Which cranial nerve innervates the muscles of mastication?

Which cranial nerve innervates the muscles of mastication?

• A. CN V3
• B. CN V2
• C. CN VII
• D. CN IX

Answer: (A)

The muscles of mastication are innervated by the mandibular division of the trigeminal nerve, CN V3. This division carries the motor fibers that supply the four chewing muscles (masseter, temporalis, and the two pterygoids). These muscles develop from the first pharyngeal arch, which is why their motor supply comes specifically from the arch-one nerve branch. The maxillary division (V2) provides sensory innervation to the midface, not motor to the chewing muscles. The facial nerve (CN VII) controls muscles of facial expression, not mastication, and the glossopharyngeal nerve (CN IX) serves other functions in the oropharynx and tongue. Therefore, CN V3 best explains the innervation of the muscles used for chewing.

The muscles of mastication are innervated by the mandibular division of the trigeminal nerve, CN V3. This division carries the motor fibers that supply the four chewing muscles (masseter, temporalis, and the two pterygoids). These muscles develop from the first pharyngeal arch, which is why their motor supply comes specifically from the arch-one nerve branch. The maxillary division (V2) provides sensory innervation to the midface, not motor to the chewing muscles. The facial nerve (CN VII) controls muscles of facial expression, not mastication, and the glossopharyngeal nerve (CN IX) serves other functions in the oropharynx and tongue. Therefore, CN V3 best explains the innervation of the muscles used for chewing.