Connection lost. Please refresh the page.
Get help How to study Login Register
Ready to learn?
Pick your favorite study tool

Basilar artery

The basilar artery is a relatively large, robust blood vessel located in the posterior cranial fossa. It is the main blood vessel that forms the posterior circulation of the brain.

This is one of two arterial circuits (the other being the anterior circulation) that delivers up to 15% of the total cardiac output to the brain tissue. This high demand for oxygenated blood is based on the diverse physiological functions that the brain executes on a daily basis. An occlusion of the basilar artery can have debilitating implications, such as speech difficulties, visual disturbances, cranial nerve palsies and altered consciousness. 

Key facts about the basilar artery
Origin Union of the vertebral arteries at the pontomedullary junction
Course Along the basilar groove on the ventral surface of the pons in the pontine cistern
Termination Bifurcates into the paired posterior cerebral arteries
Branches Anterior inferior cerebellar artery
Internal auditory (labyrinthine)artery
Superior cerebellar artery

This article will review the gross anatomy and development of the basilar artery, including the course of its branches. Clinical information regarding lesions of the basilar artery will also be included.

  1. Branches
    1. Anterior inferior cerebellar artery (AICA)
    2. Superior cerebellar artery
    3. Smaller Branches
    4. Posterior cerebral arteries
  2. Circle of Willis
  3. Development
  4. Clinical significance
    1. Stroke (cerebrovascular accident)
  5. Sources
+ Show all


The basilar artery is a large vessel that ascends along the ventral surface of the pons. It originates in the midline at the pontomedullary junction from the union of the vertebral arteries. The vessel then travels in a relatively shallow groove on the pons known as the basilar groove, within the pontine cistern. The lower half of the bony clivus is ventral to the basilar artery. Consequently, it is referred to as the basilar part of the occipital bone

Along its course, the basilar artery gives off five major branches. These are:

  • anterior inferior cerebellar, 
  • internal auditory (labyrinthine), 
  • superior cerebellar, 
  • pontine and 
  • posteromedial arteries.  

The vessel terminates at a bifurcation where it gives off the paired posterior cerebral arteries that contribute to the circle of Willis.

Anterior inferior cerebellar artery (AICA)

The anterior inferior cerebellar artery that arises from the proximal part of the basilar artery is one of the 3 pairs of arteries that supply the cerebellum. It is ventrally related to the abducens (CN VI), facial (CN VII), and vestibulocochlear (CN VIII) nerves. The vessel takes a posterolateral course as it goes to supply the inferior aspect of the cerebellum. It also anastomoses with the posterior inferior cerebellar artery – a branch of the vertebral artery. 

The territory of the cerebellum covered by the anterior inferior cerebellar artery is dependent on the dominance of the posterior inferior cerebellar artery (a branch of the vertebral artery). However, the vessel supplies the anteroinferior surface and flocculus of the cerebellum, middle cerebellar peduncle, and the inferolateral part of the pons. On occasion, the vessels may also reach as far as the proximal medulla oblongata to supply this part of the brainstem

Superior cerebellar artery

Before the basilar artery divides into its terminal branches, it gives off the superior cerebellar artery. This vessel emerges in a lateral direction, caudal to the oculomotor (CN III) nerve. It courses around the cerebral peduncles (pedunculi cerebri) and passes below the trochlear (CN IV) nerve. It eventually gains access to the superior aspect of the cerebellum, which it supplies, along with the tela choroidea of the 3rd ventricle, the pineal body, pons, and superior medullary velum. It also forms an anastomosis with derivatives of the inferior cerebellar arteries.

The function of the superior cerebellar artery is to supply the superior surface of the cerebellum. It also gives unnamed branches to other nearby areas. These include:

  • Pons
  • Superior medullary velum
  • Pineal body
  • Tela choroidea of the third ventricle.

Smaller Branches

Occasionally, a slender internal auditory (labyrinthine) artery arises from the basilar artery. In some instances, this vessel also originates from the superior cerebellar, posterior inferior cerebellar, or anterior inferior cerebellar arteries. Along with CN VII and CN VIII, the artery traverses the internal acoustic meatus to supply the internal ear.

The basilar artery also gives off numerous pontine arteries from its lateral surface (bilaterally) as well as posteromedial (paramedian) arteries from the distal bifurcation. These vessels enter the pons to provide arterial supply.

Posterior cerebral arteries

The basilar artery bifurcates behind the dorsum sellae to form the two posterior cerebral arteries. They travel superior to the smaller superior cerebellar artery and are separated from that artery by CN III. The arteries continue in a course lateral to the midbrain (adjacent to CN IV).

Along their course, they join with the posterior communicating artery to complete the circle of Willis. Subsequently, they course around the pedunculi cerebri toward the tentorial aspect of the cerebrum. Here, they give small terminal branches that supply the occipital and temporal lobes.

Circle of Willis

There is a major communication between the dual supply to the brain. The anterior communicating artery provides communication between the contralateral anterior cerebral arteries. The posterior communicating artery bridges each ipsilateral internal carotid artery with the posterior cerebral artery

Circle of Willis: Diagram

The completed structure is known as the circle of Willis. It surrounds the optic chiasm and infundibulum, as it rests within the chiasmatic and interpeduncular cisterns. The circular anastomosis was initially believed to provide an alternative route for blood flow in the event of vascular occlusion. While that theory still stands, there are additional concepts that suggest the vascular bed may also serve as a pressure relief system to accommodate increased blood flow in instances of raised intracranial pressure.

Take a look at the following resources to cement your knowledge about the basilar artery and nearby arteries of the brain.


The formation of the basilar artery is initiated by the growing brainstem and occipital lobe. Tributaries arising from the internal carotid artery and vertebral arteries all contribute to the formation of the basilar artery. 

Worried about remembering all the arteries of the Circle of Willis? Ease into the topic, practice identifying them and test yourself by using our specially designed Circle of Willis quizzes and unlabeled diagrams!

During the 4th gestational week, the internal carotid artery bifurcates into the anterior and posterior divisions. It is the posterior division that gives rise to the fetal posterior cerebral artery, which eventually feeds the basilar artery. Also developing during the 3rd to 4th gestational week are the carotid-vertebrobasilar anastomoses. In the 5th gestational week, these vessels go on to form the distal portion of the trunk of the basilar artery. 

The paired vertebral arteries develop during the 5th gestational week. They converge in the midline at the pontomedullary junction, where they form the proximal part of the basilar artery. 

Basilar artery: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more.

Kim Bengochea Kim Bengochea, Regis University, Denver
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

Register now and grab your free ultimate anatomy study guide!