Illustration of aortic dissection caused by arteriosclerosis (hardening and thickening of the walls of arteries). The tunica media (middle layer of the blood vessel) and the tunica intima (inner layer of the blood vessel) have separated from each other, forming a false lumen. The progression of the disease has led to a life-threatening rupture of the aorta at the level of the descending aorta (far right).