urethra

• urethra

  drains the urinary bladder
• Lining the urethra consists of

  mostly pseudostratified columnar epithelium

  transitional epithelium close to the bladder

  Stratified squamous epithelium close to the urethral orifice
• involuntary urethral sphincter

  involuntary bladder-urethra junction

  contracts to open
• External urethral sphincter


  voluntary muscle surrounding urethra as it passes through pelvic floor
• External urethral orifice

  anterior to vaginal opening; posterior to clitoris
• Prostatic urethra (2.5 cm)


  within prostate
• Intermediate part of the urethra (membranous urethra) (2 cm)

  passes through urogenital diaphragm from prostate to beginning of penis
• Spongy urethra (15 cm)

  passes through penis; opens via external urethral orifice