The-Clitoris.com: Anatomy and Function of the Vagina and Pelvic Muscles Part 2

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Jump to Developmental Anomalies
Jump to The Protective Vaginal Environment
Jump to Vaginal and Vulvar Fluids
Jump to Normal Vaginal and Vulvar Fluids (Photographs)
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Anatomy Index

Nerves of Vagina and Pelvis

The vagina doesn't share the same nervous system throughout, as indicated in the following illustrations. The outer one-third of the vagina is part of the somatic nervous system while the inner two-thirds is part of the autonomic nervous system, and there is a region where the two nervous systems are intermixed. This means the outer vagina is sensitive to the full range of sensations, but the inner vagina is sensitive primarily to pressure and pain. The most complex area of innervation is likely that of the female prostate, as the nerves for the vagina, prostate, and urethra are potentially intermingled, but at a minimum are in very close proximity. This is perhaps why 63 percent of women have indicated the front wall of their vagina is the most sensitive to stimulation. Childbirth, pelvic surgery, and trauma to the clitoris and vulva may adversely affect sexual sensitivity and sensation.

Clinically Oriented Anatomy: Fifth Edition
Copyright 2006 Lippincott Williams & Wilkins.

The area highlighted in tan (vulva, anus, outer vagina) is supplied by the somatic nervous system, the areas highlighted in green and yellow (internal organs) are part of the autonomic nervous system.

Clinically Oriented Anatomy: Fifth Edition
Copyright 2006 Lippincott Williams & Wilkins.

The vaginal nerves indicated in green are sensitive to the full range of sensation, those in orange are primarily sensitive to pressure and pain. The location of diseases and injuries affecting the nervous system will determine which organs retain sensitivity, and the type of sensations possible in those areas, though individual experiences do vary.

Blood Supply of Vagina

The blood supply to the vagina, pelvic organs, and vulva is extremely important to female sexual arousal and pleasure. Without adequate blood flow vaginal lubrication may be insufficient and vaginal and vulvar sensitivity decreased. All forms of vascular disease, including cardiovascular disease, are likely to adversely influence female sexual function. Pelvic surgery, including hysterectomy, may alter blood flow to the pelvic and sexual organs. Good general health is essential to good sexual health and performance.

http://en.wikipedia.org/wiki/Vaginal_artery
Additional illustrations can be seen by clicking here.

Developmental Anomalies

The manner in which the internal female reproductive organs form during fetal development may result in some structural abnormalities that alter the appearance and function of the vagina:

There may be a complete absence of a vagina.

A longitudinal vaginal septum may form resulting in the appearance of two vaginas located side-by-side.

A transverse vaginal septum may form resulting in a partial or complete blockage of the vagina, perhaps giving the appearance of a short vagina. This may prevent menses from exiting the body, resulting in abdominal menstrual discomfort but no menstrual discharge.

The Protective Vaginal Environment

It may surprise you to know there is a vibrant and essential ecosystem within the vagina that helps protect women from disease. During early childhood, from the age of a few months until the age of eight to thirteen, the vaginal environment is relatively dormant, but with the onset of puberty that quickly changes.(4) The reason being, with puberty comes the desire to reproduce, to participate in partnered sex, which exposes a woman's vagina to body fluids and living organisms from her sexual partner(s). The onset of menstrual bleeding during puberty may also provide a food source for potentially harmful organisms. Our internal body, below the surface of the skin, has defenses against harmful invasions that cause disease, but it is much safer if the potentially harmful organisms are kept totally outside of the body, and this is the reason for the protective vaginal environment.

