The masseter muscle is one of the primary muscles involved in the movement of the jaw. It is a powerful muscle responsible for closing the jaw during activities like chewing and clenching. The masseter muscle is located in the jaw area and is often considered one of the major muscles of mastication (chewing).

The masseter muscles have become of interest in certain cosmetic and therapeutic procedures. For example, shots of neuromodulators like intradermal shots can be used to temporarily relax the masseter muscles. This is sometimes done for cosmetic purposes, such as jawline contouring, or to address conditions like bruxism (teeth grinding) and temporomandibular joint disorders (TMJ).