The clitoris is a sexual organ located at the top of the vulva, and its primary function is pleasure. What most people think of as “the clitoris” is actually just the visible tip of a much larger structure that extends inside the body. The full organ is shaped roughly like a wishbone, with internal branches that surround the vaginal canal.
External and Internal Structure
The part you can see and touch is called the glans. It sits at the top of the vulva, above the urethral opening, and is typically about 6 millimeters long and 5 millimeters wide, though sizes vary widely from person to person. A fold of skin called the clitoral hood covers most of the glans, similar to how foreskin covers the head of a penis. The hood can slide back to expose the glans directly, and it comes in different shapes: rounded like an arch, pointed, or ridged. It protects the highly sensitive tissue underneath from constant friction.
Behind and below the glans is the body of the clitoris, averaging about 25 millimeters long. From there, the structure splits into two legs called crura that extend deeper into the pelvis, each averaging around 52 millimeters. These legs surround the vaginal canal and urethra on both sides. Between the crura and the vaginal wall sit two bulbs of tissue, also about 52 millimeters long each. So while the visible part is small, the full clitoris spans several inches inside the body.
This internal anatomy wasn’t well understood until relatively recently. In 1998, Australian urologist Dr. Helen O’Connell mapped the entire clitoris and its nerve pathways through detailed dissections. She followed up in 2005 with MRI scans that traced blood flow through the organ, revealing its full size and complexity. Before her work, medical textbooks often depicted the clitoris as little more than its external tip.
Why It’s So Sensitive
The clitoris is the most nerve-dense structure in the human body. A 2022 study from Oregon Health & Science University counted the nerve fibers running through the clitoral dorsal nerve (the main nerve supplying the glans) and found over 10,000 fibers. That’s about 20% more than the commonly cited figure of 8,000, which was originally estimated from animal studies. And because the clitoris has additional smaller nerves beyond the dorsal nerve, the true total is even higher.
For comparison, the glans of the penis has a similar type of nerve supply but is spread across a much larger surface area. The concentration of nerve endings in such a small structure is what makes the clitoris extraordinarily responsive to touch.
What Happens During Arousal
When arousal begins, blood flow to the clitoris increases significantly. Arteries feeding the organ dilate, pressure builds inside the tissue, and the glans swells and becomes more prominent. The internal bulbs can double in size as they fill with blood. This process is the same basic mechanism as a penile erection, driven by the same type of signaling between nerves and blood vessels.
This increased blood flow also triggers changes beyond the clitoris itself. The vaginal walls produce lubrication as capillary blood flow to the surrounding tissue surges, and the vaginal canal lengthens and widens. These responses happen together as part of a coordinated process, but the clitoris is the central driver of pleasurable sensation throughout.
Its Role in Orgasm
The clitoris is the primary source of orgasm for most women. Because its internal structure wraps around the vaginal canal, stimulation during penetration can indirectly activate clitoral tissue even without direct contact with the glans. What has historically been described as a “vaginal orgasm” likely involves stimulation of the internal portions of the clitoris, particularly the bulbs and crura pressing against the vaginal walls.
Direct stimulation of the glans is the most reliable path to orgasm for the majority of women. Studies consistently find that most women do not reach orgasm from penetration alone, which makes sense given where the densest nerve supply is concentrated.
Normal Variation in Size and Appearance
There’s a wide range of normal when it comes to clitoral anatomy. The visible glans can be as small as 1 millimeter or as large as 21 millimeters. The combined length of the glans and body ranges from 6 to 80 millimeters across different individuals. The clitoral hood also varies considerably: it can be thin or thick, smooth or folded, and it tends to become looser with age, sometimes covering the glans more completely.
These differences are purely anatomical variation and don’t determine sensitivity or sexual function. Nerve density doesn’t scale with size in a straightforward way, so a smaller clitoris isn’t less sensitive than a larger one.
Shared Origins With the Penis
Early in embryonic development, all fetuses have a small structure called the genital tubercle. In the presence of certain hormones, it elongates significantly to form a penis. Without those hormonal signals, it develops into a clitoris. This shared starting point is why the two organs have so much in common: both contain erectile tissue, both engorge with blood during arousal, and both are densely supplied with sensory nerves. The clitoris is not a smaller or lesser version of the penis. They are parallel structures built from the same tissue, each adapted for its role.