Which cranial nerve is named the oculomotor nerve and controls eye movement and pupil constriction?

• A. Abducens nerve (CN VI)
• B. Trochlear nerve (CN IV)
• C. Trigeminal nerve (CN V)
• D. Oculomotor nerve (CN III)

Answer: (D)

The name oculomotor reflects its main job: moving the eye. This nerve provides motor fibers to most of the extraocular muscles that position the eyeball, and it also innervates the levator palpebrae superioris to lift the eyelid. In addition, it carries parasympathetic fibers that constrict the pupil by activating the sphincter pupillae and adjust the lens for near vision via the ciliary muscle. So it’s the nerve that handles both eye movements and pupil constriction.

Other nerves listed don’t combine these functions. One mainly drives lateral eye movement, another controls downward and inward movement, and the trigeminal nerve mainly carries facial sensation and muscles for chewing, with no primary role in moving the eye or constricting the pupil.