Trigeminal motor nucleus corresponds to which cranial nerve?

• A. II
• B. III
• C. V
• D. VII

Answer: (C)

The trigeminal motor nucleus is the motor component of the trigeminal nerve, cranial nerve V. Located in the pons, it sends efferent fibers to muscles derived from the first pharyngeal arch, mainly the muscles of mastication—masseter, temporalis, and the medial and lateral pterygoids—as well as the tensor tympani, tensor veli palatini, and, via the mylohyoid and anterior belly of the digastric, some other functions. These motor fibers travel with the mandibular division (V3) of the trigeminal nerve to reach their targets. Because of this motor association, the trigeminal motor nucleus corresponds to cranial nerve V. Other nerves listed are involved in different functions (for example, the optic nerve handles vision, the oculomotor nerve controls most eye movements and pupil constriction, and the facial nerve governs facial expression).