The tunica albuginea is the fibrous envelope that extends the length of the

corpora cavernosa penis A corpus cavernosum penis (singular) (literally "cave-like body" of the penis, plural corpora cavernosa) is one of a pair of sponge-like regions of erectile tissue, which contain most of the blood in the penis during an erection. Such a corpus ...

(containing erectile tissue) and

corpus spongiosum penis The corpus spongiosum is the mass of spongy tissue surrounding the male urethra within the penis. It is also called the corpus cavernosum urethrae in older texts. Anatomy The proximal part of the corpus spongiosum is expanded to form the ure ...

(containing the male

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...

). It is a bi-layered structure that includes an outer longitudinal layer and an inner circular layer. It consists of approximately 5%

elastin Elastin is a protein that in humans is encoded by the ''ELN'' gene. Elastin is a key component of the extracellular matrix in gnathostomes (jawed vertebrates). It is highly elastic and present in connective tissue allowing many tissues in the bod ...

, with the remainder mostly consisting of

collagen Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...

. The tunica albuginea is directly involved in maintaining an erection; that is due to Buck's fascia constricting the erection veins of the penis, preventing blood from leaving and thus sustaining the erect state. The erection veins include the deep dorsal vein, two cavernosal veins, and four para-arterial veins. The

trabecula A trabecula (plural trabeculae, from Latin for "small beam") is a small, often microscopic, tissue element in the form of a small beam, strut or rod that supports or anchors a framework of parts within a body or organ. A trabecula generally ha ...

e of the tunica albuginea are more delicate, nearly uniform in size, and the meshes between them smaller than in the corpora cavernosa penis: their long diameters, for the most part, corresponding with that of the

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do n ...

. The external envelope or outer coat of the corpus spongiosum is formed partly of unstriped muscular fibers, and a layer of the same tissue immediately surrounds the canal of the

Additional images

File:Normal penis ultrasound.jpg,

Medical ultrasonography Medical ultrasound includes diagnostic techniques (mainly medical imaging, imaging techniques) using ultrasound, as well as therapeutic ultrasound, therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal ...

of a normal penis

References

External links

* - "The Male Perineum and the Penis: The Corpus Spongiosum and Corpora Cavernosa"
Image at downstate.edu

Image at downstate.edu
*
Encyclopedia of Reproduction
{{DEFAULTSORT:Tunica Albuginea (Penis) Mammal male reproductive system Human penis anatomy