Which muscle is primarily responsible for adducting the eye?

The medial rectus muscle is the primary muscle responsible for adducting the eye, which means it helps to move the eye towards the nose. This action is essential for coordinating binocular vision and allowing both eyes to focus on a close object. The medial rectus is one of the extraocular muscles that control eye movement and is innervated by the oculomotor nerve (cranial nerve III).

In the context of eye movements, the other muscles listed perform different functions. The lateral rectus muscle abducts the eye, moving it away from the midline. The superior rectus muscle primarily elevates the eye and contributes to adduction, but is not primarily responsible for it. Similarly, the inferior rectus muscle mainly depresses the eye, with some contribution to adduction as well. However, the clear primary role in adduction is held by the medial rectus muscle.