Corpus cavernosum (also cavernous body or erectile tissue; Japanese: 海綿体, kaimentai) is the collective name for the spongy erectile tissue of the penis and clitoris. It is built of vascular sinuses (fine spaces that store blood) enclosed in dense connective tissue; during sexual arousal arterial blood rushes in, the tissue swells and stiffens, and erection results.

Erectile structure of the penis

Three erectile bodies run lengthwise inside the penis. The paired corpora cavernosa penis are two cylindrical structures on the dorsal side that carry the bulk of the erection. Each is wrapped in the tunica albuginea, a tough fibrous sheath that limits expansion when filled with blood and so stiffens the penis. The single corpus spongiosum runs along the ventral midline, surrounding the urethra; its tip expands as the glans and covers the ends of the cavernosa. The spongiosum is kept at lower pressure than the cavernosa during erection, so the urethra is not occluded during ejaculation.

The neural mechanism of erection: sexual stimulation activates the parasympathetic system, releasing nitric oxide (NO), which relaxes the cavernous smooth muscle. The helicine arteries dilate and blood floods the cavernous sinuses, while venous outflow is restricted (the veno-occlusive mechanism), raising intracavernous pressure and completing the erection. PDE5 inhibitors (sildenafil, vardenafil, and others) promote erection by amplifying this NO signalling pathway.

Erectile tissue of the clitoris

The clitoris also has erectile tissue homologous to that of the penis. Long neglected in medicine and anatomy, its true size and the extent of its erectile tissue were first described in detail by the Australian urologist Helen O’Connell and colleagues in 1998 using MRI.

The clitoral bodies (corpora cavernosa clitoridis) form two erectile columns within the visible clitoral glans, continuing into the crura clitoridis that spread laterally along the pubic arch. The vestibular bulbs, located on either side of the vaginal opening, are continuous with this erectile tissue. The whole clitoris reaches 7–12 cm in length, with only a small part exposed at the surface. During arousal the clitoral erectile tissue also fills with blood, swelling and engorging the glans and raising sensitivity. This clitoral erection corresponds to penile erection and is a core process of the sexual response leading to orgasm.

Erectile tissue and sexual dysfunction

Dysfunction of the erectile tissue is a direct cause of erectile dysfunction. When ageing, diabetes, hypertension, or smoking causes fibrosis of the cavernous smooth muscle, the relaxation response declines and filling becomes insufficient. Arteriosclerotic narrowing of the cavernous arteries reduces inflow, and the combination is the principal mechanism of organic erectile dysfunction. Trauma to the perineum or pelvis (including chronic compression from a bicycle saddle) can also impair cavernous blood flow. Radical prostatectomy carries a risk of injury to the cavernous nerves, making preservation of postoperative erectile function a surgical priority.

Peyronie’s disease

Peyronie’s disease is a condition in which fibrous plaque forms in the tunica albuginea of the corpus cavernosum, causing penile curvature, pain, and shortening during erection. The cause remains largely unknown, but repeated microtrauma to the erectile tissue is thought to contribute. Treatment options include oral medication, local collagenase injection, and surgery.

Related terms

• Erection
• Penis
• Clitoris
• Erectile dysfunction