This layer limits the vessel wall towards the lumen of the vessel and comprises its endothelial lining and associated connective tissue. Beneath the connective tissue, we find the internal elastic lamina, which delimits the tunica intimae from the tunica media. This layer contains mainly endothelial cells.

The tunica media is formed by a layer of circumferential smooth muscle and variable amounts of connective tissue. A second layer of elastic fibers, the external elastic lamina, is located beneath the smooth muscle. It delimits the tunica media from the tunica adventitia. The medial layer of the arterial vessel wall contains vascular smooth muscle cells.

This layer consists mainly of connective tissue fibers. The tunica adventitia blends with the connective tissue surrounding the vessel. The definition of the outer limit of the tunica adventitia is therefore somewhat arbitrary. This layer contains fibroblasts