ARTERY, DRAWING. ARTERY, DRAWING Histology of an artery, with a highlight of the different layers. The inner wall of an artery is constituted by three tuniques, of which each includes one or various tissue layers. From the peripheria towards the light : _ the tunica externa or adventitia, composed mainly of elastic fibers and collagen fibers, _ the tunica media or media with : an elastic external limiting layer in white and a layer of smooth muscle muscularis, in dark brown, _ the tunica or inti