In the male perineum, rupture of the bulbar urethra (from a straddle injury) causes extravasation of urine. Urine collects in the superficial perineal pouch and tracks into which anatomical spaces?

• A Scrotum and penis, and onto the anterior abdominal wall deep to Scarpa's fascia — but NOT into the thighs (due to Colles' fascia attachment to ischiopubic rami) ✓
• B Ischioanal fossa bilaterally
• C Deep perineal pouch and pelvis
• D Thighs freely, following the deep fascia of the thigh

Explanation

The superficial perineal pouch is bounded inferiorly by Colles' fascia (perineal membrane of skin), which is continuous with Scarpa's fascia of the anterior abdominal wall and Dartos fascia of the scrotum/penis. Extravasated urine/blood spreads within this fascial plane into the scrotum, penis, and up onto the anterior abdominal wall deep to Scarpa's fascia. Crucially, Colles' fascia attaches laterally to the ischiopubic rami, preventing spread into the thighs. The posterior attachment of Colles' fascia to the perineal body blocks posterior spread into the ischioanal fossa.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.