Posts Tagged ‘vestibule’

V Power: What You Should Know About Lady Parts

March 20, 2021

Andrew Siegel MD    3/20/2021

Many lady parts are “V” words– vulva, vagina, and vestibule–appropriately named since the overall geography is V-shaped. The goal of today’s entry is for the reader to attain a clear understanding of this seemingly simple–but in reality–complex sector of anatomy. No matter your gender, a better understanding and appreciation of the anatomy, function and nuances of these curious female body parts–achieving V-literacy— will be beneficial.

“The vagina is a place of procreative darkness, a sinister place from which blood periodically seeps as if from a wound.”

“Even when made safe, men feared the vagina, already attributed mysterious sexual power – did it not conjure up a man’s organ, absorb it, milk it, spit it out limp?”

–Tom Hickman from God’s Doodle

How well do you know your lady parts?

In all likelihood not too well, since female nether zones are mysterious to many–including, not uncommonly, their owners, who often have limited knowledge of their own inner workings. Understandably, concealed internal anatomy is more difficult to decipher than exposed external anatomy. If women are anatomically not well informed, many men are downright clueless, their concept of the vagina being a curious gash in a female’s body where a penis can be inserted and where babies magically emerge.  

Shrouded in taboo, uncertainty and misunderstanding, this bewildering terrain obscured in the recesses of the female body is a dark and mysterious place. The intricate geography includes three openings, two pairs of lips, mounds, swellings, glands, tissues that engorge, and specialized muscles. Unfortunately, V-parts do not come with topographical maps.

Please take a brief quiz to assess your knowledge of lady parts. See how many of the 8 parts you can properly identify (answers below):

(Thank you Michael Ferig, Wikipedia Commons).

Answers to Anatomy Quiz
LM: labia majora (outer lips); VV: vaginal vestibule; LM: labia minora (inner lips); C: clitoris; U: urethra (urinary channel); V: vagina; H: hymenal ring (remnant of membrane that partially covered vaginal opening); A: anus


The word “vulva” derives from the Latin “cunnus” (hence the derivation of the slang C-word).  External lady terrain is the VULVA, not the VAGINA, as it is commonly referred to. This outside part of the female genitals consists of the mons pubis (pad of fatty tissue that covers pubic bone), labia majora (outer lips), labia minora (inner lips), vestibule (entranceway to urinary channel and vaginal canal), vaginal opening, urethral opening, and clitoris. Vulvas come in many different shapes and sizes, as anatomical variable and unique as penises.

Vulva Collage (public domain)

The mons consists of hair-bearing skin and extends down on each side to form the labia majora, folds of hair-bearing skin and underlying fatty tissue that surround the vaginal opening. Within the labia majora are two soft, hairless skin folds known as labia minora, which safeguard the entrance to the vagina. The upper part of each labia minora unites to form the clitoral hood (prepuce or foreskin) at the upper part of the clitoris and the frenulum (a small band of tissue that secures the clitoral head to the hood) at the underside of the clitoris.


As the vestibule of your home is the entrance hall, so the female vestibule is the external “entryway,” the space located between the inner lips that contains the openings to the vagina (vaginal orifice) and the urethra (urethral meatus).


 Uterus, Cervix and Inner Third Vagina
from Dr. Johannes Sobotta – Sobotta’s Atlas and Text-book of Human Anatomy 1906, note the vaginal rugae and the relationship of the cervix with the inner vagina

The word “vagina” sensibly derives from the Latin word for “sheath,” a cover for the blade of a sword. The vagina is a fibro-muscular tube that connects the cervix to the vestibule.  It is situated below the bladder and above the rectum and is the canal that permits menstruation, penile penetration, ejaculation, insemination, and fertilization as well as the passageway for birth– an extraordinary organ, with capacities that are equal if not more impressive than those of the penis.

The vagina is by no means a passive canal, but a responsive and contractile organ with pleats and folds called rugae that maximize its elasticity and stretchiness. These accordion-like ruffles and ridges supply texture, which increase friction for the penis during sexual intercourse. In a young woman they are prominent, but with aging they tend to disappear.

