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Vagina
Vagina in the female human reproductive system.
Vulva with vaginal opening
Details
Precursor	urogenital sinus and paramesonephric ducts
Artery	superior part to uterine artery, middle and inferior parts to vaginal artery
Vein	uterovaginal venous plexus, vaginal vein
Nerve	Sympathetic: lumbar splanchnic plexus Parasympathetic: pelvic splanchnic plexus
Lymph	upper part to internal iliac lymph nodes, lower part to superficial inguinal lymph nodes
Identifiers
Latin	"sheath" or "scabbard"
MeSH	D014621
TA98	A09.1.04.001
TA2	3523
FMA	19949
Anatomical terminology[edit on Wikidata]

The vagina (from Latin vāgīna, literally "sheath" or "scabbard") is a fibromuscular tubular tract which is a sex organ and has two main functions; sexual intercourse and childbirth. In humans, this passage leads from the opening of the vulva to the uterus (womb), but the vaginal tract ends at the cervix. Unlike men, who have only one genital orifice, women have two, the urethra and the vagina. The vaginal opening is much larger than the urethral opening, and both openings are protected by the labia. The inner mould of the vagina has a foldy texture which can create friction for the penis during intercourse. During arousal, the vagina gets moist to facilitate the entrance of the penis.

The Latinate plural "vaginae" is rarely used in English. The word vagina is often used colloquially to refer to the vulva or to the female genitals in general; technically, the vagina is the specific internal structure.

Location and structure

The human vagina is an elastic muscular canal that extends from the cervix to the vulva. It consists of three layers of tissue: the mucosa is the layer on the surface that can be touched, which consists of mucous membranes and is a surface similar to the lining of the mouth.

Although there is wide anatomical variation, the length of the unaroused vagina of a woman of child-bearing age is approximately 6 to 7.5 cm (2.5 to 3 in) across the anterior wall (front), and 9 cm (3.5 in) long across the posterior wall (rear). During sexual arousal the vagina expands in both length and width. Its elasticity allows it to stretch during sexual intercourse and during birth to offspring. The vagina connects the superficial vulva to the cervix of the deep uterus.

If the woman stands upright, the vaginal tube points in an upward-backward direction and forms an angle of slightly more than 45 degrees with the uterus. The vaginal opening is at the caudal end of the vulva, behind the opening of the urethra. The upper one-fourth of the vagina is separated from the rectum by the recto-uterine pouch. Above the vagina is the Mons pubis. The vagina, along with the inside of the vulva, is reddish pink in color, as are most healthy internal mucous membranes in mammals. A series of ridges produced by folding of the wall of the outer third of the vagina is called the vaginal rugae. They are transverse epithelial ridges and their function is to provide the vagina with increased surface area for extension and stretching.

Vaginal lubrication is provided by the Bartholin's glands near the vaginal opening and the cervix. The membrane of the vaginal wall also produces moisture, although it does not contain any glands. Before and during ovulation, the cervix's mucus glands secretes different variations of mucus, which provides an alkaline environment in the vaginal canal that is favorable to the survival of sperm. "Vaginal lubrication typically decreases as women age, but this is a natural physical change that does not normally mean there is any physical or psychological problem. After menopause, the body produces less estrogen, which, unless compensated for with estrogen replacement therapy, causes the vaginal walls to thin out significantly."

The hymen is a membrane of tissue that surrounds or partially covers the external vaginal opening. The tissue may or may not be ruptured by vaginal penetration. It can also be ruptured by delivery, a pelvic examination, injury, or sports. The absence of a hymen may not indicate prior sexual activity. Similarly, its presence may not indicate a lack of prior sexual activity.

Function

The vagina has several biological functions.

Sexual activity

The concentration of the nerve endings that lie close to the entrance of a woman's vagina (the lower third) can provide pleasurable sensation during sexual activity when stimulated in a way that the particular woman enjoys. However, the vagina as a whole has insufficient nerve endings for sexual stimulation and orgasm, which is considered to make the process of child birth significantly less painful. "The outer one-third of the vagina, especially near the opening, contains nearly 90 percent of the vaginal nerve endings and therefore is much more sensitive to touch than the inner two-thirds of the vaginal barrel."

Research has found that clitoral tissue extends considerably into the vulva and vagina. During sexual arousal, and particularly the stimulation of the clitoris, the walls of the vagina self-lubricate. This reduces friction that can be caused by various sexual activities. With arousal, the vagina lengthens rapidly, to an average of about 4 in.(10 cm), but can continue to lengthen in response to pressure. As the woman becomes fully aroused, the vagina tents (last ²⁄₃) expands in length and width, while the cervix retracts. The walls of the vagina are composed of soft elastic folds of mucous membrane which stretch or contract (with support from pelvic muscles) to the size of the inserted penis or other object, stimulating the penis and helping to cause the male to experience orgasm and ejaculation, thus enabling fertilization.

An erogenous zone commonly referred to as the G-Spot (also known as the Gräfenberg Spot) is typically defined as being located at the anterior wall of the vagina, about five centimeters in from the entrance. Some women experience intense pleasure if the G-Spot is stimulated appropriately during sexual activity. A G-Spot orgasm may be responsible for female ejaculation, leading some doctors and researchers to believe that G-Spot pleasure comes from the Skene's glands, a female homologue of the prostate, rather than any particular spot on the vaginal wall. Other researchers consider the connection between the Skene's glands and the G-Spot to be weak. They contend that the Skene's glands do not appear to have receptors for touch stimulation, and that there is no direct evidence for their involvement.

The G-Spot's existence, and existence as a distinct structure, is still under dispute, as its location can vary from woman to woman and appears to be nonexistent in some women, and it is hypothesized to be an extension of the clitoris.

Childbirth

During childbirth, the vagina provides the channel to deliver the infant from the uterus to its independent life outside the body of the mother. During birth, the elasticity of the vagina allows it to stretch to many times its normal diameter. The vagina is often typically referred to as the birth canal in the context of pregnancy and childbirth, though the term is, by definition, the area between the outside of the vagina and the fully dilated uterus.

Uterine secretions

The vagina provides a path for menstrual blood and tissue to leave the body. In industrial societies, tampons, menstrual cups and sanitary napkins may be used to absorb or capture these fluids.

Clinical relevance

The vagina is self-cleansing and therefore usually needs no special treatment. Doctors generally discourage the practice of douching. Since a healthy vagina is colonized by a mutually symbiotic flora of microorganisms that protect its host from disease-causing microbes, any attempt to upset this balance may cause many undesirable outcomes, including but not limited to abnormal discharge and yeast infection. The acidity of a healthy vagina of a woman of child-bearing age (a pH of around 4.5) is due to the degradation of glycogen to the lactic acid by enzymes secreted by the Döderlein's bacillus. This is a normal commensal of the vagina. The acidity retards the growth of many strains of dangerous microbes.

The vagina is examined during gynecological exams, often using a speculum, which holds the vagina open for visual inspection of the cervix or taking of samples (see pap smear). Medical activities involving the vagina, including examinations, administration of medicine, and inspection of discharges, are also referred to as being per vaginam (or p.v.).

Vaginismus

Vaginismus, not to be confused with Vaginitis, refers to an involuntary tightening of the vagina, due to a conditioned reflex of the muscles in the area. It can affect any form of vaginal penetration, including sexual intercourse, insertion of tampons and menstrual cups, and the penetration involved in gynecological examinations. Various psychological and physical treatments are possible to help alleviate it.

Signs of disease

Vaginal diseases present with lumps, discharge and sores.

Lumps

The presence of unusual lumps in the wall or base of the vagina is always abnormal. The most common of these is Bartholin's cyst. The cyst, which can feel like a pea, is formed by a blockage in glands which normally supply the opening of the vagina. This condition is easily treated with minor surgery or silver nitrate. Other less common causes of small lumps or vesicles are herpes simplex. They are usually multiple and very painful with a clear fluid leaving a crust. They may be associated with generalized swelling and are very tender. Lumps associated with cancer of the vaginal wall are very rare and the average age of onset is seventy years. The most common form is squamous cell carcinoma, then cancer of the glands or adenocarcinoma and finally, and even more rarely, melanoma.

Discharge

The great majority of vaginal discharges are normal or physiological and include blood or menses (from the uterus), the most common, and clear fluid either as a result of sexual arousal or secretions from the cervix. Other non infective causes include dermatitis, discharge from foreign bodies such as retained tampons or foreign bodies inserted by curious female children into their own vaginas. Non-sexually transmitted discharges occur from bacterial vaginosis and thrush or candidiasis. The final group of discharges include the sexually transmitted diseases gonorrhea, chlamydia and trichomoniasis. The discharge from thrush is slightly pungent and white, that from trichomoniasis more foul and greenish, and that from foreign bodies resembling the discharge of gonorrhea, greyish or yellow and purulent (like pus).

Sores

All sores involve a breakdown in the walls of the fine membrane of the vaginal wall. The most common of these are abrasions and small ulcers caused by trauma. While these can be inflicted during rape most are actually caused by excessive rubbing from clothing or improper insertion of a sanitary tampon. The typical ulcer or sore caused by syphilis is painless with raised edges. These are often undetected because they occur mostly inside the vagina. The sores of herpes which occur with vesicles are extremely tender and may cause such swelling that passing urine is difficult. In the developing world a group of parasitic diseases also cause vaginal ulceration such as Leishmaniasis but these are rarely encountered in the west. HIV/AIDS can be contracted through the vagina during intercourse but is not associated with any local vaginal or vulval disease. All the above local vulvovaginal diseases are easily treated. Often only shame prevents patients from presenting for treatment.

Route of administration

Intravaginal administration is a route of administration where the substance is applicated inside the vagina. Pharmacologically, it has the potential advantage to result in effects primarily in the vagina or nearby structures (such as the vaginal portion of cervix) with limited systemic adverse effects compared to other routes of administration.

In other animals

The vagina (along with the penis) is a general feature of animals in which the female is internally fertilised (other than by traumatic insemination). The shape of the vagina varies among different animals.

In placental mammals and marsupials, the vagina leads from the uterus to the exterior of the female body. In birds, monotremes, and some reptiles, it is the homologous part of the oviduct and leads from the shell gland to the cloaca. In some jawless fish, there is no oviduct nor vagina and instead the egg travels directly through the body cavity (and is fertilised externally as in most fish and amphibians). In insects and other invertebrates the vagina is part of the oviduct (see insect reproductive system).

See also

• Cunnilingus
• Cunt
• Gynoecium
• Human sexuality
• Kegel exercise
• Masturbation
• Menstruation
• Pubic hair

References

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External links

The dictionary definition of vagina at Wiktionary

Template:Link GA Template:Link GA

• Female reproductive system
• Reproductive system