Definition of Oculomotor nerve

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.


Last Editorial Review: 3/19/2012

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