Clitoris

Clitoris
The internal anatomy of the human vulva, with the clitoral hood and labia minora indicated as lines. The clitoris extends from the visible portion to a point below the pubic bone.
Gray's	subject #270 1266
Artery	Dorsal artery of clitoris, deep artery of clitoris
Vein	Superficial dorsal veins of clitoris, deep dorsal vein of clitoris
Nerve	Dorsal nerve of clitoris
Precursor	Genital tubercle
MeSH	Clitoris
Dorlands/Elsevier	Clitoris

The clitoris is a sexual organ that is present only in female mammals. In humans, the visible button-like portion is located near the anterior junction of the labia minora, above the opening of the urethra and vagina. Unlike the penis, which is homologous to the clitoris, the clitoris does not contain the distal portion of the urethra. The only known exception to this is in the Spotted Hyena. In this species, the urogenital system is unique in that the female urinates, mates and gives birth via an enlarged, erectile clitoris, known as a pseudo-penis.^[1]

In humans, the clitoris is the most sensitive erogenous zone of the female, the stimulation of which may produce sexual excitement and clitoral erection; its continuing stimulation may produce sexual pleasure in the female and orgasm, and is considered the key to females' sexual pleasure.^[2]

Pronunciation and etymology

The word is pronounced /ˈklɪtərɨs/ ( listen) or /klɨˈtɔərɨs/  ( listen). The plural forms are clitorises in English and clitorides in Latin. In slang, it is sometimes abbreviated as clit, which originated in the 1950s. The OED suggests that the pronunciation /ˈklaɪtɒrɪs/) is also used in the UK, and gives the likely etymology as coming from the Greek κλειτορἰς, kleitoris, perhaps derived from the verb κλεἰ-ειν, klei-ein, to shut. The Online Etymology Dictionary states that the etymology of this diminutive is uncertain. Possible etymological candidates are a Greek word meaning "key", "latch", "hook"; a Greek verb meaning "to touch or titillate lasciviously", "to tickle" (the clitoris is called in German slang der Kitzler, "the tickler"), although this verb is more likely derived from "clitoris"; and a Greek word meaning "side of a hill", from the same root as "climax".^[3] Its Latin genitive is clitoridis, as in "glans clitoridis".

Structure

The head or glans of the clitoris is roughly the size and shape of a pea, although it can be significantly larger or smaller.

Human vulva
Human vulva stretched to show externally-visible features of the clitoris in relation to other components: 1. Clitoral hood (prepuce); 2. Clitoral glans; 3. Urethral orifice; 4. Vulval vestibule; 5. Labia minora; 6. Vaginal opening; 7. Labia majora (hair removed); 8. Perineum
MeSH	Vulva
Dorlands/Elsevier	vulva

The clitoris is a complex structure, with both external and internal components. Projecting at the front of the labial commissure where the edges of the outer lips (labia majora) meet at the base of the pubic mound is the clitoral hood (prepuce), which in full or part covers the head (clitoral glans). Following from the head back and up along the shaft, it is found that this extends up to several centimeters before reversing direction, branched resulting in a shape like an inverted "V", and extending as a pair of "legs" known as the clitoral crura formed of the corpora cavernosa, which are concealed behind the labia minora, and terminating attached to the pubic arch, according to some,^[4] or following interior to the labia minora to meet at the fourchette, according to others.^[2]

Associated are the urethral sponge, clitoral/vestibular bulbs, perineal sponge, a network of nerves and blood vessels, suspensory ligaments, muscles and pelvic diaphragm.^[5]

There is considerable variation in how much of the clitoris protrudes from the hood and how much is covered by it, ranging from complete, covered invisibility to full, protruding visibility. An article published in the Journal of Obstetrics and Gynecology in July 1992 states that the average width of the clitoral glans lies within the range of 2.5 to 4.5 millimetres (0.098 to 0.18 in), indicating that the average size is smaller than a pencil-top eraser. Recent discoveries about the size of the clitoris show that clitoral tissue extends some considerable distance inside the body, around the vagina. It is now clear that clitoral tissue is far more widespread than the small visible part most people associate with the word.^[6] There is no identified correlation between the size of a clitoris and a woman's age, height, weight, use of hormonal contraceptives, or being post-menopausal.

Sexual stimulation

Click here to see a video showing clitoris becoming engorged with blood

Most women can only achieve orgasm through clitoral stimulation.^[7][8][9] Masters and Johnson were the first to determine that the clitoral structures surround and extend along and within the labia, determining that all orgasms are of clitoral origin.^[10] More recently, Australian urologist Dr. Helen O'Connell, using MRI technology, noted a direct relationship between the legs or roots of the clitoris and the erectile tissue of the clitoral bulbs and corpora, and the distal urethra and vagina.^[6] She asserts that this interconnected relationship is the physiological explanation for the conjectured G-Spot and experience of vaginal orgasm, taking into account the stimulation of the internal parts of the clitoris during vaginal penetration.^[6][11] "The vaginal wall is, in fact, the clitoris," said O'Connell. "If you lift the skin off the vagina on the side walls, you get the bulbs of the clitoris – triangular, crescental masses of erectile tissue." The idea had been that the clitoris is more than just its glans – the "little hill".^[6]

During sexual arousal and during orgasm, the clitoris and the whole of the genitalia engorge and change color as these erectile tissues fill with blood, and the individual experiences vaginal contractions. Masters and Johnson documented the sexual response cycle, which has four phases and is still the clinically accepted definition of the human orgasm. More recent research has determined that some can experience a sustained intense orgasm through stimulation of the clitoris and remain in the orgasmic phase for much longer than the original studies indicated, evidenced by genital engorgement, color changes, and vaginal contractions.^[12]

Embryonic development

Stages in the development of clitoris

During the development of an embryo, at the time of development of the urinary and reproductive organs, the previously undifferentiated genital tubercle develops into either a clitoris or penis, along with all other major organ systems, making them homologous.^[5] The clitoris is formed from the same tissues that would have become the glans and upper shaft of a penis if the embryo had been exposed to “male” hormones. Changes in appearance of male and female embryos begin roughly eight weeks after conception. By birth, the genital structures have developed into the female reproductive system.^[13]

Embryo sex based on external genitalia is apparent to a doctor at the end of the 14th menstrual week, and the sex can usually be identified by an ultrasound after 16 to 18 menstrual weeks.^[14] A condition that can develop from naturally occurring or deliberate exposure to higher than average levels of testosterone is clitoromegaly.

Recognition of existence

The clitoris has been rediscovered repeatedly over the centuries (Harvey 2001, Laqueur 1989). Over a period of more than 2,500 years, some have considered the clitoris and the penis equivalent in all respects except their arrangement.^[2] Medical literature first recognized the existence of the clitoris in the 16th century. This is the subject of some dispute: Realdo Colombo (also known as Matteo Renaldo Colombo) was a lecturer in surgery at the University of Padua, Italy, and in 1559 he published a book called De re anatomica^[15] in which he described the "seat of woman's delight". Colombo concluded, "Since no one has discerned these projections and their workings, if it is permissible to give names to things discovered by me, it should be called the love or sweetness of Venus."^[16],

Colombo's claim was disputed by his successor at Padua, Gabriele Falloppio (who discovered the fallopian tube), who claimed that he was the first to discover the clitoris. Caspar Bartholin, a 17th-century Danish anatomist, dismissed both claims, arguing that the clitoris had been widely known to medical science since the second century. Indeed, Hippocrates used the term columella (little pillar). Avicenna named the clitoris the albatra or virga (rod). Albucasis, an Arabic medical authority, named it tentigo (tension). It was also known to the Romans, who named it (vulgar slang) landica.^[17]

This cycle of suppression and discovery continued, notably in the work of Regnier de Graaf (Tractatus de Virorum Organis Generationi Inservientibus, De Mulierum Organis Generationi Inservientibus Tractatus Novus) in the 17th century and Georg Ludwig Kobelt (Die männlichen und weiblichen Wollustorgane des Menschen und einiger Säugetiere) in the 19th. De Graaf criticised Columbo's claims for this. (Harvey, Laqueur).

The full extent of the clitoris was alluded to by Masters and Johnson in 1966, but in such a muddled fashion that the significance of their description became obscured. That same year, feminist psychiatrist Mary Jane Sherfey published an article on female sexuality that described in detail the extensive nature of the internal anatomy of the clitoris and in 1981, the Federation of Feminist Women's Health Clinics (FFWHC) continued this process with anatomically precise illustrations.^[2] Today, MRI complements these efforts, as it is both a live and multiplanar method of examination.^[6]

Female genital modification

The external part of the clitoris may be partially or totally removed during female genital cutting, also known as a clitoridectomy, female circumcision, or female genital mutilation (FGM); this may be a voluntary or involuntary procedure. The topic is highly controversial with many countries condemning the traditions that give rise to involuntary procedures, and with some countries outlawing even voluntary procedures. Amnesty International estimates that over 2 million involuntary female circumcisions are being performed every year, mainly in African countries.^[18]

In various cultures, the clitoris is sometimes pierced directly. In U.S. body modification culture, it is actually extremely rare for the clitoral shaft itself to be pierced, as of the already few people who desire the piercing, only a small percentage are anatomically suited for it; furthermore, most piercing artists are reluctant to attempt such a delicate procedure. Some styles, such as the Isabella, do pass through the clitoris but are placed deep at the base, where they provide unique stimulation; they still require the proper genital build, but are more common than shaft piercings. Additionally, what is (erroneously) referred to as a "clit piercing" is almost always the much more common (and much less complicated) clitoral hood piercing.

Enlargement may be intentional or unintentional. Those taking hormones and/or other medications as part of female-to-male transition usually experience dramatic clitoral growth; individual desires (and the difficulties of surgical phalloplasty) often result in the retention of the original genitalia, the enlarged clitoris analogous to a penis as part of the transition. However, the clitoris cannot reach the size of most cissexual men's penises through hormones. Surgery to add function to the clitoris, such as metoidioplasty or clitoral release, are alternatives to phalloplasty (construction of a penis) which permit retention of sexual sensation in the clitoris.

On the other hand, use of anabolic steroids by bodybuilders and other athletes can result in significant enlargement of the clitoris in concert with other masculinizing effects on their bodies. Temporary engorgement results from suction pumping, practiced to enhance sexual pleasure or for aesthetic purposes.

Additional images

Outer anatomy of clitoris.

Muscles of the perineum.

Sagittal section of the lower part of the trunk, right segment.

See also

• Clitoral pump
• Erogenous zone
• Female reproductive system (human)
• Labium (genitalia)

References

Notes

Bibliography

• Chalker, Rebecca (2002). The Clitoral Truth: the secret world at your fingertips. New York: Seven Stories. ISBN 9781583224731. http://books.google.com/?id=m3m3_Uq8qWkC&pg=PA94&lpg=PA94. 
• Harvey, E. (2002) "Anatomies of Rapture: clitoral politics/medical blazons", Signs 27(2) Winter 2002, pp. 315–46
• Laqueur, T. W. (1989) "Amor Veneris, vel Dulcedo Appeletur", in Fragments for a History of the Human Body. #3 Feher, M., Naddaff, R., Tazi, N. (eds.) New York: Zone; pp. 91–131

External links

• BBC News Online (June 11, 2006). "Time for rethink on the clitoris". http://news.bbc.co.uk/1/hi/health/5013866.stm. Retrieved January 2, 2010. 
• "Williamson, S; Nowak, R. The truth about women. New Scientist August 1, 1998 pp. 1–5 (the story of Helen O'Connell". http://www.cirp.org/news/clitoris/.