Circle of Willis and brain circulation Herophilus of Chalcedon (335-280 BC), “Father of Anatomy,” described the vascular structure at the base of the brain which he named the rete mirabile (Latin for “wonderful net”). Although works of Herophilus were tragically destroyed on Julius Caesar’s invasion of Alexandria, some of his teaching can be found in the writings of Galen, who was said to have possessed all his work. Thomas Willis (1621–1675), a physician and Professor of Natural Philosophy at Oxford in the mid-17th century, demonstrated with great precision both the structure and the function of one major anastomotic arterial system. For this reason, the name of this structure is interchangeable, either as Willis’ circle or as Willis’ polygon, being one of the most famous eponymous structures in human anatomy. Satyendra Dhar MD, @DharSaty #circleofwillis #neuroanaromy #cva #baseofbrain #brain #stroke