Which nerve is primarily responsible for sensation of the face and motor functions for mastication?

• A. Trigeminal (CN V)
• B. Vestibulocochlear (CN VIII)
• C. Facial (CN VII)
• D. Accessory (XI)

Answer: (B)

The sensation of the face and the ability to chew are carried by the trigeminal nerve. This nerve (cranial nerve V) has three divisions: the first two are purely sensory and supply sensation to different facial regions, while the third division provides both sensory input from the lower face and motor output to the muscles used in mastication (masseter, temporalis, and the pterygoids). The other nerves do not handle both of these roles: the vestibulocochlear nerve handles hearing and balance, the facial nerve mainly controls facial expressions and taste, and the accessory nerve innervates neck muscles. So the trigeminal nerve best fits the described functions.