Tunica media 2477478 174667755 2007-11-29T20:02:36Z Kuebi 3115875 +[[de:Tunica media]] {{Infobox Anatomy | Name = {{PAGENAME}} | Latin = tunica media vasorum | GraySubject = 133 | GrayPage = 498 | Image = Illu_artery.jpg | Caption = Artery wall | Image2 = Gray448.png | Caption2 = Transverse section through a small [[artery]] and [[vein]] of the [[mucous membrane]] of the [[epiglottis]] of a child. (Tunica media is at 'm') | System = | MeshName = Tunica+Media | MeshNumber = A02.633.570.491.800 | DorlandsPre = t_22 | DorlandsSuf = 12831907 | }} The '''tunica media''' (or just '''media''') is the middle layer of an [[artery]] or [[vein]].<ref>{{BUHistology|05102loa}}</ref> ==Artery== It is made up of [[smooth muscle]] cells and [[elastic tissue]]. It lies between the [[tunica intima]] on the inside and the [[tunica adventitia]] on the outside. The middle coat (tunica media) is distinguished from the inner by its color and by the transverse arrangement of its fibers. * In the ''smaller arteries'' it consists principally of plain muscle fibers in fine bundles, arranged in [[lamellæ]] and disposed circularly around the vessel. These lamellæ vary in number according to the size of the vessel; the smallest arteries having only a single layer<ref>{{BUHistology|21103loa}}</ref>, and those slightly larger three or four layers. It is to this coat that the thickness of the wall of the artery is mainly due. * In the ''larger arteries'', as the [[iliac]], [[Femoral artery|femoral]], and [[carotid]], [[elastic fibers]] unite to form lamellæ which alternate with the layers of muscular fibers; these lamellæ are united to one another by elastic fibers which pass between the muscular bundles, and are connected with the fenestrated membrane of the inner coat. * In the ''largest arteries'', as the [[aorta]]<ref>{{OklahomaHistology|66_02}} - "Aorta"</ref> and [[Brachiocephalic artery|brachiocephalic ]], the amount of elastic tissue is very considerable; in these vessels a few bundles of white connective tissue also have been found in the middle coat. The muscle fiber cells are about 50μ in length and contain well-marked, rod-shaped [[cell nucleus|nuclei]], which are often slightly curved. ==Vein== The middle coat is composed of a thick layer of connective tissue with elastic fibers, intermixed, in some veins, with a transverse layer of muscular tissue. <ref>{{BUHistology|05603loa}}</ref> The white fibrous element is in considerable excess, and the elastic fibers are in much smaller proportion in the veins than in the arteries. ==Additional images== <gallery> Image:Illu vein.jpg|Vein Image:Anatomy_artery.png|Anatomy of the arterial wall Image:Gray450.png|Section of a medium-sized artery. </gallery> ==See also== * [[Tunica adventitia]] * [[Tunica intima]] ==References== <references/> ==External links== * {{UCDavisOrganology|Circulatory/vessels/vessels7/vessels3}} - "Bird, vessels (LM, High)" {{Gray's}} [[Category:Arteries]] [[de:Tunica media]] [[fr:Media (artère)]]