penis - Structure, Linguistics, Puberty, Erection, Size, Normal variations, Disorders affecting the penis, Penis replacement

A part of the male urogenital system composed mainly of erectile tissue and traversed by the urethra. It has a fixed root and a mobile body. The erectile tissue consists of three longitudinal columns (two corpora cavernosa and the corpus spongiosum). The urethra traverses the corpus spongiosum, which is considerably smaller than the corpora cavernosa. The free end of the corpus spongiosum expands to form the glans penis (which has the slit-like external urethral orifice near its summit). The erectile masses at the root of the penis are covered on their outer surfaces by muscle. The skin over the body of the penis is thin, delicate, freely mobile, and largely free from hairs. Towards the base of the glans penis it forms a free fold (the prepuce or foreskin) which overlaps the glans to a variable extent (the foreskin is surgically removed in circumcision so that the glans is always visible). The size of the penis varies with the amount of blood present within the erectile tissue. Erection builds up as a consequence of various sexual stimuli (pleasurable sights, sound, smell, and other psychic stimuli) reinforced by direct sensory touch (of the body and genital skin). This results in an increase in length and diameter of the penis until it assumes the erect position. Once sexual excitement abates, it returns to its flaccid state. In some mammals (eg dog, bear, baboon) a bone (the os penis) develops in the septum between the two corpora cavernosa.

For the symbol of the erect penis, see phallus.

The penis (plural penises, penes) is an external male sexual organ. The penis is the male reproductive organ and for mammals additionally serves as the external male organ of urination.

Structure

The human penis is made up of three columns of erectile tissue:

the two corpora cavernosa (singular: corpus cavernosum) and one corpus spongiosum

The corpus spongiosum lies on the underside (known also as the ventral side) of the penis;

The end of the corpus spongiosum is enlarged and bulbous-shaped and forms the glans penis. The area on the underside of the penis, where the foreskin is attached, is called the frenum (or frenulum).

The urethra, which is the last part of the urinary tract, traverses the corpus spongiosum and its opening, known as the meatus, lies on the tip of the glans penis.

The raphe is the visible ridge between the lateral halves of the penis, found on the ventral or underside of the penis, running from the meatus (opening of the urethra) across the scrotum to the perineum (area between scrotum and anus).

The human penis differs from those of some other mammals.

Linguistics

Etymology

The word "penis" was taken from Latin and originally meant "tail."

The Latin word "phallus" (from Greek φαλλος) is sometimes used to describe the penis, although "phallus" originally was used to describe images, pictoral or carved, of the penis. The word "penis" from a juvenile perspective is considered inherently funny.

Slang

As with nearly any aspect of the human body that is involved in sex, there are many slang words for the penis.

"Penii" is sometimes facetiously used as a plural form of "penis" instead of "penes" or "penises," its correct form.

Puberty

When a boy enters puberty, after his testicles begin to develop, his penis begins to enlarge, alongside the rest of his genitals. The penis grows longer until about the age of 18, but only growth in width begins at roughly the age of 13.

The glans of the penis is homologous to the clitoral glans;

Erection

An erection is the stiffening and rising of the penis, which occurs in the sexually aroused male, though it can also happen in non-sexual situations. The primary physiological mechanism that brings about erection is the autonomic dilation of arteries supplying blood to the penis, which allows more blood to fill the three spongy erectile tissue chambers in the penis, causing it to lengthen and stiffen. The now-engorged erectile tissue presses against and constricts the veins that carry blood away from the penis. More blood enters than leaves the penis until an equilibrium is reached where an equal volume of blood flows into the dilated arteries and out of the constricted veins; Although many erect penises point upwards (see illustration), it is common and normal for the erect penis to point nearly vertically upwards or nearly vertically downwards or even horizontally straightforward, all depending on the tension of the suspensory ligament that holds it in position.

Size

As a general rule, an animal's penis is proportional to its body size, but this varies greatly between species — even between closely related species. For example, an adult gorilla's erect penis is about 4 cm (1.5 inches) in length; an adult chimpanzee, significantly smaller (in body size) than a gorilla, has a penis size about double that of the gorilla. In comparison, the human penis is larger than that of any other primate, both in proportion to body size and in absolute terms.

While results vary across studies, the general consensus is that the average human penis is approximately 12.7-15 cm (5-5.9 in) in length and 12.3 cm (4.85 in) in circumference when fully erect. The average penis size is slightly larger than the median size.

