The clitoris is the primary pleasure organ in female anatomy. It’s a complex structure made of erectile tissue and nerves, with most of it hidden inside the body. The small, visible part at the top of the vulva is just the tip of a much larger network that extends internally around the vagina and urethra.
Where the Clitoris Is Located
The external part of the clitoris sits at the top of the vulva, where the inner lips of skin (labia minora) meet. This visible portion is called the glans, and it’s roughly the size of a pea in most people, though size varies. A small hood of skin partially covers it.
But the glans is only a fraction of the full structure. Internally, the clitoris has a shaft that extends upward and then splits into two wing-shaped extensions called crura, which reach back along either side of the vaginal opening. It also includes two bulbs of erectile tissue that partially surround the urethra and vagina. MRI studies led by Australian urologist Helen O’Connell in the early 2000s revealed that these internal structures form a connected tissue cluster, something older anatomy textbooks had either ignored or mislabeled. Her work showed that the clitoris is not a small, isolated button but a substantial organ with an intimate relationship to surrounding structures.
How It Responds During Arousal
The clitoris is made of the same type of erectile tissue found in a penis. During sexual arousal, blood flow to this tissue increases as smooth muscle in the blood vessels relaxes. The internal chambers fill with blood, causing the tissue to swell and stiffen. This engorgement pushes the glans outward slightly, making it more prominent and more sensitive to touch.
The process works through the same chemical signaling used in penile erections. Nerve signals and blood vessel cells release a molecule that relaxes the walls of small arteries feeding the clitoris, allowing more blood in. The entire erectile tissue cluster, including the internal bulbs and crura, participates in this response, not just the visible glans.
Why It’s So Sensitive
The clitoris is the most nerve-dense structure in the vulva. A 2022 study from Oregon Health and Science University counted the nerve fibers in tissue samples and estimated the human clitoris has more than 10,000 nerve fibers in its main nerve bundle alone. The researchers noted this is likely an undercount, since other smaller nerves also feed into the organ. That concentration of nerve endings in such a small area is what makes even light touch intensely perceptible.
Brain imaging studies have confirmed that clitoral stimulation activates a specific region of the sensory cortex, the strip of brain tissue that maps touch from different body parts. For decades, this “body map” in the brain had only been confirmed in men. Functional MRI research showed that stimulation of the clitoris, vagina, and cervix each activate distinct but neighboring zones in the brain, consistent with the fact that they’re served by different nerve pathways.
Its Role in Orgasm
The clitoris is the primary source of orgasm for most people with vulvas. Direct or indirect stimulation of the clitoris, particularly the glans, produces progressively building sensations of pleasure that can lead to climax. While vaginal stimulation can also contribute to orgasm, the internal portions of the clitoris likely play a role there too, since the crura and bulbs sit close to the vaginal walls.
From an evolutionary perspective, the clitoris and orgasm appear to be inherited from an older biological system. In animals like rabbits, cats, and ferrets, the clitoris sits inside the reproductive tract and triggers a hormonal surge during mating that is required for ovulation. Humans release the same hormones during orgasm, but ovulation happens on its own cycle regardless of sexual activity. Research from Yale and the University of Cincinnati tested this theory by giving rabbits a drug known to suppress orgasm in humans and found the treated rabbits ovulated 30% less often. The clitoral orgasm, then, appears to be a holdover from that older reproductive mechanism, preserved even after it stopped being necessary for conception.
How It Develops Before Birth
Early in embryonic development, every fetus has the same undifferentiated tissue between its legs, called the genital tubercle. Around nine weeks of development, this tissue begins to specialize. In the presence of certain hormones, it develops into a penis. Without those hormones, it develops into a clitoris. This shared origin is why the two organs have such similar internal architecture: both contain the same type of erectile tissue, both engorge with blood during arousal, and both have similar nerve and blood vessel arrangements.
The folds of tissue that fuse to form the shaft of the penis in male development remain unfused in female development, instead becoming the inner labia. This parallel structure is the reason surgeons working on genital reconstructive procedures can apply similar anatomical principles regardless of the patient’s sex.
Why Medical Understanding Took So Long
For most of modern medical history, anatomy textbooks depicted the clitoris as little more than the external glans, often without acknowledging its internal structures. The bulbs of erectile tissue were typically drawn as separate structures alongside the vaginal opening rather than recognized as part of the clitoris. Some texts explicitly stated that no relationship existed between the bulbs and the clitoris, a claim that MRI imaging later disproved.
Part of the problem was methodology. Earlier imaging studies captured the pelvis in cross-sections that happened to display the penis well but were poorly suited to the clitoris, which extends in multiple planes. When researchers began using MRI with axial (horizontal) slices, the full shape and extent of the organ became visible for the first time. The result was a significant revision: the clitoris is now understood as an interconnected erectile tissue complex that partially surrounds both the urethra and the vagina, far larger and more anatomically significant than previous generations of medical students were taught.