© 2013 WebMD, LLC. All rights reserved. The aorta is the largest artery in the body. The aorta begins at the top of the left ventricle, the heart's muscular pumping chamber. The heart pumps blood from the left ventricle into the aorta through the aortic valve. Three leaflets on the aortic valve open and close with each heartbeat to allow one-way flow of blood. The aorta is a tube about a foot long and just over an inch in diameter. The aorta is divided into four sections: