The
mainline.
The principle artery in humans, the aorta brings oxygen-rich blood to all other arteries except those of the lungs. The aorta begins at the left ventricle of the heart and supplies O first to the heart, then the head and arms followed by the torso/waist...from here the aorta enters the abdomen via the aortic hiatus and feeds blood to your guts before dividing into the two iliac arteries and traveling down your legs.
The lining of the aorta is elastic.