Circle of Willis is a system of arteries, schematically shaped like a circle. It ensures the vascularization (therefore oxygenation) of the brain. This arterial circle is located in the center of the brain / skull. The Willis polygon has the particularity of relating the different arteries arriving to the brain, namely the carotid arteries and the vertebrobasilar system. This anastomosis system allows the brain to receive blood even if one of the arteries in the neck is stenosed.
Circle of Willis is made up of :