Circle of Willis | Nimish Shingade

The Circle of Willis is the joining area of several arteries at the bottom (inferior) side of the brain. At the Circle of Willis, the internal carotid arteries branch into smaller arteries that supply oxygenated blood to over 80% of the cerebrum. Although significant anatomic variations exist, the circle of Willis is typically composed of three cerebral and two communicating arteries that link the internal carotid arteries and the vertebrobasilar system. The internal carotid arteries supply most of the forebrain. The most common anomaly of the circle of Willis in normal brains was hypoplasia of one or other components of the circle. Arteries of less than 1 mm in external diameter were considered hypoplastic, except for the communicating arteries, where less than 0.5 mm was considered hypoplastic.