Urogenital Triangle
Urogenital triangle contains the external genitalia and openings of the urethra and vagina.
The urogenital triangle is the anterior half of the perineum, containing structures related to the urinary and reproductive systems. It extends between the ischial tuberosities and the pubic symphysis and is bordered posteriorly by the line connecting the two ischial tuberosities (which separates it from the anal triangle). This region includes surface openings such as the urethral and vaginal orifices (in females), the base of the penis and scrotum (in males), and underlying muscles, fasciae, and glands important for micturition, reproduction, and support of pelvic organs.
Structure
The urogenital triangle includes superficial and deep compartments, separated by the perineal membrane. It houses erectile tissues, accessory glands, perineal muscles, and external genitalia.
Boundaries
- Anterior: Pubic symphysis
- Lateral: Ischiopubic rami
- Posterior: Line connecting the ischial tuberosities (boundary with anal triangle)
Contents by Layer
1. Superficial perineal pouch (between Colles' fascia and perineal membrane):- Erectile bodies (corpus spongiosum, corpora cavernosa)
- Superficial perineal muscles (ischiocavernosus, bulbospongiosus, superficial transverse perineal muscle)
- Greater vestibular glands (Bartholin's glands) in females
- Deep transverse perineal muscle
- External urethral sphincter
- Compressor urethrae and sphincter urethrovaginalis (in females)
- Bulbourethral glands (Cowper's glands) in males
Fasciae
- Perineal membrane: Dense fibrous sheet forming the floor of the deep perineal pouch
- Colles' fascia: Superficial fascia continuous with Scarpa's fascia of the anterior abdominal wall
Location
The urogenital triangle lies anteriorly in the perineum, inferior to the pelvic diaphragm. It is most easily observed with the thighs abducted and is seen between the pubic symphysis and a line connecting the ischial tuberosities.
| Direction | Related Structures |
|---|---|
| Anterior | Pubic symphysis and mons pubis |
| Posterior | Anal triangle (at ischial tuberosities) |
| Superior (deep) | Pelvic diaphragm |
| Inferior (surface) | Perineal skin and superficial fascia |
Function
- Urinary Outlet Support: Contains the external urethral sphincter and perineal muscles for urethral control
- Sexual Function: Houses erectile tissues and glands essential for sexual arousal and reproduction
- Structural Support: Provides muscular and fascial support to pelvic organs
- Vaginal Function (female): Accommodates vaginal opening, with surrounding musculature aiding in tone and closure
Clinical Significance
- Perineal Tears: Common during childbirth, may involve muscles of the urogenital triangle
- Episiotomy: Surgical incision made in this region to prevent uncontrolled tearing
- Urethral Injury: Trauma to the perineum (e.g., straddle injury) may rupture the spongy urethra
- Infections: Bartholin gland abscesses or perineal abscesses can arise in this region
Last updated on May 11, 2025
