Question

Which of the following cranial nerve is instrumental in motor function:

• A. Vestibulocochlear
• B. Olfactory
• C. Accessory
• D. Optic

Answer 1

The Correct Option is C

The correct option is (C): Accessory.

Answer 2

The question asks which of the listed cranial nerves is primarily involved in motor function. Let's check each one.

1. Vestibulocochlear: This is cranial nerve VIII, a purely sensory nerve that carries information about hearing and balance from the inner ear to the brain. It carries no motor fibers.
2. Olfactory: This is cranial nerve I, a purely sensory nerve responsible for the sense of smell. It has no motor function.
3. Accessory: This is cranial nerve XI, and it is a purely motor nerve. It supplies the sternocleidomastoid and trapezius muscles, controlling head rotation, neck movement, and shoulder shrugging. Since its entire function is motor, this fits the question directly.
4. Optic: This is cranial nerve II, a purely sensory nerve that carries visual information from the retina to the brain. It has no motor role.

Of the four cranial nerves listed, three (olfactory, optic, and vestibulocochlear) are purely sensory, while the accessory nerve is purely motor, making it the one instrumental in motor function.

Therefore, the correct answer is Accessory.