Which of the muscle dysfunction results in Urinary retention?

RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Medical Surgical Nursing

Easy

Appeared in: RRB Nsg. Superintendent -29 April-2025 (shift-2nd)

Explanation

The detrusor muscle is the smooth muscle of the bladder wall responsible for contraction and expulsion of urine.
Micturition (urination) occurs when the parasympathetic nervous system stimulates the detrusor muscle to contract and the urinary sphincter to relax.
Dysfunction, such as weakness or atony (lack of tone) of the detrusor muscle, prevents the bladder from contracting effectively, leading to an inability to empty the bladder, which is known as urinary retention.
This condition is often termed an 'atonic' or 'flaccid' bladder.

Option A: The levator ani is a key muscle of the pelvic floor that supports pelvic organs and maintains continence. Its dysfunction typically causes stress urinary incontinence (leakage with coughing or sneezing) or pelvic organ prolapse, not retention.
Option B: The dartos muscle is a smooth muscle layer within the scrotum of males. Its function is to wrinkle the scrotal skin to help regulate the temperature of the testes. It has no function related to the urinary system.
Option D: The cremaster muscle is responsible for raising and lowering the testes in response to temperature changes and stimulation (cremasteric reflex). It is part of the spermatic cord and plays no role in urination.

Visual 1: Diagram - An illustration of the male and female urinary bladder, highlighting the detrusor muscle, trigone, and internal/external sphincters. This helps visualize the primary muscle involved in bladder emptying.
Visual 2: Flowchart - A simple flowchart showing the neural pathway for normal micturition, from bladder filling to detrusor contraction and sphincter relaxation. This clarifies the process that fails in urinary retention.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pathophysiology of Urinary Retention as background academic context rather than a clinical decision trigger.
Urinary retention is a common clinical problem, especially in postoperative patients (due to anesthesia/analgesics) and older men with benign prostatic hyperplasia (BPH).
A key nursing assessment is to check for a distended bladder by palpation above the symphysis pubis and to use a bladder scanner to measure post-void residual (PVR) volume. A high PVR confirms retention.
Untreated urinary retention can lead to serious complications, including urinary tract infections (UTIs), bladder damage, and acute kidney injury from hydronephrosis (backflow of urine to the kidneys).

How to Approach the Question

First, identify the key concepts in the question: 'muscle dysfunction' and 'urinary retention'.
The question asks which muscle, when malfunctioning, causes the inability to urinate.
Review the function of each muscle listed in the options.
Recall the process of micturition (urination). The bladder must contract to expel urine.
Relate the function of each muscle to this process. The detrusor muscle is the primary muscle of bladder contraction.
Eliminate the other options by identifying their primary functions (pelvic support for levator ani; testicular thermoregulation for dartos and cremaster). This leaves the detrusor muscle as the only logical answer.

Concept Tested & Keywords

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