Atlas of Human Anatomy by Netter

FACTS & HINTS

High-Yield Facts

Clinical Points

Micturition

The bladder has a capacity of 400 to 500 mL

During micturition coordinated reflexive contraction of the detrusor and relaxation of the external urethral sphincter occur

Controlled by autonomic and visceral innervation

Visceral afferent fibers traveling along tract of parasympathetic fibers stimulated by stretching (and pain in lower bladder)

Parasympathetic innervation via pelvic splanchnic nerves and pelvic plexus reflexively stimulates detrusor contraction during

micturition.

Sympathetic fibers via hypogastric plexus to bladder neck relaxes bladder neck (internal urethral sphincter) and prevents retrograde

ejaculation during micturition in males

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Clinical Points

Fractures of the Pelvis and Bladder Injury

The bladder lies immediately posterior to the pubic symphysis and fractures of the pubis can be complicated by rupture of the bladder.

The rupture can result in the extravasation of urine intraperitoneally if the peritoneum is torn

Urinary Tract Infections (UTIs)

As a result of a shorter urethra, women are more susceptible to UTIs

Commonly occurs in women following sexual intercourse

Pathogen is commonly Escherichia coli

Infection may lead to urethritis, cystitis, or pyelonephritis (inflammation of urethra, bladder, and kidneys, respectively).

Symptoms include: dysuria, urgency, frequency, and occasionally hematuria

Urinary Stress Incontinence

Factors maintaining continence in the female are the external urethral sphincter (striated muscle surrounding middle third of urethra) and

support of the bladder and urethra by the levator ani muscles

Urinary stress incontinence is an involuntary loss of urine that occurs during coughing, sneezing, laughing, lifting, or exercise, because of

the inability of these muscles to counter the increase in intra-abdominal pressure.

Urinary stress incontinence is often seen in women who have had multiple pregnancies and vaginal childbirths and in men following

prostate surgery

About 50% of all women have occasional urinary incontinence

Mnemonics

Memory Aids

"Water under the bridge" -denotes relationship of ureter (water) to uterine artery, as it passes under the artery.