As with any other bodily attribute, the length and girth of the penis can be highly variable between individuals of the same species. In many animals, especially mammals, the size of a flaccid penis is much smaller than its erect size. erect penis size varies greatly between individuals, such that penis size when flaccid is not a reliable predictor of size when erect.

Except for extreme cases at either end of the size spectrum, penis size does not correspond strongly to reproductive ability in almost any species.

Penis enlargement pills have no documented effect.

Normal variations

Depending on temperature, a flaccid (not erect) penis of average size can withdraw almost completely within the body. During erection the penis will return to its normal (erect) size. Fordyce's spots are small, raised, yellowish-white spots 1-2 mm in diameter that may appear on the penis. Sebaceous prominences are raised bumps similar to Fordyce's spots on the shaft of the penis, located at the sebaceous glands and are normal. Curvature: few penises are completely straight with curves commonly seen in all directions (up, down, left, right). Changes to the curvature of a penis may be caused by Peyronie's disease.

Disorders affecting the penis

Oedema (swelling) of the foreskin can result from sexual activity, including masturbation.

In Peyronie's disease, anomalous scar tissue grows in the soft tissue of the penis, causing curvature.

Penile fracture can occur if the erect penis is bent excessively. The reduced sensations can lead to injuries for either partner and their absence can make it impossible to have sexual pleasure through stimulation of the penis.

Priapism is a painful and potentially harmful medical condition in which the erect penis does not return to its flaccid state.

Developmental disorders of the penis

Hypospadias is a developmental disorder where the meatus is positioned wrongly at birth.

A micropenis is a very small penis caused by developmental or congenital problems.

Diphallia, or penile duplication (PD), is the condition of having two penises.

Alleged and observed psychological disorders

penis panic (koro in Malaysian/Indonesian) - delusion of shrinkage of the penis and retraction into the body. penis envy - the contested Freudian belief of a woman envying men for having a penis.

Altering the male genitalia

Uncircumcised penis (top) compared to a circumcised penis (bottom)

The most prevalent form of genital alteration in some countries is circumcision: removal of part or all of the foreskin for various cultural, religious, and more rarely medical reasons. Less commonly, the penis is sometimes pierced or decorated by other body art. Piercings of the penis include the Prince Albert piercing, the apadravya piercing, the ampallang piercing, the dydoe piercing, and the frenum piercing.

Other practices which alter the penis are also performed, although they are rare in Western societies without a diagnosed medical condition. Apart from a penectomy, perhaps the most radical of these is subincision, in which the urethra is split along the underside of the penis.

Penis replacement

The first successful penis allotransplant surgery was done on September 2005 in a military hospital in Guangzhou, China. (Guangzhou Daily, source) A man at 44 sustained an injury after an accident and his penis was severed;

Non-human penises

Most marsupials, except for the two largest species of kangaroos, have a bifurcated penis. Urban legend alleges that the dolphin has prehensile control over his penis (it is true, however, that whales and dolphins can move and to a certain degree bend their penis tips to facilitate mating). In the realm of absolute size, the smallest vertebrate penis belongs to the common shrew (5 mm or 0.2 inches). Gorillas have relatively small penises, so it is an often used subtle insult in some countries to insinuate or directly state that one is 'hung like a gorilla'.

The Icelandic Phallological Museum is devoted entirely to collecting penis specimens from all the land and sea mammals living in Iceland.

Among birds, only paleognathes (tinamous and ratites) and Anatidae (ducks, geese and swans) possess a penis. It is different in structure from mammal penises, being an erectile expansion of the cloacal wall and being erected by lymph, not blood. The Argentine Blue-bill has the largest penis in relation to body size of all vertebrates; while usually about half the body size (20 cm), a specimen with a remarkable 42.5 cm-long penis is documented. In male insects, the structure homologous to a penis is known as aedeagus.

Cultural aspects involving penises

Uses of animal penises

Culinary, e.g., in Chinese gastronomy Magical and therapeutic, in medicine and/or superstition, especially as an alleged aphrodisiac or even cure for impotence Also used for punitive implements and dog toys, such as the bull pizzle

Uses of human penises in cultural traditions

Aesthetical, e.g., Body modification For the symbolic and artistic use, see under phallus;