Which nerve in the pons is involved in facial expression, saliva and tear production, and taste from the anterior two-thirds of the tongue?

• A. Vestibulocochlear (CN VIII)
• B. Facial (CN VII)
• C. Glossopharyngeal (IX)
• D. Vagus (X)

Answer: (B)

The facial nerve is involved here. It originates in the pons and is a mixed cranial nerve that handles several related roles: motor control of the muscles used for facial expression, parasympathetic fibers that stimulate tear production from the lacrimal glands and saliva from the submandibular and sublingual glands, and special sensory fibers for taste from the anterior two-thirds of the tongue (via the chorda tympani). The other nerves have different primary functions—vestibulocochlear handles hearing and balance; glossopharyngeal handles taste from the posterior tongue and some salivary functions; vagus handles widely distributed autonomic control and sensation in the thorax and abdomen—so they don’t match all three functions described.