Which statement about jaw muscles is true?

• A. They are only located on the face and head.
• B. They include muscles that move the jaw.
• C. They do not contribute to chewing.
• D. They are controlled by the spinal cord only.

Answer: (B)

Jaw muscles move the jaw to bite, chew, and speak. The main muscles that do this—the masseter, temporalis, and the medial and lateral pterygoids—produce up-and-down as well as side-to-side jaw movements, which are essential for grinding food and coordinating chewing. This control comes from cranial nerves, specifically the trigeminal nerve, with motor signals originating in the brainstem and cortex, not from the spinal cord. So, the statement that jaw muscles include muscles that move the jaw best captures their essential role. The other options conflict with how these muscles function (they do contribute to chewing) and with how they’re controlled (cranial, not spinal nerves).