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Septum of the penis (Penile septum)

The septum of the penis is a fibrous partition that separates the two corpora cavernosa, the paired erectile bodies located on the dorsal aspect of the penis. It is incomplete, allowing vascular communication between the two corpora, which is essential for uniform penile erection. Its structure, variations, and pathological changes are significant in urology, and its appearance on imaging is important in evaluating erectile dysfunction, trauma, and fibrosis.

Synonyms

  • Penile septum

  • Corpus cavernosum septum

  • Septum penis

Origin, Structure, and Course

  • Origin: Formed by the fusion of the medial walls of the two corpora cavernosa

  • Structure:

    • Composed of fibrous tissue with trabeculae and vascular spaces

    • Incomplete, perforated by numerous small vascular channels, giving it a fenestrated or mesh-like appearance

    • Thickest proximally near the root of the penis, thinner distally toward the glans

  • Course: Extends longitudinally along the shaft of the penis, separating right and left corpora cavernosa throughout most of their length

Relations

  • Anteriorly: Dorsal penile vessels and nerves (located between tunica albuginea and skin)

  • Posteriorly: Urethra within the corpus spongiosum (ventral to corpora cavernosa)

  • Laterally: Corporal sinusoids of the corpora cavernosa on both sides

  • Superiorly/Inferiorly: Confined within the tunica albuginea of the penis

Function

  • Provides structural support to the penis

  • Maintains separation of the corpora cavernosa while permitting vascular communication

  • Contributes to rigidity and uniformity of erection

  • Assists in distribution of intracavernosal pressure during penile tumescence

Clinical Significance

  • Trauma: Septal tears may occur with penile fracture, usually accompanied by tunica albuginea rupture

  • Fibrosis: Peyronie’s disease may involve septal scarring, leading to penile curvature or erectile dysfunction

  • Imaging relevance: Fenestrated septum explains cross-filling of corpora during cavernosography or duplex Doppler

  • Surgical importance: Recognized in reconstructive and prosthetic penile surgeries

MRI Appearance

T1-weighted images:

  • Septum appears as a thin low-signal intensity line between the corpora cavernosa

  • Surrounded by high-signal fat externally and intermediate-signal erectile tissue internally

T2-weighted images:

  • Appears as a dark hypointense band between the bright vascular sinusoids of the corpora cavernosa

  • Thickening or irregularity may be seen in fibrosis or trauma

STIR (Short Tau Inversion Recovery):

  • Septum remains low signal

  • Surrounding pathology (hematoma, inflammation, fibrosis) appears bright

T1 Fat-Sat Post-Contrast:

  • Septum itself shows no significant enhancement

  • Inflammatory or fibrotic changes may show mild to moderate enhancement

3D T2 SPACE / CISS:

  • Septum appears as a thin hypointense line with clear separation of the two corpora cavernosa

  • Excellent delineation of septal fenestrations and continuity in high-resolution multiplanar views

CT Appearance

Non-Contrast CT:

  • Septum usually not distinctly visualized

  • Seen indirectly as a subtle partition between corpora cavernosa when contrast or hematoma is present

  • Fibrosis or calcification may appear as dense foci along the septum

Post-Contrast CT:

  • Septum itself shows minimal to no enhancement

  • Pathology such as septal hematoma, fibrosis, or neoplastic infiltration may alter appearance with contrast enhancement

MRI image