COSTANZO VAROLIO (CONSTANTIUS Varolius) (1543-1575) was born in Bologna and died in Rome. This professor of anatomy and papal physician was the first to examine the brain from its base up, in contrast with previous dissections of this organ performed from the top down. Varolio was the first to describe many structures, including the pons, which is still known today as the pons Varolli. Varolio was a pupil to the well-known anatomist Aranzio, who was in turn a pupil of Vesalius. Our current understanding of the nervous system is based on the early anatomic descriptions and depictions by such individuals as Varolio.