The oculomotor nerve is the third of 12 pairs of cranial nerves in the brain. This nerve is responsible for eyeball and eyelid movement. This nerve follows the olfactory and optic nerves, in addition to the preceding trochlear, trigeminal, abducens, facial, vestibulocochlear, ghlossopharyngeal, vagus, accessory, and hypoglossal nerves. This nerve involves two separate components, each of which has a distinct function. The somantic motor component supplies four extraocular muscles in the eye and the upper eyelid's levator palpebrae superioris with motor fibers. It controls the muscles that allow for visual tracking and fixation by the eye. The visceral motor component controls parasympathetic innervation of the ciliary muscles and constrictor papillae, aiding in accommodation and papillary light reflexes. This nerve can become paralyzed in a condition known as oculomotor nerve palsy. This condition can result from multiple sclerosis or other demyelinating diseases, direct trauma, uncal herniation or increased intercranial pressure, space-occupying lesions such as brain cancer, microvascular disease such as diabetes, or spontaneous subarachnoid hemorrhage such as a berry aneurysm. The oculomotor nerve is responsible for most eye and eyelid movements, though the trochlear nerve and abducens nerve also contribute to eye movement.
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In Depth: Oculomotor nerve