The vaginal and vulvar environment creates greater risk for women than men when it comes to sexually transmitted diseases, especially compared to uncircumcised men.(7) The reason being, during vaginal intercourse, if barriers to the transfer of body fluids aren't used, namely condoms and other safe sex practices, then body fluids (smegma and ejaculate) and skin cells from the body and penis, if her partners are male, and body fluids (vaginal and vulvar) and skin cell from the body and vulva, if her partners are female, are potentially deposited within the vagina. The vagina is a dark, warm, and moist environment that is suitable for microscopic organisms to live, and more importantly, reproduce and colonize. An army of one bacterium isn't much of a hazard, an army of trillions is. To ward off this invasion, the vagina develops a defensive army of it own, an army of beneficial bacteria. In the case of the vagina, "clean and sterile" is absolutely not of benefit. The last thing a woman should do, or feel compelled to do, is clean her vagina, as this is potentially harmful to her and her vagina.

To see an animation showing the cycle of
the vaginal ecosystem please click here.
Animation is 2.3 megabytes in size.

The vaginal environment is normally acidic, but the level of acidity varies throughout the menstrual cycle:

"Vaginal pH varies a lot during the cycle too. At the start of menstrual flow, the pH is already increased, peaking at around 7.0. The pH then drops sharply to between 4.0 and 4.5 over the next three days and remains constant until day 21, although it may rise slightly with ovulation. Bacterial populations show great variations during the menstrual cycle; as would be expected, they are highest in the menstrual flow, possibly because menstrual blood acts as source of nutrition, or because of the rising pH associated with menstrual blood." [1]

The normally acidic vaginal environment is potentially harmful to organisms that enter the vagina, including sperm, which could pose a barrier to reproduction. To the healthy vagina and body, sperm are seen as a potentially harmful invader, as they are a living organism with DNA different from your own. To help overcome this, during sexual arousal the vaginal lubricant reduces the acidic level of the vagina, allowing sperm to survive as they travel through the vagina.[1] Women who experience sexual arousal on a frequent basis may have a less acidic vaginal environment than those who do not, because the vagina doesn't have time to return to a more acidic state between periods of arousal, which MAY expose women to increased risk for infection. "It can take up to eight hours after intercourse for the pH to return to normal; women who are very sexually active rarely possess a vaginal bacterial population characteristic of low (4.5) pH."[1]

Becoming sexually aroused a hundred times a day or engaging in partnered sex equally as often IS NOT a problem, AS LONG AS you don't expose yourself to disease in the process. Frequent sexual arousal, something you likely have no control over, isn't harmful, nor is frequent partnered sex with the same healthy partner, nor is masturbation. The increased risk results from exposure to pathogens. The greater the number of sexual partners, the greater the chances you will be exposed to disease.

This is why it is important to limit the number of sexual partners you have, and to be sure your partner, and objects that you insert into the vagina, are clean and disease free. Pathogens are microscopic, meaning you can't tell by looking whether your sexual partner has them. Condoms are a must, even if you are using another form of birth control. Condoms should be used because male ejaculate also reduces the acidity of the vagina, potentially increasing the chances for a vaginal infection following intercourse. You should also use reasonable care when masturbating, by keeping objects you insert into your vagina clean.

Notes:

Soap is potentially harmful to the vagina and vulva, when you use soap to wash your hands and objects you insert into your vagina, be sure to rinse them thoroughly with clean water. Don't use soap on the vulva or in the vagina, only rinse the vulva with clean water: the vagina cares for itself.

The vagina may be abraded, scratched, or cut when inserting a tampon applicator or during normal sexual activity, alone and with a partner, which may allow the body to be invaded by potentially harmful organisms. Toxic Shock Syndrome is an example of when the body's defenses are unable to ward off an invading organism inside the vagina. The injury doesn't cause the infection, rather it allows pathogens to more easily enter the body, IF they are present. Many potentially harmful organisms are normally found inside the vagina, but a healthy vaginal environment helps keep them from becoming sufficient in number to cause harm.

When the protective vaginal environment is out of balance, bacterial vaginosis (BV) may result. Symptoms of BV include abnormal discharge, odor, pain, itching, or burning. BV is the most common gynecological complaint.

