Optic Nerve

Structure

The optic nerve is technically a tract of the central nervous system, not a true peripheral nerve. It contains roughly one million axons of retinal ganglion cells, sheathed in myelin made by oligodendrocytes.

Function

Signals from the temporal half of each retina stay on the same side, while signals from the nasal halves cross at the optic chiasm, allowing the brain to compare input from both eyes.

Clinical note

Diseases such as glaucoma, optic neuritis, and elevated intracranial pressure can damage the nerve and cause vision loss.