The Surprising Anatomical Similarities Between Penises and Clitorises

The Surprising Anatomical Similarities Between Penises and Clitorises

These facts about genital anatomy are bound to shock you.

As a society, we're perfectly fine talking about every single body part other than the penis and the vulva-vaginal region. Just look at the language we use — and don't. We teach kids that an elbow is an elbow. A knee is a knee. But when it comes to our genitals, we use words like "hoo-ha" or "wee-wee" to describe a vulva or a penis. (Clearly, our sex ed needs some work.)

That considered, it's not particularly shocking that most people wouldn't be aware of the similarities between female and male genital anatomies. Did you know the clitoris and penis are virtually identical (in scientific terms, homologous, meaning they provide similar functions)?

No? You're not alone. Here's everything you need to know about the anatomical similarities between the cisgender-female and cisgender-male sexual organs. Prepare for your mind to be blown.

First: Genitals do not determine gender identity.

Before hopping into those sizzling facts about clits and penises, it's important to note that the genitals you're born with do not determine your gender. Just because you have a clitoris does not automatically make you a woman and having a penis does not mean you must be a man. Genitals determine your biological sex, whereas gender is the expression or identity that you assume, which falls on a spectrum. These two things, while often related, are not one and the same.

What's more, not every single person has male or female genitals. Some people are born with some combination of both male and female genitals, which is commonly called intersex. Again, being intersex doesn't automatically define you as a man, or a woman, or genderqueer, or any other identity. (Related: LGBTQ+ Glossary of Gender and Sexuality Definitions Allies Should Know)

The issues of sex and gender go far beyond the scope of this article. The aim here is to demonstrate that there isn't some binary distinction that determines whether a human is male or female. We are all, at the end of the day, human beings. Men are from Mars and women are from Venus? More like humans are from Earth and we need to get a clue.

1. Everyone starts the same in utero.

What determines whether you're born cis-male or cis-female are your XX or XY sex chromosomes. The XX pair is cis-female and the XY pair is cis-male. During gestation (the time between conception and birth), the genes on the sex chromosomes are expressed and the fetus becomes cis-male, cis-female, or (in some instances) intersex. These sexual differences are expressed as the penis and testes (cis-male), the vulva and vagina (cis-female), or some combination of the two structures (intersex).

However, in the first six weeks of a pregnancy, before the genes in these chromosomes are expressed, all budding fetuses actually begin as cis-female, meaning that everyone begins their development in the womb with a clitoris. (Wow, right?!) Then, one of two things happens due to "a low level of the hormone testosterone [being] released," this structure grows into a penis, says Laurie Mintz, Ph.D. licensed psychologist, certified sex therapist and author of Becoming Cliterate. Or "when testosterone is absent, the tissues develop into a vulva (including the clitoris) and vagina."

One way to think of it: "The clitoris is the template and the penis is the mutation," explains Cyndi Darnell, sex and relationship therapist and certified clinical sexologist. "All embryos start with a small tissue nub of nerves that is the same. The penis moves outside the body while the clitoris remains within."

2. The penis is external and the clitoris is internal — but they're remarkably similar.

When the XY and XX chromosomes come into play during pregnancy, the fetuses branch off into the cis-male and cis-female categories. The clitoris then grows internally, while the penis grows externally. The differences between these organs may seem big — the penis is a key part of the male reproductive system, whereas the clitoris's only function is pleasure; the clitoris appears to be much smaller than the penis; the clitoris does not contain a urethral canal — however, in reality, they're really quite similar.

"They're simply positioned and shaped differently to accommodate their function and the placement of other internal and external organs around them," says Anne-Hodder Ship, A.C.S., a certified sex educator and founder of Everyone Deserves Sex Ed.

Note: When exploring the genitals, it's important to use the right language. People tend to use 'vagina' as a blanket term when they're really talking about the clitoris and entire outer vulva area, as well as the vaginal canal. The vagina is only the opening that leads from the mouth of the vagina to the cervix. Everything else — on the outside — is called the vulva. (See: 7 Things You Probably Don't Know About Your Vulva, But Should)

While the vast majority of the penis remains on the outside of the body, the clitoris extends inside, down the labia, and back toward the anus. Some internal clitorises (albeit the largest among them) can reach up to 5 inches, the size of the average male penis. This leads to the next mind-blowing fact....

3. Many parts of the clitoris align with the parts of the penis.

"Both the clitoris and the penis function similarly as sensory organs," says Mintz. In a sexual sense, this means they're both sensitive to touch, arousal, and have the ability to give you lots of orgasms.

What's more, both sex organs have corresponding regions. For example, the head of the penis is homologous to the glans clitoris (the nub where the top of inner labia meet, the visible head of the clitoris), with the foreskin and clitoral hood being related in a similar way.

The male scrotum originally starts life as the outer labia of the fetus in utero: "In male fetuses, what starts as the outer lips are then fused to make the sack that encases the balls. In female fetuses, the opening between the lips remains and they fill with fat," explains Mintz. The skin and shaft of the penis are similarly homologous to the inner labia and clitoral shaft, respectively.

Finally, the bulb of the penis (the bundle of tissue that forms a visible ridge at the bottom of the shaft) corresponds with the clitoral/ vestibular bulbs (two structures formed from spongy tissue that extend inside the body, toward the urethra and vagina on the inside edge of the crus of the clitoris). The crus or "legs" of the penis (which are just inside the body, below the bulb) is formed from the clitoral legs (which sit alongside the vestibular bulbs, extending down long the vaginal opening, inside of the body).

Here's the breakdown, quick and dirty:

  • Glans clitoris = head of the penis

  • Clitoral hood = foreskin

  • Outer lips (outer labia) = scrotum

  • Inner lips (inner labia) = skin of the penis

  • Shaft of the clitoris = shaft of the penis

  • Clitoral bulbs (part of internal clitoris, vestibular bulbs) = bulb of penis

  • Clitoral legs (part of internal clitoris, crus) = crus of penis

4. Everyone gets hard-ons.

"All genitals become aroused, and arousal means blood flow. Blood flow is what creates erections in all tissue — be it clitoral or penis — and is essential to enhancing pleasure," explains Darnell. Both the clitoris and penis contain erectile tissue (which is highly sensitive and contains cavernous spaces in the tissue, making it capable of hardening when engorged with blood). The clitoris becomes engorged with blood in much the same way that a penis becomes erect. When blood flows into either the clitoris and penis, it makes them hard (aka erect), says Mintz. That's right: Everyone is out here getting hard-ons.

If you want to learn more about this in in-depth detail, check out Cyndi Darnell's video series, The Atlas of Erotic Anatomy & Arousal. (Even I, a certified sex educator, walked away with my eyes popping out of my head.)

5. It's not easier to orgasm just because you own a penis.

Both penis- and clitoris-owners experience pleasure from touching, licking, sucking, and vibration. While every human is different and enjoys different kinds of stimulation, the commonly held idea that males find it easier to reach orgasm than females is a myth born out of a lack of proper understanding of anatomy. The clitoris has nearly 8,000 nerve endings (twice that of the penis!), and is just as capable of providing pleasure as the penis.

The truth is, everyone likes getting off, regardless of the genitals you possess. "All sets of genitals require arousal for sensation and most genitals appreciate being touched in a variety of ways from soft to rough, with consistent rhythmic stimulation, with and without lube," says Darnell.

One thing's for sure: If young people were given better education about sex, pleasure, and the human body — including how surprisingly awesome all our anatomy is — we'd probably all be having way better sex.

Gigi Engle, A.C.S., is a certified sex educator and author of All The F*cking Mistakes, A Guide to Sex, Love, and Life.