Optic nerve
Extension of the brain - surrounded by cranial meninges + subarachnoid space
Innervations
Extracranial component -
Intracranial component - Visual pathways
Arterial supply
- Ophthalmic artery (?)
Venous drainage
- supraorbital + angular vein → superior ophthalmic vein → [sup orbital fissure] → cavernous sinus
- inferior ophthalmic vein
- → [sup orbital fissure] → cavernous sinus
- → cavernous sinus
- → [inferior orbital fissure] → pterygoid plexus
⚠️ infection can spread this way
with Raised ICP:
- raised pressure in subarachnoid space
- impaired venous drainage along retinal veins → oedema of optic disc