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Corpus cavernosum

The corpus cavernosum is one of two paired cylindrical erectile tissues in the penis (and clitoris in females). It is essential for penile rigidity and erection. Each corpus cavernosum lies dorsally within the penis, separated by a fibrous septum, and encased by a strong fibrous sheath known as the tunica albuginea.

The corpora cavernosa are supplied by helicine arteries and venous sinusoids that fill during erection. This erectile tissue is central to sexual function and urological health.

Synonyms

  • Cavernous body

  • Corpora cavernosa (plural)

  • Erectile cylinders of penis

Origin, Course, and Structure

  • Origin:

    • Each corpus cavernosum arises posteriorly as a crus of the penis, attached firmly to the ischiopubic rami

  • Course:

    • Both crura unite anteriorly beneath the pubic symphysis, running along the dorsal shaft of the penis

    • They remain paired, separated by the intercavernous septum, but are fused in the midline distally

  • Structure:

    • Surrounded by the tunica albuginea, a thick fibrous capsule that maintains rigidity during erection

    • Internally composed of trabeculae of smooth muscle and connective tissue, enclosing cavernous vascular spaces

    • The vascular spaces communicate with helicine arteries and venules, allowing rapid blood filling

Relations

  • Dorsally: Dorsal vein, dorsal artery, and dorsal nerve of the penis

  • Ventrally: Corpus spongiosum (containing urethra)

  • Posteriorly: Pubic bones via crura

  • Laterally: Ischiopubic rami

Function

  • Forms the main erectile tissue of the penis, responsible for penile rigidity

  • During sexual arousal:

    • Smooth muscle relaxation allows blood filling of cavernous sinusoids

    • Tunica albuginea traps venous outflow, producing erection

  • Plays a role in sexual function, reproduction, and continence (through rigidity aiding penetration)

Clinical Significance

  • Erectile dysfunction (ED): Corpus cavernosum fibrosis, arterial insufficiency, or venous leakage can impair erection

  • Trauma: Penile fractures involve rupture of the tunica albuginea over the corpus cavernosum

  • Priapism: Prolonged painful erection results from abnormal trapping of blood within corpora cavernosa

  • Tumors: Rarely may harbor primary or metastatic lesions

  • Surgical relevance: Critical in penile prosthesis placement and vascular reconstruction procedures

MRI Appearance

T1-weighted images:

  • Corpus cavernosum shows intermediate signal intensity

  • Fat in surrounding tissues is bright, aiding contrast

  • Fibrosis or scarring may appear as low signal areas

T2-weighted images:

  • Corpus cavernosum demonstrates intermediate to high signal due to vascular sinusoids

  • Fibrotic areas appear dark, while edema or pathology may be brighter

STIR (Short Tau Inversion Recovery):

  • Normal corpus shows intermediate to high signal

  • Edema, inflammation, or tumor infiltration appear as bright hyperintense areas

T1 Fat-Sat Post-Contrast:

  • Enhances heterogeneously depending on vascular filling

  • Normal tissue shows moderate uniform enhancement

  • Tumors or areas of inflammation enhance irregularly

3D T2 SPACE / CISS:

  • Corpus cavernosum appears with intermediate to mildly hyperintense signal compared to muscle

  • Surrounding fat and vascular structures appear bright, providing excellent delineation of tunica albuginea and cavernous spaces

CT Appearance

Non-Contrast CT:

  • Appears as soft tissue density cylinders along the penis

  • Hematomas or calcifications within corpus may be seen as hyperdense regions

Post-Contrast CT:

  • Shows vascular enhancement within cavernous tissue

  • Used in evaluation of trauma (penile fracture, vascular injury)

  • Abnormalities such as tumors or infection may show irregular or focal enhancement

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