Which cranial nerve primarily controls ocular movements?

The cranial nerve that primarily controls ocular movements is cranial nerve III, known as the oculomotor nerve. This nerve is responsible for the majority of eye movements, including the movement of the eyelid and the constriction of the pupil. It innervates four of the six extraocular muscles, which allow for precise movements of the eyes in various directions.

Cranial nerve II, or the optic nerve, is primarily responsible for vision but does not control any eye movements. Cranial nerve IV, known as the trochlear nerve, controls only the superior oblique muscle, which is responsible for downward and lateral eye movement. Cranial nerve VI, the abducens nerve, controls the lateral rectus muscle, which is involved in moving the eye laterally but does not assist with the comprehensive range of movements that cranial nerve III facilitates.

Thus, the oculomotor nerve stands out as the primary nerve controlling ocular movements due to its extensive role in innervating multiple eye muscles.