Which nerve is not involved in controlling facial movements?

Which nerve is not involved in controlling facial movements?

• A. Facial (VII)
• B. Trigeminal (V)
• C. Spinal Accessory (XI)
• D. Hypoglossal (XII)

Answer: (C)

The spinal accessory nerve (XI) primarily innervates the sternocleidomastoid and trapezius muscles, which are responsible for movements of the head, neck, and shoulders. It does not play a role in controlling facial movements, which involve the muscles responsible for expressions and other intricate movements of the face.

In contrast, the facial nerve (VII) is directly responsible for the majority of the muscles of facial expression. The trigeminal nerve (V) has a role in sensation in the face and also contributes to the muscle control needed for chewing, but it is not primarily responsible for facial expressions themselves. The hypoglossal nerve (XII) is involved in controlling the tongue's movements, which can affect facial expressions indirectly but is not a facial nerve.

Thus, the spinal accessory nerve is not part of the circuitry that controls facial movements, making it the correct answer.