Overview

The diagram shows the main branches of the blood supply to the brain which includes the carotid and vertebro-basilar systems. The carotid system supplies the brain from the internal carotid – a branch of the common carotid which arises from the aorta. On the right side the common carotid arises from the brachiocephalic artery and on the left it arises as the common carotid as the second branch off the aortic arch It enters the cranial cavity through the cavernous sinus and gives rise to two main branches; the anterior cerebral and the middle cerebral The vertebral arteries usually arise from the subclavian arteries and then travel in the vertebral foramina in the cervical spine. 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. It continues around the pons and midbrain in the ambient and quadrigeminal cisterns and then ascends above the tentorium to end in the occipital lobe. Each of the vessels contributes to the circle of Willis through communicating arteries. The vertebro-basilar system provides the posterior communicating arteries bilaterally and the carotid system provides the anterior communicating arteries via the middle cerebral artery. The PICA or posterior inferior cerebellar artery arises from the vertebral arteries and the anterior inferior cerebellar artery arises from the basilar artery. The superior cerebellar artery arises from the tip of the basilar artery just before it terminates in the posterior cerebral arteries

Courtesy Philips Medical Systems 92492.8

The Vertebral Arteries – MRA

The MRA shows the origin of the vertebral arteries off the subclavian arteries. In this instance the left vertebral is slightly larger than the right. As the vertebral arteries emerge through the foramen magnum they ascend anterior to the medulla and converge to form the basilar artery. The basilar artery ascends on the anterior border of the pons and terminates by branching into the posterior cerebral arteries (PCA).

Courtesy Ashley Davidoff MD Copyright 2010 All rights reserved 73863c01.8s

Vertebral Arteries in the Neck

The axial CT demonstrates the central position of the thyroid in the neck and its relations. Anteriorly a group of muscles called the strap muscles (tan) separate the thr thyroid gland from the skin. The thyroid surrounds the trachea (teal) on its anterior and lateral borders. The esophagus (darker pink) lies posterior to the trachea and medial to the posterior brder of the lobes of the thyroid. The common carotid arteries lie posterior to each of the lobes, while the internal jugular veins lie lateral to the lobes. The prevertebral muscles (light brown) and vertebral arteries (bright red) form posterior relations of the thyroid.

Courtesy Ashley Davidoff MD copyright 2010 all rights reserved 30491c02b02L.9s

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