Which nerve stimulates the muscles used for facial expression?

• A. Facial nerve
• B. Trigeminal nerve
• C. Accessory nerve
• D. Glossopharyngeal nerve

Answer: (A)

Muscles of facial expression are innervated by the facial nerve (cranial nerve VII). It provides motor fibers to all the facial expression muscles, which originate from the second pharyngeal arch. After its nucleus in the pons, it travels through the temporal bone and exits the skull at the stylomastoid foramen before branching to move the face. The other nerves have different roles: the trigeminal nerve mainly handles sensation of the face and muscles of mastication; the accessory nerve supplies the sternocleidomastoid and trapezius; the glossopharyngeal nerve serves the stylopharyngeus and provides taste to the posterior tongue with parasympathetic fibers to some salivary glands. Therefore, the nerve that stimulates the muscles used for facial expression is the facial nerve.