Optic nerve (intraorbital part)
Nervus opticus (pars orbitalis)
Sensory (eye & ear)NervesHeadLeft and right
View left in 3D View right in 3D
- What it is
- Cranial nerve II, a bundle of about 1.2 million retinal ganglion-cell axons. Its orbital part runs in a gentle S-curve from the back of the eyeball to the optic canal at the orbit apex; beyond the apex it continues to the optic chiasm.
- Function
- Carries visual information from the retina to the brain.
- Size
- Orbital part ~25 mm long (slack allows eye movement), 3-4 mm thick; whole nerve ~45-50 mm.
- Clinical note
- It is a tract of the central nervous system, so it does not regenerate; inflammation (optic neuritis) is often the first sign of multiple sclerosis.