Which cranial nerve is responsible for the motor function of the masseter muscle?

The cranial nerve responsible for the motor function of the masseter muscle is indeed the trigeminal nerve, which is cranial nerve V. The masseter muscle plays a critical role in the process of mastication, or chewing, and is primarily responsible for elevating the mandible (lower jaw) to close the mouth.

The trigeminal nerve has three branches, with the mandibular branch (V3) providing motor innervation to the muscles of mastication, including the masseter. This connection makes the trigeminal nerve essential for the efficient functioning of the jaw during activities like eating and speaking.

Understanding the functional anatomy of cranial nerves is crucial, as it helps in the assessment and treatment of various neurological conditions that may affect chewing and jaw movement.