Cranial Nerves: Which option lists a correct pairing?

Cranial Nerves: Which option lists a correct pairing?

• A. I Olfactory - sensory - smell; II Optic - sensory - vision; III Oculomotor - motor - EOM; IV Trochlear - motor - EOM
• B. I Olfactory - sensory - smell; II Optic - motor - vision; III Oculomotor - motor - EOM; IV Trochlear - motor - EOM
• C. I Olfactory - sensory - smell; II Optic - sensory - vision; III Oculomotor - motor - EOM; IV Trochlear - sensory - eye movements
• D. I Olfactory - sensory - smell; II Optic - sensory - vision; III Oculomotor - sensory - pupil constriction; IV Trochlear - motor - EOM

Answer: (A)

Understanding cranial nerves I–IV involves matching each nerve’s modality (sensory or motor) with its primary function. The olfactory nerve is purely sensory and carries smell. The optic nerve is purely sensory and carries vision. The oculomotor nerve is a motor nerve that supplies most of the extraocular muscles and also carries parasympathetic fibers that control pupil constriction and lens focus. The trochlear nerve is motor to the superior oblique muscle, enabling specific eye movements. So the best pairing is the one that lists I as sensory for smell, II as sensory for vision, III as motor to the extraocular muscles, and IV as motor to the extraocular muscles. The other options misstate the modality or function—for example, claiming the optic nerve is motor, or labeling the trochlear nerve as sensory, or describing pupil constriction as a sensory function of the oculomotor nerve.

Understanding cranial nerves I–IV involves matching each nerve’s modality (sensory or motor) with its primary function. The olfactory nerve is purely sensory and carries smell. The optic nerve is purely sensory and carries vision. The oculomotor nerve is a motor nerve that supplies most of the extraocular muscles and also carries parasympathetic fibers that control pupil constriction and lens focus. The trochlear nerve is motor to the superior oblique muscle, enabling specific eye movements.

So the best pairing is the one that lists I as sensory for smell, II as sensory for vision, III as motor to the extraocular muscles, and IV as motor to the extraocular muscles. The other options misstate the modality or function—for example, claiming the optic nerve is motor, or labeling the trochlear nerve as sensory, or describing pupil constriction as a sensory function of the oculomotor nerve.