The average depth of the vagina (without sexual stimulation) is 3-4 inches or so, but with sexual stimulation and arousal, the vagina is capable of considerable expansion (similar to the change in penile anatomy with stimulation and arousal). The elasticity of the vagina is truly impressive, perhaps being the most elastic and stretchable organ in the body with the ability to stretch to accommodate a full-term infant and then return to a relatively normal caliber. The width of the vagina varies throughout its length, narrowest at the vaginal opening and increasing in diameter throughout its depth. It is typically about 1-inch in diameter at the external opening.

Joke from How deep is the average vagina?

Deep enough for a man to lose his house, his car, his dog and half of his savings and assets.

Every vagina is unique and variable in shape, size and even color, similar to variations in penile anatomy. Vaginas are banana-shaped structures and when a woman lies down on her back, the more external part of the vagina (closest to the vaginal opening) is straight, and the inner, deeper part angles/curves downwards towards the sacral bones (the lower part of the vertebral column that forms the back part of the pelvis). This vaginal “axis” often changes with aging and childbirth.

Under normal circumstances, the vagina is no more “primed” or prepared for sex than is a flaccid penis. The un-stimulated vagina is essentially a closed “potential space” in which the vaginal walls are in contact with each other in an “H”-like configuration. With sexual stimulation, the vagina expands with lengthening and widening of its inner two-thirds and flattening of the rugae. The cervix and uterus pull up and back. Pelvic blood flow increases and the vaginal walls undergo a “sweating-like” reaction as a result of pelvic blood congestion, creating a slippery and glistening film. Most vaginal lubrication is based upon this seepage, but some derives from Bartholin’s and Skene’s glands. Bartholin’s glands are paired, pea-size glands that drain just below and to each side of the vagina. During sexual arousal they secrete small drops of fluid, resulting in moistening of the opening of the vagina. Skene’s glands, the female equivalent of the male prostate gland, are paired glands that secrete fluid with arousal and drain just above and to each side of the urethral opening. With sexual excitement and stimulation, the resultant increased pelvic blood flow in addition to being responsible for vaginal congestion and lubrication also brings about congestion and engorgement of the vulva and clitoris.

Fact: The profound vaginal changes that occur during sexual arousal and stimulation are entirely analogous to the changes that occur during male arousal: expansion of penis length and girth, retraction of the testicles towards the groin, and the release of pre-ejaculate fluid.


“Clitoris” derives from the Greek “kleitoris,” meaning “little hill.” If the vagina is considered mysterious, the clitoris is a “riddle, wrapped in a mystery, inside an enigma” (to quote Churchill from a context that was clearly not about female anatomy). 

The clitoris is mostly subterranean–what you see is merely the “tip of the iceberg.”  The white lines indicate the “rest of the iceberg.”
(By Remas 6 [CC0], via Wikimedia Commons)

The clitoris is uniquely an erectile organ that has as its express purpose sexual function, as opposed to the penis, which is a multi-tasking sexual, urinary and reproductive organ. The clitoris plays a vital role in sensation and orgasm and is the center of female sensual focus and the most sensitive erogenous zone of the body. If an orgasm is thought of as an earthquake, the clitoris is the epicenter, the site where most orgasms are triggered. The head of the clitoris, typically only the size of a pea, is a dense bundle of sensory nerve fibers, arguably having a greater nerve density than any other body part.

Like the penis, the clitoris is composed of an external visible part and internal, deeper and more substantial “invisible” parts. The inner parts are known as the crura (legs), which are shaped like a wishbone with each side attached to the pubic arch as it descends and diverges. The visible part is located above the opening of the urethra, near the junction point of the inner lips. Similar to the penis, the clitoris has a glans (head), a shaft (body) and is covered by a hood of tissue that is the female equivalent of the prepuce (foreskin).

Anatomy of the vulva and the clitoris 
by OpenStax College – Anatomy & Physiology, Connexions Web site., Jun 19, 2013., CC BY 3.0,, no changes made to original

A comparison of the penis (left) and clitoris (right)
Esseh, CC BY-SA 3.0 <;, via Wikimedia Commons

Possessing a clitoris may be the closest a woman will ever get to know what it is like to have a penis, as the clitoris is the female version of the penis. However, the clitoris is a subtler and more mysterious organ, a curiosity to many women and men alike. It is similar to the penis in that it becomes engorged and erect when stimulated. Clitorises, like penises, come in all different sizes and shapes. A large clitoris does not appear that much different from a small penis. The average length of the clitoral shaft including the glans is 0.8 inches, ranging from 0.2-1.4 inches.

