Definition of Third cranial nerve
Third cranial nerve:
Nerve, third cranial: The third cranial nerve is the oculomotor nerve. The cranial nerves emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column. There are twelve cranial nerves.
The oculomotor nerve is responsible for the nerve supply to muscles about the eye:
Paralysis of the oculomotor nerve results in drooping eyelid (ptosis), deviation of the eyeball outward (and therefore double vision) and a dilated (wide-open) pupil.
Last Editorial Review: 6/14/2012
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