Vaginal and Vulvar Fluids

There are several body fluids that may appear at the vestibule, especially with the onset of puberty, though some vaginal fluids are present throughout life. During the reproductive years the amount of fluid is normally increased, though the amount is dependent on medications and birth control methods prescribed by your doctor. Based on emails I receive, it appears some teens and young women are totally unaware of their normal daily vaginal fluids, at least until they engage in some new activity, like partnered sex, then fearing a negative consequence to that activity, they mistake their normal vaginal fluids for an indication of disease. At the onset of puberty girls should be made aware of the normal cycle of these fluids, so they will have a better understanding of how their body normally works, and wont mistake the normal for being abnormal.

Contributors to the vaginal and vulvar fluids [1]:

Oil and sweat from oil and sweat glands of the vulva [Sebaceous glands]

Secretions from the specialized vulvar glands called Bartholin's and Skene's glands [Female Prostate]

Moisture that comes through the vaginal walls (called transudate) [Vaginal lubrication]

Cells shed from vaginal walls

Mucus from the cervix

Fluid from the Fallopian tubes and uterus

Products from the bacteria that live in the vagina [slightly acidic fluid and waste]

Salt water (physiologic [normal] saline [salt containing water] that makes up most bodily fluids and mucus)

[Prostatic fluids, including prostate-specific antigen (PSA) and mucus]

[Menstrual fluid, menses]

Indications of normal vaginal fluids:

"Depending on the time of the menstrual cycle, secretions make a clear, milky white, or faintly yellow discharge. Sometimes there is a stringy mucus. The discharge may be somewhat slippery or clumpy. Most women have small white or yellow stains on their underwear, varying with their menstrual cycles. Normal secretions also form small dry yellow-white flakes or clumps in the pubic hair surrounding the vaginal opening. Some women have enough normal secretions to make them feel wet all the time. What if you never notice any discharge? That's normal too. Your secretions probably remain in the vagina without appearing on the outside."

"The important thing is that normal secretions do not itch, burn, or irritate. Normal secretions do not have a bad odor, although secretions that stay on the underwear may develop a slightly sour smell. Normal secretions do not contain and blood, even in microscopic amounts."

"Some women complain of having too much vaginal discharge all the time, so heavy in fact that they feel they need to wear sanitary pads or tampons throughout their cycle. First of all, it's unwise to wear such protection continually, so please don't. Seemingly excessive discharge can happen when there are mucus producing cells from the endocervical canal on the cervix; more mucus is produced, which in turn contributes to increased discharge. Unfortunately, we do not have a good way to improve this annoying situation. If cultures for herpes, chlamydia, and gonorrhea—organisms that can infect the columnal epithelial cells of the cervical canal—are negative, if other parts of the evaluation show no abnormal findings, and if future pregnancy is desired, destroying the cells with heat or freezing may eliminate the excess mucus, which can impair fertility. But if testing has shown that the mucus or discharge is normal, women of childbearing age who experience this problem are best advised to put up with the wetness." [1]

How Discharge Changes

This table shows the relationship between the menstrual cycle hormones and secretions.

Cycle Day

Estrogen

Progesterone

Secretions

1-7
Low

Very low

Menstrual flow begins and ends
Few secretions
Dryness

8-13
Rises and peaks

Very low

Secretions increase

14-16
Drops sharply

Starts to rise

Ovulation; maximum clear mucus

17-25
Second small rise

Peaks

Secretions thicken and turn yellowish

26-1
Drops Slowly

Drops rapidly

Secretions diminish to low point

The V Book: A Doctor's Guide to Complete Vulvovaginal Health
by Elizabeth G. Stewart, M.D. Copyright 2002.

Amount of Vaginal Fluid Throughout Menstrual Cycle [1]:

Average: 1.6 grams per eight hour period (1 gram equals 1/4 teaspoon)
Maximum: Day 14 Ovulation - 1.96 grams (almost 1/2 a teaspoon)
Minimum: Days 7 and 26 - 1.4 grams

Women on birth control pills experience less change in the amount of fluid produced, as a result of the pill regulating their hormone levels.

