blaasspier

Blaasspier, in Dutch medical terminology, refers to the detrusor muscle, the smooth muscle layer of the urinary bladder wall responsible for bladder contractions during urination. It is the primary muscular component that generates the force needed to expel urine.

Anatomy and structure: The detrusor muscle forms the thick muscular coat of the bladder wall. It consists of smooth muscle fibers arranged in multiple layers (often described as inner longitudinal, middle circular, and outer longitudinal layers) that together provide elasticity and contractile strength. The muscle is supplied with nerves that regulate its activity and is closely associated with the autonomic nervous system and the urinary tract sphincters.

Physiology and neural control: During bladder filling, the detrusor muscle remains relaxed to accommodate urine. As the bladder nears capacity, afferent signaling triggers a reflex contraction of the detrusor muscle to generate micturition, or urination, coordinated with relaxation of the internal and external urethral sphincters. Parasympathetic stimulation (via pelvic nerves) promotes detrusor contraction, while sympathetic input and somatic control modulate relaxation and sphincter tone. Local reflexes and higher brain centers contribute to voluntary initiation or inhibition of urination.

Clinical relevance: Disorders of the detrusor muscle include detrusor overactivity, contributing to urge incontinence, and detrusor underactivity, which can cause urinary retention. Treatments may involve antimuscarinic medications, beta-adrenergic agents, or injections of botulinum toxin to reduce excessive contractions. Detrusor dysfunction can be associated with neurological, metabolic, or age-related changes affecting bladder function.

Etymology and usage: The term blaasspier is commonly used in Dutch-language medical literature. In English-language contexts, the corresponding term is detrusor muscle of the bladder.

See also: urinary bladder, micturition, detrusor muscle, bladder innervation.