Descending thoracic aorta
The aorta is an artery that conveys oxygenated blood from the heart to other parts of the body. It is one of the largest arteries in the body. The aorta gives off several paired branches as it descends. In descending order, these include the
Praxagoras
Praxagoras studied Aristotle's (384-322 BC) anatomy and improved it by distinguishing between artery and veins. He saw arteries as air tubes, similar to the trachea and bronchi, which carried pneuma, the mystic force of life. Arteries took the breath of life from the lungs to the left side of the heart through the aorta to the arteries of the body. He believed the arteries stemmed from the heart, but the veins came from the liver. Veins carried blood, which was created by digested food, to the rest of the body. The combination of blood and pneuma generated heat. As one of the humors, thick, cold phlegm gathered in the arteries would cause paralysis. Also, he believed that arteries were the channels through which voluntary motion was given to the body, and that the cause of epilepsy was the blocking of the aorta by this same accumulation of phlegm.