Normal Vaginal and Vulvar Fluids

Sebum: Produced by the oil (sebaceous) glands of the vulva.

Sexual Lubrication: In greatly varying amounts

Left Unaroused - Right Sexually Aroused
http://en.wikipedia.org/wiki/Vaginal_lubrication

From Cervix:

http://www.beautifulcervix.com/

Menstrual:

Menstruation

Sensitivity to Sexual Stimulation

The reported sensitivity of a woman's vagina depends on factors like how the question is phrased and the method and context of the stimulation.

When asked if they are satisfied with the sensitivity of their vagina, 67-75% of women indicate they are satisfied and 25-33% are dissatisfied. (1 out of 3 to 4 women is dissatisfied) Source 1 Source 2

When asked if they are satisfied with the sensitivity of their body during penile-vaginal intercourse, 85-87% of women indicate they are satisfied, and 13-15% are dissatisfied. (1 out of 7 to 8 women is dissatisfied) Source 1 Source 2

On a scale of 0 to 10:

On average, when inserting a tampon women indicate the level of sensation is 4.7.

On average, when asked how much sensation they experience when inserting their own fingers into their vagina, one finger scores 5.4, two fingers 6.5, and three fingers 7.3.

On average, when asked how much sensation they experience when their partner inserts their fingers into their vagina, one finger scores 6.5, two fingers 7.6, and three fingers 8.4.

When their partner inserts their penis into their vagina they indicate an average level of sensation of 8.3. Source

When asked how sensitive their vagina is in comparison to other women, 33% believe their vagina is more sensitive, 38% believe it is equally sensitive, and 11% (1 out of 10) believe it is less sensitive. Source

When asked, "Based on your experiences, do you believe, the vagina is being presented by the media (news, mainstream movies, and magazines) as being more sensitive to stimulation than it actually is?" 52% of women agree and 15% disagree with the statement. Source

When asked, "Based on your experiences, do you believe, the vagina is being presented by the adult entertainment industry (erotica and adult magazines and movies) as being more sensitive to stimulation than it actually is?" 66% of women agree and 11% disagree with the statement. Source

70% indicate they have a G-Spot with varying degrees of distinction (22% very distinct, 32% distinct, 16% barely noticeable). Source

Additional information concerning vaginal sensitivity is available in the article about anal sex.

The outcome of that sexual stimulation varies from woman to woman as well.

On average, when their partner stimulates only their vagina, 5-7% indicate their level of sexual arousal decreases, 20-26% indicates it remains the same, and 69-73% indicate it increases. 27-30% (1 out of 3 to 4) do not experience an increase in their level of arousal. Source 1 Source 2

On average, when their partner stimulates only their vagina with their fingers they experience orgasm 40% of the time, or 2 out of 5 times. Source

During penile-vaginal intercourse, 5% indicate their level of sexual arousal decreases, 14-22% indicates it remains the same, and 73-81% indicate it increases. 19-27% (1 out of 4 to 5) do not experience an increase in their level of arousal. Source 1 Source 2

During penile-vaginal intercourse, without additional forms of sexual stimulation, women experience orgasm 36-39% of the time on average, or 2 out of every 5 experiences. 28-30% or 1 out of 3 to 4 never experiences orgasm without additional forms of stimulation. Source 1 Source 2

Women experience female ejaculation at varying degrees of frequency.

During sexual arousal 40%

During orgasm 46%.

During masturbation 41%.

With a male partner:

During manual stimulation of their vulva 23%

During cunnilingus 18%

During manual stimulation of vagina with fingers 19%

While being stimulated by a dildo or other object 10%

During penile vaginal intercourse 19%

During anal stimulation 4-6%.

With a female partner:

During manual stimulation of their vulva 11%

During cunnilingus 9%

During manual stimulation of vagina with fingers 10%

While being stimulated by a dildo or other object 8%

During anal stimulation 3-4%.

