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The detrusor muscle (or detrusor urinae muscle)is the smooth muscle component of the urinary bladder and facilitates contraction of the bladder wall during micturition.
Forms the smooth muscle component of the bladder wall. The urothelial lining overlies it within the bladder cavity. The muscle fibers of the detrusor are organized in a swirl/whorl type pattern to act in unison to provide mass contraction of the bladder 1. The muscle is continuous with the internal urethral sphincter inferiorly, near the bladder neck.
- superior and inferior vesical arteries (from anterior division of internal iliac artery)
- small contribution from obturator, inferior gluteal, uterine and vaginal arteries
- plexus of pelvic veins eventually draining to the internal iliac veins
- parasympathetic (excitatory): pelvic splanchnic nerves (S2–S4)
- sympathetic (inhibitory): superior hypogastric and pelvic plexuses (T10–L2)
The detrusor muscle plays an important role during micturition with its stretch receptors responsible for the sensation of a full bladder and its contraction from efferent parasympathetic impulses responsible for emptying 2. For more informations, see bladder neuroanatomy and the co-ordination of micturition.
Hypertrophic changes of the detrusor muscle due to conditions such as bladder outlet obstruction are visible during cystoscopy and give the bladder a characteristic appearance known as “trabeculation”. This may also be seen on imaging as concentric and irregular bladder wall thickening 3.