What muscles are used to close the jaw?

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

Answer: (A)

Closing the jaw involves lifting the lower jaw up to bring the teeth together. The main muscles that do this are the masseter and the temporalis. The masseter runs from the cheekbone to the lower jaw and acts as a powerful elevator, pushing the mandible upward. The temporalis sits on the side of the skull and, through its vertical fibers, elevates the mandible as well, with the ability to add a slight backward pull when needed. Together, they provide the strongest and most reliable jaw-closing action.

Other muscles can influence jaw movement, but they either open the jaw or assist in closing in a secondary way. The lateral pterygoid mainly opens and protrudes the jaw, while the digastric opens the jaw. The medial (internal) pterygoid does assist with closure, but the combination of the masseter and temporalis best represents the primary closing pair.