Source 1 Source 2 Source 3

Anatomy Index

Notes:

1) Oral Contraceptives (OC) can be used to inhibit menstruation. At this time, this is believed to decrease the risk of pelvic infections, perhaps because OC's alter the cervical mucus. The cervical mucous likely acts as a barrier to harmful organisms. Reference 1, Reference 2, Reference 3, Reference 4

2) When writing this article I couldn't find the reference from which I came about my prior claim of a 50% increase in the length of the vagina during sexual arousal. Some references say the vagina lengthens, but they don't usually state by how much. Reference 4 states: "So the exceptional man whose erect penis is eight inches long can still make love to any woman, providing he excites her properly and introduces his organ very slowly. If he does this, her vagina will lengthen by 150 or 200 per cent [1 1/2 to 2 times its normal length] to accommodate him." The vagina may stretch when an object is inserted, but sexual arousal alone doesn't appear to lengthen it by all that much. Reference 1, Reference 2, Reference 3, Reference 4

3) MRI images of living subjects have indicated the pelvic muscles are normally not "bowl" shaped, rather "In a woman with normal pelvic floor function, the levator ani muscle complex in its tonically [normal] contracted state has an intricate three-dimensional structure in which its anterior [front] portion (pubococcygeus and puborectalis) is oriented vertically as a sling around the mid-urethra, vagina, and anorectum and its posterior [rear] portion (the pubococcygeus) has a horizontal upwardly biconvex shape resembling a butterfly wing (Figure 3)." [7] Below, I have enlarged and enhanced the image provided in the cited reference.

4) "At birth, the vagina is 4 cm [1.6 inches] long, lengthens approximately 1 cm [0.4 inches] during early childhood and 8 cm [3.1 inches] during late childhood, and reaches mature length of 10 to 12 cm [4 to 4 3/4 inches] by menarche. The vagina at birth resembles the mature vagina with its deep cryptic rugae and folds secondary to [as a result of the] maternal estrogenic effect [raised estrogen level]. As maternal estrogen levels fall in the infant within the first few weeks after birth, the vaginal wall becomes dry, thin, nonelastic, and nonrugated. The vagina remains in this quiescent state until the onset of puberty. During early puberty, increased estrogen levels affect the vaginal epithelia [exposed skin surface]. Such pubertal changes can be noted on examination by identification of the more mature dull pink color of the vaginal mucosa [mucus tissue], increased vaginal secretions, and increased vaginal wall flexibility compared with the prepubertal findings of the red translucent mucosa, sparse secretions, and a relatively rigid vaginal wall." From Rudolph's Pediatrics: Edition 21, by Colin D Rudolph, Abraham M Rudolph, Margaret K Hostetter, George Lister, and Norman J Siegel, editors

5) "The close physical proximity of the urethra and the clitoris to the anterior vaginal wall suggests an association between these anatomical structures and sexual function. In fact, the anterior vaginal wall is an active organ, transmitting during intercourse, the effect of penile thrusting in the vagina to the clitoris, by stretching the two ligaments that insert around its base." Measurement of the Thickness of the Urethrovaginal Space in Women with or without Vaginal Orgasm, Journal of Sexual Medicine Volume 5 Issue 3, Pages 610 - 618

"The distal vagina is a structure that is so interrelated with the clitoris that it is a matter of some debate whether the two are are truly separate structures. The same relationship applies to the female urethra. Though in anatomical terms it is possible to dissect one structure fully from the other, the three structures (distal [outer] vagina, clitoris, and urethra) share blood supply and innervation." The Anatomy of the Distal Vagina: Towards Unity, Journal of Sexual Medicine Volume 5 Issue 8, Pages 1883 - 1891

6) In the U.S. it is illegal for anyone to take a photograph of the vulva or vagina of anyone under the age of 18, and this includes the woman herself. Unfortunately, electronic images are easy to distribute, which means they are potentially a matter of public record once created, especially if a computer or cell phone is lost or stolen, or the images are voluntarily shared with a friend or sexual partner who later shares them with third-parties, which is a common occurrence. At present, our legal system does not make a distinction between appropriate and inappropriate use of technology by those not yet considered an adult by the legal system, hence everything is considered illegal. For women 18 and older, they may want to password protect these images by using encryption software, some of which is available for free. Obviously, the password should be known only to the woman herself, as sharing the password defeats the purpose of having one, and easy to remember ten or more years later.

