The masseter is the main muscle that moves your jaw. It originates on the zygomatic arch and maxilla, and inserts on the coronoid process and Ramus of the mandible. It’s actions are to elevate the mandible and close the jaw. The deep fibres of this muscle also retrude the mandible. This muscle commonly harbours trigger points as a result of teeth grinding. Trigger points in this muscle are often also associated with tmj dysfunction. Trigger points in the upper part of this muscle will refer pain to the upper molars and maxilla often felt as sinusitis. Trigger points in the lower portion of this muscle refer to the lower molars and temple. All trigger points can cause tooth sensitivity