Which nerve innervates most of the extraocular muscles, including eyelid elevation and pupil constriction?

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

Answer: (A)

The nerve that does this is the oculomotor nerve. It supplies most of the extraocular muscles—specifically the medial, superior, and inferior rectus muscles and the inferior oblique—as well as the levator palpebrae superioris, which lifts the upper eyelid. In addition, it carries parasympathetic fibers that reach the pupil via the ciliary ganglion to constrict the pupil (sphincter pupillae) and to adjust the lens (ciliary muscle). That combination—controlling most eye movements, eyelid elevation, and pupil constriction—fits exactly what’s described. The other nerves either control only single eye muscles or mainly serve sensory and other functions, so they don’t match this pattern.