Which muscle pair is primarily responsible for jaw closure?

• A. Masseter and temporalis
• B. Masseter and digastric
• C. Temporalis and pterygoid
• D. Masseter and lateral pterygoid

Answer: (A)

Closing the jaw is accomplished mainly by the muscles that lift the mandible against the upper teeth. The strongest elevators are the masseter and the temporalis. The masseter, attaching from the cheekbone to the lower jaw, generates powerful upward force to raise the mandible for biting. The temporalis sits along the side of the skull and elevates the mandible, helping to close the mouth and also assisting with backward movement of the jaw. Together, they provide the primary closing action.

Other muscles in the list do not fit the role as closely. The digastric opens the jaw rather than closes it. The lateral pterygoid helps with opening and guiding movement, while the medial pterygoid does contribute to elevation but is not the main pair responsible for closing—its action is more about working with the other elevators during grinding and chewing.