The 2nd cranial nerve; the nerve of vision. The 2 optic nerves each consist of about 1 million nerve fibres that transmit impulses from the retina to the brain. The optic nerves converge behind the eyes, where fibres from the inner halves of the retina cross over. Nerve fibres from the right halves of both retinas go to right side of the occipital lobes in the brain; those from the left halves go to the left side. Disorders of the optic nerve include optic neuritis and papilloedema. The latter is caused by pressure on the nerve from disease in the orbit or a brain tumour.
Optic nerve |
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