Aristotle's "triventricular" heart and the relevant early history of the cardiovascular system.

Aristotle said that the human heart has three ventricles--right, left, and middle--a concept that has often been viewed as an astonishing error. But was it? Aristotle did not miscount ventricles. In the third century BC, all cardiac chambers were called "ventricles," meaning "cavities." The "ears" (auricles) were distinguished from the "cavities" (ventricles) by Herophilus of Alexandria (c 300 BC) and by Rufus and Ephesus (a contemporary of Jesus Christ). Aristotle regarded the right atrium as a venous dilatation, not as a part of the heart. Aristotle's "right ventricle" was our right ventricle. His "left ventricle" was our left atrium. His "middle ventricle" was our left ventricle. Because he did not count the right atrium, Aristotle considered the human heart to be three-chambered or "triventricular," consisting of the right ventricle, the left atrium, and the left ventricle. This report summarizes the relevant early history of the cardiovascular system.