Corpora cavernosa !

The corpora cavernosa are the two spongy cylinders along the top of the penis; they fill with blood and make the penis rigid during an erection.

Official name: Corpus cavernosum of penis

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What it is

Two cylinders of spongy erectile tissue along the top of the penis, each in a tough coat (tunica albuginea); at the back they separate as the crura, attached to the pubic arch.

What it does

Fill with blood to make the penis rigid in erection; the tough coat limits their expansion and traps the blood.

Key facts

Where: Paired dorsal erectile cylinders, each in a tunica albuginea, joined by an incomplete septum; behind they diverge as the crura on the ischiopubic rami, covered by ischiocavernosus
Blood supply: Deep (cavernosal) arteries from the internal pudendal artery, through the helicine arteries; drained by emissary veins to the deep dorsal vein
Nerve: Cavernous nerves (parasympathetic, pelvic splanchnic S2–S4) for erection; sympathetic (T11–L2) for detumescence; dorsal nerve of penis (pudendal, S2–S4) for sensation
Function: Rigidity of erection: arterial inflow fills the sinusoids, which press the outflow veins against the tunica (veno-occlusion); Peyronie plaques form in the tunica

Relations

Course: Each crus is fixed to the ischiopubic ramus and perineal membrane under the ischiocavernosus; the crura meet below the pubic symphysis and run side by side along the shaft to end under the glans penis
Superficial: Buck fascia, binding both with the corpus spongiosum, with the deep dorsal vein, dorsal arteries and dorsal nerves on the dorsum; then dartos and skin
Below: Corpus spongiosum with the urethra, in the groove on their underside
Medial: The septum of the penis between the two, incomplete in front so that both fill together
Contents: Deep artery of the penis in the centre of each, among the cavernous sinusoids

How to find it

Each corpus is felt as one of the two firm columns that make up the upper sides of the shaft. Followed backward into the perineum it becomes a crus fixed to the side of the pubic arch, under the ischiocavernosus. A Peyronie plaque is felt as a firm, sometimes tender, area in its wall.

On imaging

Penile Doppler ultrasound after a vasoactive injection measures flow in the deep artery of the penis (arterial insufficiency) and end-diastolic flow (venous leak). Ultrasound or MRI shows a tunica tear in fracture and plaques in Peyronie disease.

Common problems

Erectile dysfunction, often from poor blood flow (linked to diabetes, smoking and heart disease).
Peyronie's disease: a scar in the coat bends the penis.
Priapism: a painful erection lasting more than 4 hours; an emergency.

How it is diagnosed

History and examination; blood tests (glucose, lipids, testosterone); Doppler ultrasound in some cases.

Treatment

Lifestyle changes and medicines (PDE5 inhibitors); other options if these do not work.
Priapism is drained urgently.

Clinical notes

Prolonged ischaemic priapism scars the erectile tissue and leads to permanent erectile dysfunction, which is why it is relieved urgently by aspiration
Penile prostheses are cylinders placed in both corpora cavernosa when other treatments for erectile dysfunction fail
Erectile dysfunction can be an early sign of vascular disease, appearing before heart disease is known

Development

Forms from mesenchyme of the genital tubercle, which androgens from the fetal testis enlarge into the penis; without them the same tissue becomes the corpora of the clitoris.

Test yourself

Think of the answer, then tap the question to see it.

What happens in a penile fracture of the corpus cavernosum?

The tunica albuginea of an erect corpus cavernosum tears, usually during intercourse: a crack, sudden loss of erection and a swollen, bent penis; the urethra is sometimes injured.

How do ischaemic and non-ischaemic priapism differ?

Ischaemic: painful, rigid, dark acidic blood on aspiration, an emergency. Non-ischaemic: high-flow, often after perineal trauma, usually painless.

Why do the glans and corpus spongiosum usually stay soft in priapism?

Only the corpora cavernosa are engorged.

What mechanism traps blood in the corpora cavernosa during erection?

Veno-occlusion: arterial inflow fills the sinusoids, which press the outflow veins against the tunica albuginea.

What is Peyronie disease?

Fibrous plaques in the tunica albuginea of the corpora cavernosa that bend the erect penis toward the plaque and can cause pain and shortening.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): corpus cavernosum penis
Official Spanish (DeCS): Cuerpo cavernoso del pene
English (TA2): Corpus cavernosum of penis
Also called: crus of penis (back end)

Sources: Anatomy, Abdomen and Pelvis, Penis; Anatomy of the Human Body (20th ed.): Surface Markings of the Perineum (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain.

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Representative model, for educational purposes only.