Detrusorlihas

Detrusorlihas, or the detrusor muscle, is the thick smooth muscle layer that forms the wall of the urinary bladder. Its primary role is to generate the force needed to expel urine during micturition. The detrusor coordinates with sensory signals of bladder filling and the neural commands that trigger urination.

Anatomically, the detrusor consists of smooth muscle fibers arranged in layers within the bladder wall. The three-layer arrangement is often described as inner longitudinal, middle circular, and outer longitudinal fibers. These layers blend with connective tissue and, toward the bladder neck, contribute to the overall contractile behavior necessary for complete bladder emptying.

Autonomic and somatic innervation regulates detrusor activity. Parasympathetic nerves from the pelvic splanchnic system release acetylcholine and act on muscarinic receptors to induce detrusor contraction during voiding. Sympathetic nerves from the hypogastric system promote storage by relaxing the detrusor via beta-adrenergic pathways. Somatic control of the external urethral sphincter, via the pudendal nerve, provides voluntary modulation of urination.

Clinically, detrusor function is central to disorders of bladder storage and emptying. Detrusor overactivity causes urgency and urge incontinence, while detrusor underactivity or acontractile detrusor leads to poor bladder emptying. Neurological injury can produce detrusor-sphincter dyssynergy, complicating coordinated voiding. Urodynamic studies assess detrusor pressure and contractility to diagnose these conditions.