ARTERY, DRAWING,Histology of an artery. 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 intima or endartery) with : an elastic internal limiting layer (in white), a basement membrane (in grey) and the endothelium (pavimentous simple epithelium, in brown).