Which muscle retracts the mandible?

• A. Masseter
• B. Medial pterygoid
• C. Temporalis
• D. Lateral pterygoid

Answer: (C)

Retracting the mandible is accomplished mainly by the temporalis, especially its posterior fibers. The temporalis originates from the temporal fossa and inserts on the coronoid process of the mandible. When the posterior portion contracts, it pulls the mandible backward, producing retraction, particularly when the mouth is closed. The anterior fibers of the temporalis instead elevate the mandible to close the jaw. Other muscles have different primary actions: the masseter primarily elevates the jaw (and can assist with some protrusion), the medial pterygoid elevates and helps with grinding, and the lateral pterygoid opens the mouth and protrudes the mandible. Thus, the temporalis is the muscle most responsible for retracting the mandible.