The Circle of Willis
The Circle of Willis is a roughly circular collection of arteries located at the base of the brain. The arteries that compose the circle are the most common, but not the only, location for Cerebral Aneurysms. It is named for its discoverer, Thomas Willis, a 17th century English physician and Oxford professor who performed detailed anatomical studies on the brain.
The Circle of Willis is composed of
Anterior Communication artery
Left and right Anterior Cerebral artery
Left and right Carotid artery
Left and right Posterior Carotid artery
Left and right Posterior Communicating artery
Though supplying the brain the Basilar and Middle Cerebral arteries are not considered part of the circle.
All of the principal arteries that supply blood to the brain branch off of The Circle of Willis. Blood from the heart is pumped to the Circle of Willis, and it is then distributed to the cerebral hemispheres of the brain. This arrangement of arteries creates a redundancy, or back up in the cerebral circulation. If one of the arteries supplying the circle or a part of the circle itself becomes blocked, blood from the other vessels can frequently preserve the cerebral circulation. Often though, the Circle of Willis is not a complete circle. Only about one third of people have a complete Circle of Willis.
Nothing on this website should, in any way be considered medical advice. It is presented as general information only and is not intended to diagnose or treat any type of medical condition. I am not a doctor, nurse, or any other type of medical or health care professional. Nor am I an expert on Aneurysms. However, I am an expert on the experience of having suffered a ruptured Aneurysm and the subsequent treatment I received. This site should not be considered to be, nor is it intended to be, a definitive source of information regarding Aneurysms. I have made every attempt to ensure the accuracy of any information presented here, but again, I am not a medical professional and my own interpretation of this information could be in error.