in difficulty chewing and a limited range of jaw movement, sometimes described as a restricted opening. Habits such as jaw clenching or teeth grinding can overwork the temporalis muscle, leading to muscle fatigue and discomfort. These symptoms relate to the muscle’s reduced ability to perform its normal elevating and retracting actions effectively.