Which cranial nerve is responsible for lateral eye movement?

The cranial nerve responsible for lateral eye movement is the abducens nerve. This nerve specifically innervates the lateral rectus muscle, which is one of the six extraocular muscles that control eye movement. When the lateral rectus muscle contracts, it allows the eye to move outward, away from the midline of the body, facilitating lateral gaze.

In contrast, the oculomotor nerve controls most of the other extraocular muscles, including those responsible for moving the eye up, down, and medially, as well as controlling the constriction of the pupil and maintaining an open eyelid. The facial nerve, primarily responsible for the muscles of facial expression, does not have a role in eye movement. Meanwhile, the trochlear nerve innervates the superior oblique muscle, which is responsible for downward and lateral movements of the eye, but not specifically lateral movement on its own. Thus, the abducens nerve is uniquely specialized for lateral eye movement, making it the correct choice.