Female erectile organs in red (3, 4, 5): and purple (6)
1. Suspensory ligament of clitoris; 2. Angle (elbow) of clitoris; 3. Body of clitoris; 4. Glans of clitoris; 5 – Crus of clitoris; 6 – Bulb of vestibule; 7. Inferior pubic ramus; 8. Pubic bone; 9. Superior pubic ramus; 10. Pubic symphysis
Avereanu, CC BY 4.0 <;, via Wikimedia Commons

The clitoral shaft and crura contain the spongy erectile sinus tissue that becomes engorged with blood at the time of sexual stimulation, resulting in clitoral engorgement and erection. The clitoral bulbs are additional erectile tissues that are sac-shaped and are situated between the crura. With sexual stimulation, they become full, plumping and tightening the vaginal opening. One can think of the crura and bulbs in terms of the roots of a tree, hidden from view and extending deeply below the surface, yet fundamental to the support and function of the clitoral shaft and clitoral glans above that can be thought of as the trunk of a tree.

When the clitoris is stimulated, the shaft expands with accompanying swelling of the glans. With increasing stimulation, clitoral retraction occurs, in which the clitoral shaft and glans withdraw from their overhanging position, pulling inwards against the pubic bone. Sexual intercourse results in indirect clitoral stimulation. The clitoral shaft moves rhythmically with penile thrusting by virtue of penile traction on the inner lips, which join together to form the hood of the clitoris. With increasing stimulation and arousal, physical tension within the genitals builds and once intensity and duration of sexual stimulation surpass a threshold, involuntary rhythmic muscular contractions occur of the vagina, uterus, anus and pelvic floor muscles, followed by the release of accumulated erotic tension (a.k.a. orgasm) and a euphoric state. Thereafter, the genital engorgement and congestion subside, muscle relaxation occurs and a peaceful state of physical and emotional bliss and afterglow become apparent.

Pelvic Floor Muscles

During sexual stimulation, the clitoris engorges and erects, aided by two of the superficial pelvic floor muscles—the ischiocavernosus (IC) and bulbocavernosus (BC) muscles—that contract and compress the deep internal portions of the clitoris, (the crura and the bulb, respectively) maintaining blood pressure within the clitoral erection chambers to levels that are significantly higher than systemic blood pressure.

The bulbocavernosus reflex (BCR) is a contraction of the BC and IC muscles (and other pelvic floor muscles, including the anal sphincter) that occurs when the clitoris is stimulated. The BCR is important for maintaining clitoral rigidity, since with each contraction of the BC and IC muscles there is a surge of blood flow to the clitoris, perpetuating clitoral engorgement and erection.

During arousal the pelvic floor muscles also help increase pelvic blood flow, contributing to vaginal lubrication, genital engorgement and the transformation of the clitoris from flaccid to softly swollen to rigidly engorged.  The pelvic floor muscles enable tightening of the vagina at will and at the time of climax, contract rhythmically.  An orgasm would not be an orgasm without the contribution of these important muscles.

Bulbocavernosus muscle
(pelvic floor muscle that supports and compresses the clitoral bulbs)

Ischiocavernosus muscle
(pelvic floor muscle that supports and compresses the clitoral legs)
(Above two images are in public domain, originally from Gray’s Anatomy 1909)

Knowledge is power, and hopefully this review of female genital anatomy and function has provided you with V-power.

Wishing you the best of health,

2014-04-23 20:16:29

A new blog is posted weekly. To receive a free subscription with delivery to your email inbox visit the following link and click on “email subscription”:

Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.  His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. 

4 small

Video trailer for Prostate Cancer 20/20

Preview of Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

PROSTATE CANCER 20/20 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

FINDING YOUR OWN FOUNTAIN OF YOUTH: The Essential Guide to Maximizing Health, Wellness, Fitness and Longevity

PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food

MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health