Tunica externa

The tunica externa (New Latin "outer coat") — also known as the tunica adventitia (New Latin "additional coat"), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina. The collagen serves to anchor the blood vessel to nearby organs, giving it stability.

Tunica externa
Section of a medium-sized artery.
Part ofWall of blood vessels
LatinTunica externa, tunica adventitia
Anatomical terminology

The three layers of the blood vessels are: an inner tunica intima, a middle tunica media, and an outer tunica externa.

Clinical significance

A common pathological disorder concerning the tunica externa is scurvy, also known as vitamin C deficiency. Scurvy occurs because vitamin C is essential for the synthesis of collagen, and without it, the faulty collagen cannot maintain the vein walls and rupture, leading to a multitude of problems.

Additional images

See also


This article incorporates text in the public domain from page 499 of the 20th edition of Gray's Anatomy (1918)

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