optic nerve (CN II, ON)

Introduction

Special sensory afferent fibers relay visual stimuli.

Origin

retinal ganglion cells

Afferents

• lateral geniculate nucleus in the thalamus
• superior colliculus
• pretectum

Course

• it exits the cranium through the optic canal.
• optic fibers temporal to the fovea connect with the brain ipsilaterally
• fibers nasal to the fovea cross over to the contralateral side at the optic chiasm

Notes

• although classified as a cranial nerve, it is actually an extension of the forebrain

More general terms

• cranial nerve

More specific terms

• outer/dural/external sheath of optic nerve

Additional terms

• optic nerve pallor