View source for 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  |
}}
{{WikiDoc Cardiology Network Infobox}}
{{CMG}}




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]]
[[Category:Anatomy]]
{{WikiDoc Help Menu}}
{{WikiDoc Sources}}