Circle of Willis
The ring-like arterial structure at the base of the brain that provides collateral circulation between the anterior and posterior cerebral circulations.
Full Definition
The Circle of Willis is a critical vascular structure formed by the anterior and posterior cerebral arteries and their communicating vessels. This anatomical configuration provides collateral blood flow pathways that can compensate for arterial occlusions or stenoses. In neuroradiology, assessment of Circle of Willis anatomy and patency is essential for stroke evaluation, surgical planning, and understanding cerebrovascular reserve. Variants in Circle of Willis anatomy are common and can significantly impact patient outcomes in cerebrovascular disease.
Usage
Usage note: Always capitalize when referring to the specific anatomical structure.
In Context
- "The MR angiography demonstrated an incomplete Circle of Willis with absence of the right posterior communicating artery." — Radiology report
- "Collateral flow through the Circle of Willis may compensate for severe carotid stenosis." — Clinical documentation