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Structure

Urinary bladder

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The urinary bladder is a hollow muscular reservoir that stores urine and expels it during micturition. Its capacity is commonly quoted as about 400-500 mL, with wide individual variation.

Terminologia Anatomica (Latin): Vesica urinaria · Open in the 3D atlas

Location

In the adult the empty bladder lies in the lesser pelvis behind the pubic symphysis, below the peritoneum. When distended it rises into the abdomen and becomes palpable above the pubis; in infants it is more abdominal.

Structure

It has an apex, body, fundus (base) and neck, with a detrusor muscle in the wall and an inner urothelium. The trigone is the smooth triangle between the two ureteric orifices and the internal urethral orifice. Relations differ by sex: rectum and seminal vesicles behind in men, uterus and vagina behind in women.

Blood supply

Superior and inferior vesical arteries from the internal iliac artery supply the bladder, with additional branches from the obturator and inferior gluteal arteries, and vaginal or uterine branches in women. Veins form the vesical venous plexus draining to the internal iliac veins, and lymph drains mainly to the external and internal iliac nodes.

Innervation

Parasympathetic pelvic splanchnic nerves (S2-S4) cause detrusor contraction and relaxation of the internal sphincter; sympathetic fibres (T10-L2) via the hypogastric plexus favour storage. The external urethral sphincter is somatic, supplied by the pudendal nerve (S2-S4). Stretch afferents run with the pelvic nerves; pain from the dome follows sympathetic afferents.

Function

The bladder stores urine at low pressure during filling and empties by coordinated detrusor contraction with sphincter relaxation, a reflex under pontine micturition centre control and voluntary cortical inhibition.

Clinical correlations

Urinary tract infection (cystitis), bladder outlet obstruction (for example prostatic enlargement) with retention, neurogenic bladder after spinal cord injury and urothelial carcinoma (haematuria as a presenting sign) are common. Suprapubic catheterisation uses the extraperitoneal position of the distended bladder; technique follows local protocol.

Common exam points

  • Trigone: smooth, between the ureteric orifices and the internal urethral orifice.
  • Distended bladder rises above the pubic symphysis and is extraperitoneal anteriorly.
  • Detrusor: parasympathetic S2-S4 (contraction); sympathetic: storage.
  • External sphincter is voluntary (pudendal nerve).
  • Arterial supply from the internal iliac artery (superior and inferior vesical).

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Hall JE, Hall ME. Guyton and Hall Textbook of Medical Physiology. Elsevier, 14th edition (2020) — Tier 3 (textbook)

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