An elastic artery and the largest blood vessel in the vertebrate body, the aorta distributes blood from the heart to the circulatory system. Oxygenated blood is pumped into the aortic arch from the left ventricle. Several small arteries branch from the top of this arch to deliver blood to the head and upper torso. The aorta then curves sharply back to become the dorsal aorta, which runs parallel to the spinal column before it branches into many smaller arteries that supply blood to the rest of the body.

Like all other large blood vessels, the aorta is composed of three layers called tunicas. The interior layer, or tunica intima, is composed of a lining of very thin, flat endothelial cells that sit on a thin connective tissue layer called the basal lamina. The middle layer, or tunica media, is the thickest and most unique part of the aorta...