Which nerve is the major motor nerve to the muscles of facial expression?

• A. CN VII
• B. CN V
• C. CN IX
• D. CN X

Answer: (A)

Movements of facial expression are controlled by the facial nerve. This nerve provides the motor innervation to all the muscles derived for facial expression, including the frontalis, orbicularis oculi, zygomaticus, buccinator, and orbicularis oris. It travels from the brainstem through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen before giving branches to these muscles. The trigeminal nerve handles facial sensation and the muscles of mastication, while glossopharyngeal and vagus nerves serve other functions in the throat and autonomic regions. So the major motor nerve to the muscles of facial expression is the facial nerve.