Which cranial nerve is primarily responsible for motor control of the muscles of mastication?

The trigeminal nerve is the cranial nerve responsible for motor control of the muscles involved in mastication, which includes chewing. Specifically, it is the motor component of the mandibular branch (V3) of the trigeminal nerve that innervates the muscles responsible for closing the jaw, such as the masseter and temporalis muscles, as well as the lateral pterygoid muscle for moving the jaw side to side.

While the facial nerve innervates the muscles of facial expression, it does not play a direct role in mastication. The accessory nerve primarily provides motor function to the sternocleidomastoid and trapezius muscles, contributing to shoulder elevation and head rotation, but not to mastication. The hypoglossal nerve controls the movements of the tongue, which is essential for speech and swallowing but does not function in the muscles of mastication. Thus, the trigeminal nerve is uniquely positioned to control the complex movements required for chewing and is the correct answer.