Question

The detrusor muscle of the bladder (is smooth muscle found in the wall of the bladder. The detrusor muscle remains relaxed to allow the bladder to store urine, and contracts during urination to release urine) is predominantly controlled by autonomic fibres with a spinal root value of:

Answer 1

The detrusor muscle of the bladder, which is crucial for urination, is mainly controlled by autonomic fibers originating from the sacral nerves (S2-S4). It remains relaxed during bladder filling due to sympathetic suppression and contracts due to parasympathetic activation during bladder emptying.

Step-by-step explanation:

The detrusor muscle of the bladder plays an essential role in urination. It is predominantly controlled by autonomic fibers that originate from the sacral region of the spinal cord, specifically from the S2 to S4 levels. During the urine storage phase, sympathetic nervous activity via the hypogastric nerves suppresses the contraction of the detrusor muscle. As the bladder fills and stretches, afferent signals travel over the sacral pelvic nerves and activate parasympathetic neurons. This activates efferent neurons to release acetylcholine at the neuromuscular junctions, leading to the contraction of the detrusor muscle and the relaxation of the internal urethral sphincter, thus allowing bladder emptying.

The detrusor muscle of the bladder is predominantly controlled by the autonomic nervous system. Specifically, the parasympathetic division of the autonomic nervous system, which arises from the sacral region of the spinal cord, is responsible for stimulating the contraction of the detrusor muscle during urination. This leads to the expulsion of urine from the bladder into the urethra.