Overview
The urinary bladder (vesica urinaria) has a cranial apex, a body and a neck continuous with the urethra. When empty it lies on the pubis within the pelvic cavity, ventral to the uterus and vagina; when full it extends cranially over the abdominal floor. The ureters enter its dorsal wall obliquely near the neck, so that urine pressure closes their openings and prevents reflux.
Relations and ligaments
- Median ligament: attaches the ventral surface to the floor of the pelvis and abdomen; in the fetus it contains the urachus, which connects the bladder with the umbilical cord.
- Lateral ligaments: their free edge carries the round ligament, the remnant of the umbilical artery.
- Female urethra: short; it opens on the floor of the vagina at the external urethral orifice. Just ventral to it opens the suburethral diverticulum (diverticulum suburethrale), a blind pouch that extends cranially under the urethra.
Clinical relevance
- Catheterisation: a catheter passed blindly tends to enter the suburethral diverticulum. This is avoided by guiding it with a finger placed in the diverticulum to direct it dorsally into the urethral orifice.
- Cystitis and pyelonephritis: infection with Corynebacterium renale and other bacteria ascends from the bladder to the kidneys.
- Enzootic haematuria: long-term intake of bracken fern (Pteridium aquilinum) causes bleeding and tumours in the bladder wall, in which bovine papillomavirus is also involved.
- Bladder eversion or prolapse: an uncommon complication of straining after calving, through the urethra or through a vaginal tear.
- Calf: a patent urachus and navel infections can spread to the apex of the bladder and form abscesses.
- Obstructive urolithiasis: a problem of the male, with its long urethra and sigmoid flexure; in the female it is exceptional.