oculomotor nerve definition
Oculomotor nerve: The third cranial nerve. The oculomotor nerve is responsible for the nerve supply to muscles around the eye, including the upper eyelid muscle, which raises the eyelid; the extraocular muscle, which moves the eye inward; and the pupillary muscle, which constricts the pupil.culomotor nerve: The third cranial nerve. The oculomotor nerve is responsible for the nerve supply to muscles around the eye, including the upper eyelid muscle, which raises the eyelid; the extraocular muscle, which moves the eye inward; and the pupillary muscle, which constricts the pupil.