The clitoris is a female sex organ. Thanks to a complex network of erectile tissue and nerves, it is the most sensitive female erogenous zone and is important for sexual stimulation and orgasm. The vulva is the outer part of the female genitalia, and includes the clitoris, labia majora, and labia minora. The part of the clitoris visible externally is below the mons pubis, which is a mound of skin atop your pubic bone, and above the external orifice of the urethra, at the junction of the labia minora.
The clitoris in not just a small magic button on the vulva! That small button is just one small part of the clitoris, called the glans clitoris. The glans clitoris is the clitoris’ distal extremity, sandwiched by the prepuce of the clitoris, or clitoral hood, anteriorly and the frenulum of the clitoris posteriorly. The rest of clitoris extends into the pelvic cavity and is shaped like a V. Apart from the glans, the clitoris is composed of erectile tissue, which is tissue that, upon stimulation, fills with blood and swells up.
The section of the clitoris directly behind the glans is called the clitoral body, or shaft. It’s the part that is not divided. These two columns of erectile tissue are each called a corpus cavernosum, and together are called corpora cavernosa. The main body of the corpora cavernosa, together with a ventral erectile strip, make up the shaft, which continues to the glans. The body of the clitoris transitions into the angle of the clitoris, which transitions into the root of the clitoris.
The body branches to form two legs, or two crus - plural crura, and these are the longest part of the clitoris. The crura surround the vaginal canal and urethra. The crura are covered by ischiocavernosus muscles and attach to the ischiopubic rami.
During a clitoral erection, or tumescence, the corpora cavernosa become engorged with blood. This happens because, during sexual arousal, arterial blood flow to the clitoris increases and trabecular smooth muscles of the clitoris’ erectile tissues relax to allow the blood into the vascular spaces of its erectile tissues. The ischiocavernosus and bulbospongiosus contract and compress the dorsal vein, preventing blood draining and so trapping the blood inside the clitoris.
The corpora cavernosa are surrounded by a fibrous sheath called the tunica albuginea. One interesting difference between clitoral and penile erection is that while in the penis, the tunica albuginea has two layers, in the clitoris it has just one. As a result, the tunica albuginea of the clitoris is much stretchier, and when the corpora cavernosa fill with blood, they just become engorged, not stiff like in a penis erection. Another fun fact about clitoral physiology - sometimes during waking and sometimes during sleep, mostly during the REM sleep phase, the clitoris can spontaneously swell, to the same magnitude as during erotic stimulation when awake. This is called nocturnal clitoral tumescence.
It is debated whether the vestibular, or clitoral, bulbs are part of the clitoris. A paired structure, they are found between the crura and the vaginal wall. Their anterior ends are joined together by the pars intermedia, also called the commissure of the vestibular bulbs, while the posterior ends are in contact with the greater vestibular glands. There is a strip of erectile tissue running along the corpora cavernosa main body that connects the glans to the commissure of the vestibular bulbs.
The vestibular bulbs are covered by the bulbospongiosus. The vestibular bulbs are made up of erectile tissue and on arousal, they swell, squeezing the vaginal opening and causing the vulva to expand outwardly. This blood is released back into the circulatory system during orgasmic spasms, or over the course of a few hours if orgasm does not occur. If orgasm does not occur, the person with the vagina may experience an uncomfortable sensation colloquially called “blue vulva”, which involves heaviness and achiness around the genitals. Swelling of the clitoris’ erectile tissue also increases pressure on the vaginal wall and stimulates lubrication. Some scientists think that the vestibular bulbs are actually responsible for G-spot pleasure. The G-spot, is an area a few inches inside the vagina which feels pleasurable upon stimulation. This spot might be pleasurable because that’s where the vestibular bulbs meet the vaginal wall.
Finally, let’s discuss the clitoris’ neurovasculature! In terms of blood vessels, there’s the dorsal artery of the clitoris, the deep artery of clitoris, which is found in the corpora cavernosa, the deep dorsal vein of clitoris and the superficial dorsal vein of clitoris. In terms of nerves, there’s the dorsal nerve of clitoris, which branches off the pudendal nerve, which connects to the S2 to S4 sacral spinal roots. The dorsal vein and artery of the clitoris and the dorsal nerve of the clitoris are sandwiched between the tunica albuginea and the clitoral fascia.