Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Oculomotor nerve
Medically reviewed by Min Clinic Staff | Updated: January 2026
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. Paralysis of the oculomotor nerve results in a drooping eyelid (ptosis), deviation of the eyeball outward (and therefore double vision), and a dilated (wide-open) pupil.