Which cranial nerve is tested for eye muscles and pupil response?

The oculomotor nerve is primarily responsible for controlling most of the eye muscles, which are essential for moving the eye in various directions. This cranial nerve also plays a crucial role in adjusting the size of the pupil in response to light and controlling the shape of the lens for accommodation when focusing on objects at different distances. Therefore, testing the oculomotor nerve effectively assesses both eye muscle function and pupil response, making it the correct choice for this question.

The optic nerve is mainly involved in vision, transmitting visual information from the retina to the brain, but it does not control eye movement or pupil response. The facial nerve is responsible for facial expressions and some functions of taste but does not relate to eye muscles or pupil response. The trigeminal nerve primarily handles sensation in the face and motor functions like biting and chewing, not eye movements or pupil reflexes. Thus, the emphasis on eye muscles and pupil response distinctly aligns with the function of the oculomotor nerve.