Basics of the Basilar Artery

From Origin to Termination

The diagram shows the main branches of the basilar artery. The basilar artery is formed by the two vertebral arteries and travel as a single artery over the upper medulla and the entire pons. Its terminal division is into the right and left posterior cerebral arteries. Its first branch after this division is the posterior communicating artery.

Courtesy Ashley Davidoff MD copyright 2010 all rights reserved  97194b06b.8s

Advanced Look at the Basilar Artery

The diagram shows the main branches of the vertebro-basilar system. As the vertebral arteries emerge through the foramen magnum they give rise to the posterior inferior cerebellar artery. Shortly thereafter and just prior to converging to form the basilar artery, each of the vertebral arteries gives off a branch to create the anterior spinal artery. The basilar artery is formed by the two vertebral arteries and travels as a single artery over the upper medulla and the pons, The basilar artery ascends on the anterior border of the pons and one of its first major branches is the anterior inferior cerebellar artery (AICA). This is followed by multiple small branches to the pons (pontine arteries)and as it approaches its cranial extent it first gives rise to a pair of superior cerebellar arteries and then to the posterior cerebral arteries (PCA). The first major branch off the PCA is the posterior communicating artery. The posterior communicating artery on each side inserts into the trifurcation of the confluence of the termnation of the internal carotid, middle cerebral artery and the anterior cerebral artery.

Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 97194b12b.8sg02.8s

The Vertebral Arteries

Part of the vertobasilar System

The diagram shows the main branches of the blood supply to the brain including the circle of Willis overlaid on coronal MRI image to portray the approximate position of the vessels in the brain. The image on the right shows the combined system all in red, and the image on the right shows the derivation from the vertebrobasilar and carotid systems The carotid system supplies the brain from the internal carotid (salmon pink). We demonstrate its terminal bifurcation into middle cerebral (dark green) and anterior cerebral (bright green). The anterior communicating artery runs between the two anterior cerebrals (bright red) The basilar artery (pink) is formed by the two vertebral arteries and it travels as a single artery over the upper medulla and the pons. Its terminal branch is the posterior cerebral artery (maroon). The first branch off the posterior cerebrals is the posterior communicating which joins the middle cerebral to complete the circle of Willis Each of the carotid and vertebro-basilar systems contributes to the circle of Willis through communicating arteries. The vertebro-basilar system provides the posterior communicating arteries bilaterally from the posterior cerebral and the carotid system provides the anterior communicating arteries via the anterior cerebral arteries.

Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 89721c06b.8sg05.8s

The Vertebral Artery and Major Branches

Selective Angiogram in the A-P Projection

The selective of the left vertebral artery in the A-P projection reveals the major intracranial branches; The posterior inferior cerebellar artery (PICA) which supplies the inferior aspect of the cerebellum The two vertebral arteries join to form the basilar artery which runs on the anterior surface of the pons. Its first branch is the; anterior inferior cerebellar artery ( AICA) which supplies the middle portion of the cerebellum and then the basilar artery gives off the superior cerebellar artery which supplies the superior aspect of the cerebellum The basilar artery finally terminates in the two posterior cerebral arteries (PCAs) which give off the posterior communicating arteries which connect with the circle of Willis and feed the inferior portion of the temporal lobes and the occipital lobes.

Courtesy Elisa Flower MD and Alex Norbash MD Copyright 2010 97629b.8s

The Slective Angiogram in the Lateral Projection

The selective angiogram of the vertebral artery in the lateral projection reveals the major intracranial branches; The posterior inferior cerebellar artery (PICA) which supplies the inferior aspect of the cerebellum The two vertebral arteries join to form the basilar artery which runs on the anterior surface of the pons. Its first branch is the; anterior inferior cerebellar artery ( AICA) which supplies the middle portion of the cerebellum and then the basilar artery gives off the superior cerebellar artery which supplies the superior aspect of the cerebellum (not easily distinguished in this view The basilar artery finally terminates in the two posterior cerebral arteries (PCAs) which give off the posterior communicating arteries which connect with the circle of Willis. The PCA feeds the inferior portion of the temporal lobes and the occipital lobes. The anterior cerebral artery is seen filling from the circle of Willis

Courtesy Elisa Flower MD and Alex Norbash MD Copyright 2010 97630b02.8s

Basilar Tip Aneurysm

The axial rendering (a) and coronal rendering (b) image of the vertebro- basilar circulation looking into the middle and posterior cranial fossa with the circle of Willis in view shows a basilar tip aneurysm.

Courtesy Philips Medical Systems 92584c

Fusiform Aneurysm of the BA\asilar Artery

The MIP (left) and 3D volume rendered (right) image of the vertebro- basilar circulation looking into the middle and posterior cranial fossa shows a diffuse fusiform aneurysm of the basilar artery.

Courtesy Philips Medical Systems 92415c.8