The optic nerve
Optic nerve (II) · nervus opticus
The cable that carries everything you see from the eye to the brain.
What it does
Each optic nerve carries about a million nerve fibres from the retina at the back of the eye to the brain. Behind the eyes the two nerves meet in an X-shaped crossing, where fibres from the inner half of each retina swap sides, so each half of the brain sees one side of the world.
Surprising fact
Where the optic nerve leaves the eye there are no light sensors, giving every eye a blind spot, which your brain fills in so smoothly you never notice it.
Why it matters
Glaucoma slowly damages the optic nerve, often without symptoms at first, which is why regular eye pressure checks matter as you get older.
Nearby
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Sources
Drafted with AI help; awaiting a human fact-check against these sources.
Open in the 3D atlas · Suggest a correction · Not medical advice.
3D models: Z-Anatomy & BodyParts3D (CC BY-SA 4.0 / 2.1 JP). Card text CC BY 4.0.