Penis

penis .jpg

The penis functions as both a part of the urinary system and the reproductive system and its functions include:

  1. Micturition - the penis contains the urethra which carries away urine from the urinary bladder to the external urethral orifice, where it is expelled from the body.

  2. Sexual Intercourse - when the penis becomes erect, ejaculation can occur, thereby allowing semen to move out of the urethra to be deposited into the female reproductive system for reproduction to occur.

The parts of the penis include the following:

  1. Root - located in the pelvic floor, this region contains the erectile tissue and muscles of the penis.

  2. Body - the free portion of the penis, located between the root and the glans. It is composed of the corpus cavernosa and corpus spongiosum.

  3. Glans - this is a distal expansion of corpus spongiosum and contains the opening of the urethra.

The erectile tissues of the penis include:

  1. The right and left crura in the root of the penis, continue anteriorly into the dorsal part of the penis to form 2 corposa cavernosa.

  2. The blub of the penis is located in the midline of the root and it forms the corpus spongiosum, which lies ventrally. The urethra traverses the corpus spongiosum. The distal portion of corpus spongiosum forms the glans penis.

The muscles of the penis include:

  1. A pair of ischiocavernosus muscles which are associated with the left and right crura of the penis. They contract to move blood from the cavernous spaces in the crura into the corpus cavernosa to maintain an erection.

  2. A pair of bulbospongiosus muscles which are associated with the bulb of the penis. These muscles contract to empty the urethra of residual semen or urine. Additionally, by increasing the pressure in the bulb of the penis, these muscles help to maintain an erection.

The penis is also supported by suspensory ligament.

Blood Supply:

The arterial supply is from the deep artery of the penis (involved in the erection of the penis) and dorsal artery of the penis, which arise from the internal pudendal artery.

Venous Drainage:

The deep and superficial dorsal veins of the penis drain it.

Innervation:

The penis is innervated by the pudendal nerve via the dorsal nerve of the penis.