Optic nerve (CN II), intracranial part

Nervus opticus (pars intracranialis)

NervousNervesHeadLeft and right

View left in 3D View right in 3D

What it is
The intracanalicular and intracranial part of the optic nerve, from the apex of the orbit through the optic canal to the optic chiasm. The part inside the orbit is built with the eye. It is really a tract of the brain, wrapped in all three meninges.
Function
Carries about 1.2 million retinal ganglion-cell axons - the entire visual signal of one eye - toward the chiasm.
Size
4 mm in diameter with its sheath; intracranial part ~10 mm, canal ~6 mm
Clinical note
Because it is bathed in cerebrospinal fluid, raised intracranial pressure swells the nerve head (papilloedema), visible with an ophthalmoscope.

Part of Optic chiasm

Nearby nervous structures Abducens nerve (CN VI), Amygdala, Oculomotor nerve (CN III), Oculomotor nerve root (CN III), Olfactory nerve (CN I), Olfactory tract root (CN I), Optic tract, Optic tract root (CN II), Trigeminal ganglion, Trochlear nerve (CN IV)