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Core Urology · Penis & UrethraCore Urology / Penis & Urethra

Disorders of the Penis & Male Urethra

This chapter gathers the everyday and the emergent disorders of the penis and male urethra — the foreskin problems (phimosis, paraphimosis), the congenital meatal anomalies (hypospadias, epispadias), urethral strictures, and conditions like Peyronie's disease.

Orientation

The big picture

This chapter gathers the everyday and the emergent disorders of the penis and male urethra — the foreskin problems (phimosis, paraphimosis), the congenital meatal anomalies (hypospadias, epispadias), urethral strictures, and conditions like Peyronie's disease. The thread is recognising which are emergencies (paraphimosis) and which carry longer-term risk (phimosis → cancer; stricture → obstruction).

Golden rule

The framework: foreskin disorders (phimosis vs paraphimosis), congenital meatal anomalies (recap), urethral stricture, and Peyronie's disease.

Pathophysiology

Mechanism pathway

Tap any step to see why it happens.

Illustration

The male urethra — four segments

The male urethra — four segments

From bladder to meatus: prostatic → membranous (where the external sphincter sits) → bulbar → penile (spongy). Knowing the segments explains where strictures, injuries and instrumentation problems occur.

bladder prostate 1 · Prostatic urethra through the prostate; verumontanum (●) on its floor 2 · Membranous urethra shortest; through the striated external sphincter (○) 3 · Bulbar urethra widest point; common site of straddle injury 4 · Penile (spongy) urethra runs in the corpus spongiosum to the meatus
The urethra runs prostatic → membranous → bulbar → penile. The verumontanum sits on the floor of the prostatic urethra (the ejaculatory ducts open here). The membranous segment passes through the striated external sphincter — the key continence mechanism after prostatectomy. The bulbar urethra is the usual site of straddle (perineal) injury, and the penile urethra runs within the corpus spongiosum. Anterior urethra = bulbar + penile; posterior urethra = prostatic + membranous. Grounded in leading urology references.
Illustration

The penis — cross-section

The penis — cross-section (layers from outside in)

Read it from the outside inward: skin → dartos/superficial fascia → Buck's (deep) fascia wrapping all three bodies, then a tunica albuginea around each erectile body. The two dorsal corpora cavernosa do the erecting; the ventral corpus spongiosum carries the urethra.

Dorsal neurovascular bundle deep dorsal vein (blue) + paired dorsal arteries (red) + nerves — 12 o'clock Skin thin, hairless, freely mobile Dartos / superficial (Colles') fascia loose subcutaneous layer beneath the skin Buck's (deep) fascia tough layer that encloses ALL THREE bodies together Tunica albuginea thick fibrous sheath around EACH corpus (brown band) Corpora cavernosa (×2) paired dorsal erectile chambers — the erection Cavernosal (deep) artery runs centrally in each corpus cavernosum Corpus spongiosum + urethra ventral; surrounds the urethra, forms the glans distally
Buck's fascia (encloses all 3) Tunica albuginea (around each) Cavernosal erectile tissue Spongiosum (urethra)
The key distinction this figure makes clear: the tunica albuginea is a thick fibrous sheath wrapped around each individual corpus (the brown bands), whereas Buck's fascia is the outer tough layer that binds all three bodies together (the dark band beneath the dartos and skin). The two corpora cavernosa are the dorsal erectile chambers, each with a central cavernosal artery; the ventral corpus spongiosum carries the urethra and expands distally to form the glans. The dorsal neurovascular bundle — deep dorsal vein, paired dorsal arteries, and dorsal nerves — lies at the 12 o'clock position deep to Buck's fascia. Grounded in leading urology references.
Work-up

Diagnostic algorithm

Each step answers one question. Tap to expand.

Exam

Board traps

Phimosis (can't retract) is a chronic-risk problem (cancer, calculi); paraphimosis (trapped retracted foreskin) is an emergency.

Always reduce/replace a retracted foreskin to prevent paraphimosis.

Hypospadias = ventral (never proximal to bulbous urethra); epispadias = dorsal (with exstrophy).

Straddle injury → bulbar urethral stricture; image with retrograde urethrogram.

Peyronie's = tunica albuginea fibrous plaque → curvature.

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Related topics

HypospadiasUrethral TraumaMale Sexual DysfunctionPenile Cancer
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