7) I do not want to appear as though I support male circumcision without reservation, as men were around for thousands of years prior to the invention of circumcision, yet we still survived and evolved as a species; other mammals appear to exist quite well with intact foreskins. Circumcision DOES reduce the rate of HIV transmission, but the primary risk factor isn't associated with a penis having an intact foreskin, but rather with having multiple sexual partners, as well as other risk factors. If a man with an intact foreskin never engages in penile-vaginal or penile-anal intercourse, and other risky activities, then he will more than likely never acquire HIV. The greater the number of sexual partners he has, and the poorer his personal hygiene habits, the greater his risk for acquiring HIV and other STDs, and spreading it to his sexual partners. Circumcision reduces but DOES NOT eliminate the risk of contracting and spreading HIV and other STDs. My concern is that men who are circumcised may believe they are immune to HIV, which is absolutely not true. The same principle applies to young women, and eventually young men, who get the HPV vaccine; getting vaccinated does not eliminate all the other risks factors, only potentially blinds us too them. Strictly and ideally, from a medical perspective, men and women should limit the number of sexual partners they exchange body fluids with to those the plan to conceive a baby with, or at least as few as possible, to protect their overall health and quality of living. This is because harmful organisms are constantly evolving, and the speed at which they spread around the world has reduced from years to hours. This however does not rule out the possibility for engaging in partnered sex with more than one person during your lifetime.

General References:

The V Book: A Doctor's Guide to Complete Vulvovaginal Health, Elizabeth G. Stewart, M.D..

Contemporary Views on Female Pelvic Anatomy, Matthew D. Barber MD

Female Pelvic Floor Anatomy: The Pelvic Floor, Supporting Structures, and Pelvic Organs, Sender Herschorn, MD, FRCSC

Female Genital Anatomy, Center for Sexual Medicine at Boston University School of Medicine

Atlas of Human Sex Anatomy, Robert Latou Dickinson M.D., F.A.C.S.,Copyright 1949 The Williams & Wilkins Company.

A New View of a Woman's Body, The Federation of Feminist Women's Health Centers, Illustrated By: Suzann Gage, L Ac, RNC, NP

Clinically Oriented Anatomy: Fifth Edition, Lippincott Williams & Wilkins.

Eve's Secrets, Josephine Lowndes Sevely.

Cited References:

1. The V Book: A Doctor's Guide to Complete Vulvovaginal Health by Elizabeth G. Stewart, M.D. Copyright 2002.
2. Vaginal Anatomy and Physiology, Siddique, Sohail A. MD, Journal of Pelvic Medicine and Surgery: November/December 2003 - Volume 9 - Issue 6 - pp 263-272
3. Atlas of Human Sex Anatomy, Robert Latou Dickinson M.D., F.A.C.S., Copyright 1949 The Williams & Wilkins Company.
4. Human penis size, Wikipedia.com
5. Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal, Willibrord Weijmar Schultz, Pek van Andel, Ida Sabelis, Eduard Mooyaart
6. Female Genital Anatomy, Center for Sexual Medicine at Boston University School of Medicine
7. Contemporary Views on Female Pelvic Anatomy, Matthew D. Barber MD

How Discharge Changes		This table shows the relationship between the menstrual cycle hormones and secretions.
Cycle Day	Estrogen	Progesterone	Secretions
1-7	Low	Very low	Menstrual flow begins and ends Few secretions Dryness
8-13	Rises and peaks	Very low	Secretions increase
14-16	Drops sharply	Starts to rise	Ovulation; maximum clear mucus
17-25	Second small rise	Peaks	Secretions thicken and turn yellowish
26-1	Drops Slowly	Drops rapidly	Secretions diminish to low point