ABSTRACT

The aortic wall is composed of three layers: the intima, the media, and the adventitia. The intima is a delicate endothelial layer. The media layer contains relatively little smooth muscle and collagen between mainly elastic fibers arranged in a spiral manner. The adventitia, the outer layer of the aortic wall, is predominantly comprised of elastic tissue, collagen, and the vasa vasorum. The elastic tissue is responsible for the distensibility (elastic recoil) of the aorta (Ao), while the collagen is the main determinant of the tensile strength. The vasa vasorum provides blood flow to the outer half of the aortic wall, including much of the media.