The male sex organ through which urine and semen pass.
The penis consists mainly of 3 cylindrical bodies of erectile tissue (spongy tissue full of blood vessels) that run along its length.
Two of these bodies, the corpora cavernosa, lie side by side along the upper part of the penis.
The 3rd body, the corpus spongiosum, lies centrally beneath them and expands at the end to form the glans.
Through the centre of the corpus spongiosum runs the urethra, a narrow tube that carries urine and semen out of the body through an opening at the tip of the glans.
Around the erectile tissue is a sheath consisting of fibrous connective tissue enclosed by skin.
Over the glans, the skin forms a fold called the foreskin.
The male organ through which the tubular URETHRA runs from the neck of the URINARY BLADDER to the exterior at the meatus or opening. URINE and SEMEN are discharged along the urethra, which is surrounded by three cylindrical bodies of erectile tissue, two of which (corpora cavernosa) lie adjacent to each other along the upper length of the penis and one (corpus spongiosum) lies beneath them. Normally the penis hangs down in a ?accid state in front of the SCROTUM. When a man is sexually aroused the erectile tissue, which is of spongy constituency and well supplied with small blood vessels, becomes engorged with blood.
This makes the penis erect and ready for insertion into the woman’s vagina in sexual intercourse. The end of the penis, the glans, is covered by a loose fold of skin – the foreskin or PREPUCE – which retracts when the organ is erect. The foreskin is sometimes removed for cultural or medical reasons.
A common congenital disorder of the penis is HYPOSPADIAS, in which the urethra opens somewhere along the under side; it can be repaired surgically. BALANITIS is in?ammation of the glans and foreskin. (See also REPRODUCTIVE SYSTEM; EJACULATION; IMPOTENCE; PRIAPISM.)
n. the male organ that carries the *urethra, through which urine and semen are discharged (see illustration). Most of the organ is composed of erectile tissue (see corpus cavernosum; corpus spongiosum), which becomes filled with blood under conditions of sexual excitement, causing an erection. The erect penis can enter the vagina and ejaculate semen. See also glans; prepuce.
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