PELVIC VISCERA Urinary bladder urethra Sigmoid colon rectum

PELVIC VISCERA Ø Urinary bladder, urethra Ø Sigmoid colon, rectum Ø Male genital organs: vas deferens, seminal vesicles, prostate Ø Female genital organs: ovaries, Fallopian tubes, uterus, vagina

Ureters, Urinary Bladder & Male Urethra

Ureter Crosses pelvic inlet in front of bifurcation of common iliac artery Ø Runs downward in front to internal iliac artery, reaches ischial spine Ø Turns forward and medially , enters the upper lateral angle of urinary bladder Ø Near its termination, is crossed by the vas deferens Ø

Ureter cont’d Passes obliquely through the wall of bladder for about ¾ inch before opening into the bladder cavity. Ø Bladder muscle contraction mechanically closes off ureteral orifice which prevents a reverse flow of urine toward the kidney Ø

Ureter cont’d The ureter has constrictions at three points: l ureteropelvic junction l crossing of external/common iliac artery l where ureters enter bladder Ø These are also sites of obstruction and stone impaction Ø

Urinary Bladder Located immediately behind the pubic symphysis Ø Shape and relations vary according to the amount of urine it contains Ø An empty bladder is entirely a pelvic organ; as it fills, rises up into the hypogastric region Ø In young child the empty bladder projects above the pelvic inlet Ø

Urinary Bladder cont’d The empty bladder is pyramidal in shape having: Ø An apex Ø A base (posterior surface) Ø A superior surface Ø Two infrolateral surfaces Ø A neck Ø

Urinary Bladder cont’d Apex: Lies behind the upper margin of the symphysis pubis Ø Urachus passes upwards to the umbilicus forming the median umbilical ligament Ø

Urinary Bladder cont’d Base or Posterior surface: Triangular in shape Ø Suprolateral angles joined by ureters Ø Inferior angle gives urethra Ø Upper part covered by peritoneum Ø Lower part related to vas deferentia and seminal vesicles, that separate it from rectum Ø

Urinary Bladder cont’d Superior surface: Ø Completely covered by peritoneum. Along its lateral margin, the peritoneum is reflected to the lateral pelvic wall Ø Is related to the coils of ileum or sigmoid colon

Ø As bladder fills, the superior surface bulges upward into abdominal cavity. Ø The peritoneal lining is peeled off the lower part of anterior abdominal wall and the bladder comes into direct contact with the anterior abdominal wall

Urinary Bladder cont’d Infrolateral surfaces: Related in front to the retropubic pad of fat & the pubic bones Ø Posteriorly lie in contact with the obturator internus above and levator ani below Ø

Urinary Bladder cont’d Neck: Lies inferiorly and rests on the upper surface of prostate. Ø Here, the smooth muscle fibers of the bladder are continuous with those of the prostate Ø The circular muscle fibers thickened to form the sphincter vesicae Ø Held in place by puboprostatic ligament (in male) and pubovesical ligament (in female), formed by thickening of the pelvic fascia Ø

Trigone of the Urinary Bladder The trigone is a smooth triangular region on the internal surface of the base of bladder, between the openings of the two ureters and the urethra Ø Superior angles correspond to openings of ureters and inferior angle to the opening of urethra Ø Limited above by a muscular ridge between the ureteric openings, called the interureteric ridge Ø

Trigone of the Urinary Bladder cont’d The mucous membrane is always smooth even when the bladder is empty (unlike rest of mucous membrane which is thrown into folds in empty bladder) as it is firmly adherent to the underlying muscular coat (detrusor muscle) Ø Uvula vesicae, a small elevation located just behind the urethral orifice, produced by the median lobe of prostate. Ø

Urinary Bladder Ø Arterial supply: Superior & inferior vesical arteries, branches of internal iliac artery Ø Veins form vesical venous plexus, which communicates with prostatic plexus and is drained into the internal iliac vein Ø Lymphatics drain into internal & external iliac lymph nodes

Urinary Bladder: Nerve Supply The nerves form the vesical nerve plexus that contains: l Sympathetic fibers derived mainly from L 1, 2 nerves l Parasympathetic fibers derived from pelvic splanchnic nerves S 2, 3, 4 l Sensory fibers from the bladder are visceral and transmit pain sensation resulting from overdistention Ø Micturition reflex Ø

Male Urethra About 8 inches long Ø Extending from the neck of bladder to the external urinary meatus on the tip of the glans penis Ø Divided into three parts: Ø l l l Prostatic Membranous Penile

Prostatic Urethra Widest and the most dilatable part of the urethra Ø About 11/4 inches long Ø Begins at the neck of the bladder, becomes continuous with the membranous urethra at the apex of the prostate Ø Posterior wall shows urethral crest, prostatic sinus, prostatic utericle, openings of the ejaculatory ducts Ø

Uvula vesicae Prostatic utericle & openings of the ejaculatory ducts

Membranous Urethra About ½ inch long Ø Least dilatable part Ø Lies within the urogenital diaphragm surrounded by the sphincter urethrae muscle Ø

Penile (Spongy) Urethra Ø Ø Ø About 6 inches long Enclosed in the bulb and corpus spongiosum of the penis Within the glans penis, it is dilated to form the fossa terminalis (navicular fossa) Receives the openings of the ducts of the bulbourethral glands just below the urogenital diaphragm External urinary meatus is the narrowest part of the entire urethra navicular fossa External urinary meatus

Clinical Notes Urinary retention Ø Suprapubic aspiration Ø Ureteric stones: impaction at the constrictions Ø

FLY HIGH