tunica externa


tunica

 [too´nĭ-kah] (L.) a tunic or coat; used in anatomic nomenclature to designate a membranous covering of an organ or a distinct layer of the wall of a hollow structure, as a blood vessel.tunica adventi´tia the outer coat of various tubular structures.tunica albugi´nea a dense white fibrous sheath that encloses a part or organ, such as the testicle or ovary.tunica conjuncti´va the conjunctiva.tunica dar´tos dartos.tunica exter´na an outer coat, such as the fibroelastic coat of a blood vessel.tunica inter´na an inner coat or layer.tunica in´tima the innermost coat of a blood vessel; called also Bichat's tunic.tunica me´dia the muscular middle coat of a blood vessel.tunica muco´sa the mucous membrane lining of various tubular structures.tunica muscula´ris the muscular coat or layer surrounding the tela submucosa in most portions of the digestive, respiratory, urinary, and genital tracts.tunica pro´pria the proper coat or layer of a part, as distinguished from an investing membrane.tunica sero´sa the membrane lining the external walls of the body cavities and reflected over the surfaces of protruding organs; it secretes a watery exudate.tunica vagina´lis tes´tis the serous membrane covering the front and sides of the testis and epididymis.tunica vasculo´sa a vascular coat, or a layer well supplied with blood vessels.

tu·ni·ca ex·ter·na

[TA] 1. the outer of two or more enveloping layers of any structure; 2. specifically, the outer fibroelastic coat of a blood or lymph vessel. Synonym(s): tunica extima [TA]

tunica externa

The outermost layer of a blood vessel, which envelops the tunica media. It is composed largely of collagen and elastic lamina.
Pathology
The most commonly acquired condition that affects the tunica externa is vitamin C deficiency (scurvy), which results in defective collagen synthesis.

tu·ni·ca ex·ter·na

(tū'ni-kă eks-ter'nă) [TA] 1. The outer of two or more enveloping layers of any structure; 2. Specifically, the outer fibroelastic coat of a blood or lymph vessel.