Glans
From Wikipedia, the free encyclopedia
The glans (Latin for "acorn", because the glans of a circumcised penis or an uncircumcised penis with the foreskin retracted resembles an acorn in humans) is a structure internally composed of corpus spongiosum in male mammals or of the corpora cavernosa and vestibular tissue in female mammals, including humans. The glans is located at the distal end (tip) of homologous genital structures involved in sexual arousal, the penis in males, and the clitoris in females.
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[edit] Structure
The exterior of the glans consists of a mucous membrane, which is covered to varying degrees by a foreskin (in males) or clitoral hood in females in normal unmodified genitalia. This covering, properly termed the prepuce in both males and females, is normally retractable in adulthood, though it remains attached to the underlying glans in young children.
Under normal circumstances the prepuce gradually becomes a separate, retractable structure during childhood, and is fully retractable by puberty. In some men, the prepuce is too tight to retract comfortably, a condition known as phimosis, and requires medical treatment. If a tight foreskin is withdrawn behind the glans, it can sometimes gets stuck, and cannot be re-extended to its normal position. If this happens, the foreskin can begin to strangulate the glans (particularly if the penis is erect), a condition known as paraphimosis. Paraphimosis requires immediate medical attention.
The prepuce naturally joins with glans around the latter's base, and by the V-shaped frenulum on the inferior (lower) side of the glans in both sexes. In women, the prepuce or clitoral hood is continuous with the superior (upper) junction of the labia minora. In men, the prepuce is a continuation of the skin of the shaft of the penis.
[edit] Hygiene
As with any other body part, regular washing of the glans is beneficial. A whitish substance known as smegma can form between the glans and the prepuce of both sexes and in the folds between the labia of females. While often viewed as disgusting, smegma is normal, and is composed of secretions and sloughed dead cells of the glans and prepuce. Smegma does not usually form in circumcised males, since the glans is exposed and keratinized, and dead cells are merely sloughed off. Retraction of the prepuce and gentle washing of the glans (and between the labial folds in women) is sufficient to remove smegma when it does form.
In rare circumstances and in the absence of regular hygiene, smegma may harden, forming small, rock-like smegmaliths. As well, lack of proper hygiene may lead to the formation of adhesions — physical re-joining of the inner skin of the prepuce to the skin of the glans. Adhesions can make stimulation of the glans and/or movement of the prepuce painful, and in extreme cases may require medical intervention.
[edit] Sex differences
In males the glans is properly known as the glans penis. This is to distunguish it from the homologous female structure, which is properly termed the glans clitoridis, or its English equivalents clitoral glans or (improperly) glans clitoris.
Curiously, in human males, the glans penis flares out from its tip to form a widened corona (lit. "crown") at the base (see image above). The corona is wider than the shaft of the penis, and thus is ultimately the source of the Latin name ("acorn — see above). The human penile corona and has been hypothesized to serve a function in normal human reproduction[citation needed]. There is no corona at the base of the glans penis in other mammals, nor is there any corona at the base of the clitoral glans in humans or other animals.[citation needed] Thus, in all but human males, the glans is about the same size as the adjoining penile shaft in males or the clitoral shaft in females.
In females, the clitoris is superior to (above) the opening of the urinary meatus (the opening of the urethra). In males, the urethra normally passed through the approximate centre of the glans, with the urinary meatus at the tip. Rarely, if the penis did not close normally during embryonic development, the urethra may exit beneath or behind the glans, almost always on the inferior (under) side, a condition known as a hypospadia.
In the male, the glans, as an integral part of the penis, is crucial to the reproductive functions of erection and semen (sperm) delivery. In most females (including humans), the clitoral glans (and clitoris as a whole) is usually considered to serve no function other than sexual arousal. Although important for sexual pleasure and perhaps pair-bonding with mates, the clitoris is believed to be unnecessary for reproduction. The exception to this generalization is in certain species of hyena, where both the urethra and the vaginal canal pass through the clitoris, and exit through the glans clitoridis, making the clitoris necessary for both coitus (sexual intercourse) and parturition (birth).
In women, the glans of the clitoris may be the most highly innervated (and therefore most sensitive) part of the clitoris. However, there is increasing evidence that the deeper parts of the clitoris, including perhaps the G-spot may also be highly innervated. Similarly, in men, the glans is usually considered to be the most highly innervated part of the penis, although there is evidence that the "ridged band" of the foreskin may be even more highly innervated.
In non-technical or sexual discussions, often the words "clitoris" or "clit" refer exclusively to the external glans, excluding the clitoral shaft, clitoral hood, frenulum, and internal roots and body of the clitoris. In men, the glans is clearly part of the penis, although it may be referred to as the "knob" of "head" of the penis, to distinguish it from the shaft.
[edit] Modifications of the glans among humans
By far the most common modification of the glans practiced by humans is circumcision (literally "to cut around") — the surgical removal of part or all of the prepuce, leaving the glans permanently exposed. In some cultures this is a common, though controversial, procedure in men and, particlularly, male infants. More radical is the practice of castration, which, while usually involving removal of just the testicles (orchidectomy), may involve partial or complete removal of the penis (including the glans) in extreme cases.
Similarly, girls and women may be circumcised in some cultures. This may involve removal of just the prepuce (clitoral hood), a situation essentially equivalent to circumcision in the male . Alternatively, female circumcision may also involve the removal of the clitoral glans and other structures (labia minora, labia majora), and partial closure of the vulva (urogenital opening). Female circumcision, particularly where more than the prepuce removed, is highly controversial, and is sometimes referred to as female genital mutilation.
Unlike circumcision, which is often performed on unconsenting infants or children, the external genitalia, including the glans of both sexes, are sometimes voluntarily modified in later life. Included would be certain forms of body art, particularly body piercing of the glans in in both sexes.
