URINARY SYSTEM 2 Urinary Bladder and Urethra

Urinary Bladder

Site: It lies in the anterior and lower part of the pelvic cavity. Shape: It is pyramidal in shape. Retroperitoneal organ Lies behind the Symphysis Pubis

It is a collapsible muscular sac Stores and expels urine Full bladder – is spherical and expands into the abdominal cavity Empty bladder – lies entirely within the pelvis

Parts: 1. Apex: Directed anteriorly (Median umbilical ligament) to the umbilicus??? 2. Base: Directed posteriorly.- Trigone 3. Three surfaces: a. Superior surface. b. Two infero-lateral surfaces (one on each side). 4. Three angles: a. Two postero-superior angles (one on each side). b. Inferior angle (neck of the bladder).

Structure: - The bladder wall is formed of the following layers:  1 Structure: - The bladder wall is formed of the following layers:  1. Mucosa: Lined by transitional epithelium. 2. Muscular layer: - It is formed of detrusor muscle. 3. Serosa

The Neck of the bladder is the most fixed part Held in position by 2 fibromuscular bands that hook around the neck and the pelvic part of the urethra and fix them to the postero-inferior part of the 2 pubic bones. Male - Female

Relations: Males: anterior to rectum, above prostate Females: inferior to uterus, anterior to vagina

Nerve Supply: 1-Sympathetic: Through the vesical plexuses through Hypogastric plexuses and nerves 2- Parasympathetic: Pelvic Hypogastric nerves and Inferior Hypogastric Plexus

Urethra

Urethra Female ~ 4cm long opens to exterior between clitoris and vaginal opening Male ~ 20 cm long passes through prostate gland pierces urogenital diaphragm enters penis and extends throughout length opens at urethral orifice Urethra

It is a common duct for both the urinary and genital systems allowing for the passage of both urine and semen to the outside Male Urethra

Parts: Prostatic urethra (1 ½ inches) = widest part : Passes through the prostate gland 2. Membranous urethra (1/2 inch) = narrowest part: Passes through the urogenital diaphragm 3. Penile or spongy urethra (6 inches) : Passes through the length of the penis

Female Urethra It is short, about 1 ½ inches (4 cm) long. - It extends from the neck of the urinary bladder, then it passes downwards and forwards. - It lies just anterior to the vagina. Female Urethra

Nerve Supply Male: Prostatic Plexus Female: Vesical Plexus and Pudendal nerve Nerve Supply

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