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The tunica media (or just media) ( middle coat ) is the middle layer of an artery
Artery

Arteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood....
 or vein
Vein

In the circulatory system, veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary vein and umbilical veins, both of which carry oxygenated blood....
.

s made up of smooth muscle
Smooth muscle

Smooth muscle is a type of non-striated muscle, found within the tunica media layer of large and small arteries and veins, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye....
 cells and elastic tissue. It lies between the tunica intima
Tunica intima

The tunica intima is the innermost layer of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina....
 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.







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.






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The tunica media (or just media) ( middle coat ) is the middle layer of an artery
Artery

Arteries are blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood....
 or vein
Vein

In the circulatory system, veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary vein and umbilical veins, both of which carry oxygenated blood....
.

Artery

It is made up of smooth muscle
Smooth muscle

Smooth muscle is a type of non-striated muscle, found within the tunica media layer of large and small arteries and veins, the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, respiratory tract, the ciliary muscle, and iris of the eye....
 cells and elastic tissue. It lies between the tunica intima
Tunica intima

The tunica intima is the innermost layer of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina....
 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 lamellę and disposed circularly around the vessel. These lamellę vary in number according to the size of the vessel; the smallest arteries having only a single layer, 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
    Iliac

    Iliac can refer to one of the following:* Iliac artery* Ilium * Iliac veinExcess long comment to prevent listing on...
    , femoral
    Femoral artery

    The femoral artery is a large artery in the muscles of the thigh....
    , and carotid, elastic fibers
    Elastic fibers

    Elastic fibers are bundles of proteins found in extracellular matrix of connective tissue and produced by fibroblasts and smooth muscle cells in artery....
     unite to form lamellę which alternate with the layers of muscular fibers; these lamellę 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
    Aorta

    The aorta is the largest artery in the human body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation....
     and brachiocephalic
    Brachiocephalic artery

    The brachiocephalic artery is an artery of the mediastinum that supplies blood to the right arm and the head and neck.It is the first branch of the aorta, and soon after it emerges, the brachiocephalic artery divides into the right common carotid artery and the right subclavian artery....
    , 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 arrainged in 5 to 7 layers of circular and longitudinal smooth muscle with about 50µ in length and contain well-marked, rod-shaped nuclei
    Cell nucleus

    In cell biology, the nucleus , also sometimes referred to as the "control center", is a membrane-enclosed organelle found in all eukaryote cell ....
    , 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.

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


See also

  • Tunica adventitia
  • Tunica intima
    Tunica intima

    The tunica intima is the innermost layer of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina....


External links

- "Bird, vessels (LM, High)"