URINARY SYSTEM 2 Urinary Bladder and Urethra Dr Rania Gabr

Urinary Bladder

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

Shape It has the shape of three-sided pyramid placed on one of its angle (NECK). Apex: Is directed forward Is related to upper border of symphysis pubis Is connected to umbilicus by the median umbilical ligament (remnant of urachus)

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).

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

(BASE) Is directed backward IN MALE: Is related to vas deferens & seminal vesicle of both sides IN FEMALE: Is related to vagina Male Female

(SUPERIOR SURFACE) IN MALE: Is related to coils of ileum & sigmoid colon IN FEMALE: Is related to the uterus Male Female

(INFERO-LATERAL SURFACES) Are related to retropubic fat separating them from pubic bones Retropubic fat Accomodates distention of bladder Continuous with anterior abdominal wall. Rupture of bladder escape of urine to anterior abdominal wall Male Female

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. IN MALE: Is related to upper surface of prostate gland

Mucous membrane is folded. Trigone: a triangular area in base of bladder bounded by the 2 ureteric orifices & internal urethral orifice. Its mucous membrane is elastic (not folded) Mucous membrane is folded.

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

ARTERIES: from internal iliac artery VEINS: into internal iliac vein LYMPH: into internal iliac lymph nodes NERVES: Parasympathetic: pelvic splanchnic nerves from S2, 3, 4 Sympathetic: from L1,2 Sensory: transmitting pain due to overdistention of bladder

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

Male 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

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

Structures openings into prostatic urethra: Ejaculatory ducts: containing sperms & secretion of seminal vesicles Ducts of prostate gland

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.

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

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