Erasistratus of Ceos

304?-250? b.c.

Greek Physician and Anatomist

Acelebrated physician and anatomist, Erasistratus is considered in some circles the founder of physiology for his advancement of anatomy as it related to medical knowledge during his time. He not only studied the structure of the body, but he also tried to explain it in terms of function. Among his many contributions were the ideas that sensory and motors nerves were functionally different and the identification of the proper operation of the epiglottis and the correct function of heart valves. Erasistratus was the first major proponent of a philosophy known as pneumatism. This idea was based on the premise that life depended on a subtle vapor, which was called pneuma. Along with Herophilus (335?-280? b.c.), Erasistratus is also considered to be the cofounder of autopsy, the science of studying human corpses.

Like many of his influential peers, few specifics are known regarding the life of Erasistratus, though it is believed that he was born in 304 b.c. in Ceos, which was part of Greece. Historical records from this time are scarce. Most of the knowledge that we have of him is in relationship to his work and practically nothing is known about his personal life. We can, however, get a rough sketch of his professional life through the historical documents that remain.

The center of Greek culture shifted to Alexandria, Egypt, soon after the time of Aristotle (384-322 b.c.). Erasistratus was one of Alexandria's most famous early residents. He was a teacher at a medical school, which broke with tradition and religious dogma by using dissection of human corpses for study. Up until that time, and also soon afterwards, none of the world's civilizations dissected the human body because it was held in such reverence and awe. Beliefs and fears regarding the soul, life after death, and even resurrection helped to inhibit the use of dissection for study. Knowledge of anatomy and physiology were slowly acquired through ordinary medical treatment, childbirth, and lower animals, but the field of anatomy remained largely incomplete in this regard. Erasistratus and Herophilus used dissection of human cadavers to give anatomy a scientific basis for the first time in history. This was the birth of autopsy as a medical science, effectively breaking an ancient barrier to progress in medicine. Unfortunately, the use of autopsy, and consequently the advancement of human anatomy and physiology, went into a great decline for the next 1,800 years.

Through his anatomical studies, Erasistratus described the major portions of the brain. From his study of nerves, he believed them to be hollow and filled with fluid. He understood the function of the heart valves and named the tricuspid valves based on their appearance. He was not, however, a strong proponent of the tripartite system of humors. This view held that there existed three distinct fluids: the nervous spirit (carried by nerves), animal spirit (carried by the arteries), and blood (carried by the veins). Based on this, Erasistratus expanded the philosophy called pneumatism.

Pneumatism was an ancient school of thought based on the idea that life is dependent upon a vapor or fluid called pneuma. It was an attempt to explain respiration in conjunction with what was believed to be the function of the blood, vessels, and nerves. Erasistratus held that life was intimately connected with pneuma, which was in the air we breathe. He further believed that health and disease resulted from the pneuma. There was a distinction between two types. The first was the "vital spirit" that was formed by the air the heart and transported through the arteries. The second, called the "animal spirit," was formed in the brain from the vital spirit and transported through the body by nerves. Erasistratus believed that any impediment to the action of pneuma would result in disease. While thousands of years of medical science have shown that many of his views were erroneous, Erasistratus remains a prominent figure in medicine because of his tremendous insight and influence.

JAMES J. HOFFMANN