Aorta
The aorta ( ) is the main artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes oxygenated blood to all parts of the body through the systemic circulation.
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.