Optic Nerve
| Definition: |
The 2nd cranial nerve. The optic nerve conveys visual information from the retina to the brain. The nerve carries the axons of the retinal ganglion cells which sort at the optic chiasm and continue via the optic tracts to the brain. The largest projection is to the lateral geniculate nuclei; other important targets include the superior colliculi and the suprachiasmatic nuclei. Though known as the second cranial nerve, it is considered part of the central nervous system. |
| Notes: |
2d cranial nerve; neopl = OPTIC NERVE NEOPLASMS (IM) + histol type of neopl (IM); atrophy = OPTIC ATROPHY; neuritis = OPTIC NEURITIS; optic nerve head = OPTIC DISK |
Optic Nerve Categories.
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Optic Chiasm - The X-shaped structure formed by the meeting of the two optic nerves. At the optic chiasm the fibers from the medial part of each retina cross to project to the other side of the brain while the lateral retinal fibers continue on the same side. As a result each half of the brain receives information about the contralateral visual field from both eyes. |
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Optic Disk - The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve. |
Optic Nerve Definitions and Terms
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