Question

Which cranial nerve innervates the medial rectus muscle?

1) CN I (olfactory)
2) CN II (optic)
3) CN III (oculomotor)
4) CN IV (trochlear)
5) CN V (trigeminal)

Answer 1

The medial rectus muscle is innervated by the oculomotor nerve (CN III), which controls the majority of eye movements, upper eyelid elevation, and pupillary constriction.

Step-by-step explanation:

The cranial nerve that innervates the medial rectus muscle, which is responsible for adducting the eye, is the oculomotor nerve (CN III). This is one of the three cranial nerves involved in eye movement, with the others being the trochlear nerve (CN IV) for the superior oblique muscle and the abducens nerve (CN VI) for the lateral rectus muscle. The oculomotor nerve arises from the midbrain and controls most of the eye's movements along with upper eyelid elevation and pupillary constriction.