Following his appointment to the Sedlian Professorship of Natural Philosophy at Oxford in 1660, Willis devoted himself to the study of anatomy, beginning with the brain. Cerebri anatome provided a thorough account of the brain and nervous system, which surpassed in detail and precision the fragmentary treatments of the brain that had hitherto appeared. Willis described methods for dissecting the brain, and provided a clear classification of the cranial nerves. He was the first to describe the functional anatomy of the arterial circle at the base of the brain, known as 'the circle of Willis', and is responsible for coining the term 'neurology.' Realising the need for accurate illustrations of the brain, Willis enlisted the assistance of Christopher Wren and Richard Lower, two accomplished artists of anatomy, who together with Thomas Millington, also assisted Willis in the many painstaking dissections.