The Clitoris: What’s Under The Hood?

Andrew Siegel MD 5/7/16

The clitoris is a complex and mysterious organ possessed by all female mammals. Many men (as well as a fair share of women) are clueless (“uncliterate”) about this curious, unique and fascinating structure. The intent of this entry is to provide a primer of useful knowledge so that you can understand what is under the (clitoral) hood, literally and figuratively.  Advances in imaging—especially magnetic resonance (MR)—have provided a much clearer understanding of clitoral anatomy. Whether you are a female or a male, a greater knowledge and appreciation of the anatomy, function and nuances of this special female body part will most certainly prove useful and beneficial. 

Female External Genital Anatomy

The clitoris is part of the vulva, the outer part of the female genitals. The vulva consists of the mons, outer lips, inner lips, vestibule, vaginal opening, urethral opening and the star of the show–the clitoris.

5. vulva 

(Female external genital anatomy, from The Kegel Fix, credit to illustrator Ashley Halsey)

Clitoral Geography: Mountains, Hills and Earthquakes

The vulva is home to some hilly and bumpy terrain that is well worth gaining familiarity with so it can be traversed with finesse. The word mons derives from Latin meaning “mountain” because it is the rounded and prominent fatty tissue overlying the pubic bone. The word clitoris derives from the Greek “kleitoris” meaning “little hill.”

An earthquake is the shaking of the Earth’s surface caused by the sudden release of energy resulting from movements within the earth’s crust that creates seismic waves. If a female orgasm is thought of as an “earthquake,” the clitoris is the “epicenter.” The head of the clitoris—typically only the size of a pea—is an extraordinarily dense bundle of sensory nerve fibers.

 Pleasure (and Reproduction)

The clitoris is central to the female sexual response and sexual climax, the only human organ that exists solely for pleasure, although nature has secondary motives. The clitoris is a vital part of the anatomical design used for nature’s clever “bait and switch” trick, in which the pursuit of a pleasurable activity drives reproduction of the human species and the perpetuation of life. In the mammalian kingdom, if reproduction was not associated with sexual pleasure, how much sexual activity do you think would actually occur?

Male and Female Comparative Genital Anatomy

It might surprise you how remarkably similar the female and male external genitals are. In fact, in the first few weeks of embryonic existence, the external genitals are identical. The female embryo’s external genitals are the “default” model that will remain female in the absence of masculinizing hormones. The female clitoris and the male penis are essentially the same structure, as are the female outer lips and the male scrotum. In fact, there is not much difference in appearance between a very large clitoris and a very small penis.

Although the clitoris is the female equivalent of the penis, it is exclusively a sexual organ, whereas the penis is a urinary, sexual and reproductive organ. Like the penis, the clitoris is largely composed of erectile tissue that upon arousal and stimulation engorges with blood and with increasing stimulation becomes erect. After sexual climax, the clitoris returns to its normal relaxed state.

Interesting trivia: The female spotted hyena, squirrel monkey, lemur, and bearcat all have in common a very large clitoris. When erect, it appears very similar to the male’s penis and is used to demonstrate dominance over other members of their clans. It is referred to as a “pseudo-penis.”

The Tip of the Iceberg, But Far From Frigid

 Most of the clitoris is hidden and internal. Commonly misrepresented as a “bean” or “button,” the external nub is the clitoral head, merely the “tip of the iceberg.” The iceberg metaphor is an apt one in terms of anatomy, but is off target with respect to what a clitoris is—the seat of female genital passion—with its head having a greater concentration of nerve endings than any other body part, a far cry from “ice.”

Clitoral Anatomy

The glans (head) is the external and visible part of the clitoris. It is located just above the opening of the urethra. The remainder of the clitoris is internal and consists of the clitoral shaft (body) and its extensions, known as crura (legs). The prepuce (foreskin), a hood of skin formed by the inner vaginal lips, covers the clitoral shaft.


(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)

The crura are wishbone-shaped and are attached to the pubic arch as it diverges on each side. The shaft and crura contain erectile tissue, consisting of spongy sinuses that become engorged with blood at the time of sexual stimulation, resulting in clitoral engorgement and erection. Beneath the crura on either side of the vaginal opening are the clitoral bulbs, sac-shaped erectile tissues that lie beneath the outer vaginal lips. With sexual stimulation, they become full, plumping and tightening the vaginal opening.

One can think of the crura and bulbs as similar to 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 head above, comparable to the tree’s trunk and branches.

Pelvic Floor Muscles

These important muscles are critical to sexual function in general and clitoral function in particular. They control the voluntary tightening and relaxing of the vagina, increase genital blood flow, support clitoral erection and contract rhythmically at the time of orgasm. Two of the pelvic floor muscles are especially vital to clitoral function: the ischiocavernosus and bulbocavernosus muscles that surround the crura and the bulbs, respectively. They stabilize the deep roots of the clitoris and compress the roots when engaged, increasing genital blood flow and maintaining clitoral erection, since their compressions push blood from the roots back towards the shaft and glans.

3. superficial and deep PFM

(Female pelvic floor muscles, from The Kegel Fix, credit to illustrator Ashley Halsey)

The pelvic floor muscles strongly contribute to the transformation of the clitoris from flaccid to softly swollen to rigid. By compressing the roots of the clitoris, they elevate blood pressure within the clitoris to maintain clitoral swelling and erectile rigidity. At the time of climax, these muscles contract rhythmically, and an orgasm would not be an orgasm without the contribution of these muscles working together with the clitoris.

Interesting trivia: The blood pressure within the clitoris at the time of a clitoral erection is hypertensive (high blood pressure) range, accounting for the rigidity. This is largely on the basis of the contractions of the aforementioned pelvic floor muscles. The only regions of the body where hypertension is desirable are the penis and clitoris.

Sexual Function And The Clitoris

With arousal and sexual stimulation, the clitoral erectile tissue engorges, resulting in clitoral shaft thickening and swelling of the glans. With increasing clitoral stimulation, clitoral retraction occurs, in which the clitoral shaft and glans withdraw from their overhanging position, pulling inwards against the pubic bone.

When a sufficient threshold of sexual stimulation is reached, climax occurs with contraction of the pelvic floor muscles, vagina, urethra, uterus and anus.

The clitoris plays a central role in orgasm for the majority of women and for most, clitoral stimulation is necessary to achieve orgasm. Some women require direct clitoral stimulation, while for others indirect stimulation is sufficient; about 25% are capable of achieving orgasm via vaginal intercourse alone. Vaginal intercourse often results in indirect clitoral stimulation since the crura and bulbs flank the vaginal opening and these inner parts of the clitoris are stimulated with penetrative thrusting.

Interesting trivia: Magnetic resonance studies have shown that a larger clitoral head size and shorter distance from the clitoris to the vagina are correlated with an easier ability to achieve a vaginal orgasm.

There is a clitoral literacy movement that is gaining momentum. Please visit: for more information on the clitoris and this campaign to foster awareness of this curious organ.

Wishing you the best of health,

2014-04-23 20:16:29

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2 Responses to “The Clitoris: What’s Under The Hood?”

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  2. The Female O: What You Need To Know | Our Greatest Wealth Is Health Says:

    […] both clitoral and vaginal stimulation play important roles in achieving sexual climax. However, the clitoris has the greatest density of nerves, is easily accessible and typically responds readily to […]

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