Basilar artery (BA)

Extends anterior to the pons behind the clivus. Bifurcates into the PCAs in the interpeduncular or suprasellar cistern at or above the dorsum sellae.

1. Median/paramedian perforators
   • Small branches arising from the posterior surface of the BA. Most enter the pons.
   • Supply:
     • Median-paramedian and to a lesser degree, lateral pons

2. Short circumferential arteries
   • Short branches that perforate more laterally.
   • Supply:
     • Lateral basis pontis
     • Part of pontine tegmentum
     • Parts of middle cerebellar peduncle
     • Lateral aspect of superior medulla

3. Anterior inferior cerebellar artery (AICA)
   • Arises from the first or second third of the BA. Runs laterally toward the inferior part of the pons and divides into a rostrolateral and caudomedial branches. The rostrolateral branch gives off the labyrinthine artery.
   • Supplies:
     • Lateral part of pons
     • Middle cerebellar peduncle
     • Lateral aspect of superior medulla
     • Flocculus
     • The labyrinthine artery supplies the labyrinth and may supply the intrameatal parts of cranial nerves VII and VIII
     • The labyrinthine artery may uncommonly arise from the basilar artery

4. Superior cerebellar artery (SCA)
   • Arises from the second third of the BA and rarely from the PCA. Divides into superior and inferior branches. Gives off small branches to the superior posterior pons and midbrain, and branches to the cerebellar hemisphere.
   • Supplies:
     • Upper posterior pons and midbrain
     • Superior vermis
     • Superior parts of the cerebellar hemisphere