Blood Supply to The Brain

Definition

Main vessels that supply the brain anastomose at the base of the brain forming a circular network called Circle of Willis

The circle is formed by Right and left main systems of blood vessels

1. Carotid system - consisting of the right and left internal carotids which are branches of the respective common carotids.

2. Vertebral system - consisting of the right and left vertebral arteries which arise from the respetive subclavian arteries.They pass into the cranium travelling through the foramina in the transverse processes of the cervical vertebrae

Parts of the Circle of Willis are:-

Right and left anterior cerebral arteries

One anterior communicating artery - connecting the Right and left anterior cerebral arteries

Right and left posterior communicating arteries - which connect the carotid system and the vertebral system

Right and left posterior cerebral arteries

Basilar artery formed by the union of the right and left vertebral arteries - basilar gives off branches to the right and left.

(anterior, middle and posterior cerebral arteries, anterior and posterior communicating arteries and basilar artery)

Right and left middle cerebral arteries

The basilar artery and middle cerebral arteries, though they supply the brain, are not considered part of the circle.