Which cranial nerve provides the afferent limb of the corneal reflex?

Which cranial nerve provides the afferent limb of the corneal reflex?

• A. Cranial Nerve II
• B. Cranial Nerve III
• C. Cranial Nerve V
• D. Cranial Nerve VII

Answer: (C)

The corneal reflex uses the trigeminal nerve as the sensory input. Touch to the cornea activates the ophthalmic division (V1) of the trigeminal nerve, sending signal to the brainstem where it prompts an impulse through interneurons to the facial motor nucleus, triggering the blink via the facial nerve. That makes CN V the afferent limb. The optic nerve would be involved in the pupillary light reflex, not this reflex, and the oculomotor nerve provides motor control for pupil constriction and most eye movements, not the corneal sensory input.

The corneal reflex uses the trigeminal nerve as the sensory input. Touch to the cornea activates the ophthalmic division (V1) of the trigeminal nerve, sending signal to the brainstem where it prompts an impulse through interneurons to the facial motor nucleus, triggering the blink via the facial nerve. That makes CN V the afferent limb. The optic nerve would be involved in the pupillary light reflex, not this reflex, and the oculomotor nerve provides motor control for pupil constriction and most eye movements, not the corneal sensory input.