Born circa 304 B.C. on the island of Chios; died circa 250 B.C. (according to some sources, 240 or 280 B.C.) in Alexandria or possibly on the island of Samos. Greek physician.

A student of Theophrastus’, Erasistratus became one of the two principal members of the Alexandrian school of medicine, the other being Herophilus. Erasistratus made a series of anatomical and physiological discoveries through vivisection and the dissection of corpses. He was particularly interested in the brain, in which he sought the source of all human activity. He described the dura mater, the pia mater, the external appearance of the cerebellum, and the nerve tracts proceeding from the brain; he distinguished between motor and sensory nerves. Erasistratus also described gastric peristalsis, the lacteal vessels of the mesentery, the epiglottis, and the trachea. He introduced the term “parenchyma” to designate the belly of a muscle and the soft part of certain internal organs. Erasistratus discovered the function of the cardiac and venous valves; he thought, however, that the veins contained blood and the arteries air. He is credited with introducing the term “artery” (literally, “carrying air”).

Erasistratus believed that intemperate eating and an excess of blood in the veins were the causes of disease; for this reason, the therapy he prescribed generally involved a dietary regimen, bloodletting, or the use of laxatives or emetics. He is said to have invented the catheter. Erasistratus’ works, which are no longer extant, are known from the works of Galen and Caelius Aurelianus.