URETERS URINARY BLADDER URETHRA

OBJECTIVES At the end of the lecture, students should be able to: Describe the course of ureter & identify the sites of ureteric constriction Describe the important relations & identify certain areas (trigone, uvula vesicae) in the base of urinary bladder. List the blood supply, lymphatic drainage & nerve supply of urinary bladder Differentiate between male & female urethra regarding length, structure, course & function.

Ureter A 25 – 30 cm long muscular tube transporting urine from kidney to urinary bladder. Begins as a continuation of renal pelvis. COURSE IN ABDOMEN: It descends anterior to psoas major muscle (opposite the tips of lumbar transverse processes). It crosses the end (bifurcation) of common iliac artery to enter the pelvis.

COURSE IN PELVIS & TERMINATION: Runs downward in front to internal iliac artery, reaches ischial spine Turns forward and medially , enters the upper lateral angle of urinary bladder Near its termination, is crossed by the vas deferens Passes obliquely through the wall of bladder for about ¾ inch before opening into the bladder cavity. Bladder muscle contraction mechanically closes off ureteral orifice which prevents a reverse flow of urine toward the kidney

Ureteric Constrictions The normal ureter is not of uniform caliber and shows constrictions at three points (possible sites of obstruction and stone impaction) At the ureteropelvic junction At the crossing of external/common iliac artery At site of entrance to bladder (uretrovesical junction; narrowest part) 1 2 3

Arterial Supply Ureter is supplied by multiple arteries throughout its course From above downward, these are:: Renal artery Gonadal artery Common iliac artery Internal iliac artery 1 2 3 4

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

An empty bladder is pyramidal in shape having: An apex A base (posterior surface) Three surfaces: A superior surface Two infrolateral surfaces A neck

Apex: Directed forward Lies behind the upper margin of the symphysis pubis Is connected to umbilicus by the median umbilical ligament (contains urachus, the remnant of allantoise)

Base (Posterior surface): Triangular in shape Upper part covered by peritoneum Lower part related to: In males: vas deferentia and seminal vesicles. In females: vagina.

Superior surface: Completely covered by peritoneum. Related to: In males: coils of ileum or sigmoid colon In females: uterus Male pelvis Female pelvis

Infrolateral surfaces: Related: In front to the retropubic pad of fat & the pubic bones Posteriorly lie in contact with obturator internus above and levator ani below Retropubic fat Accomodates distention of bladder Continuous with fat in the anterior abdominal wall. Rupture of bladder results in escape of urine to anterior abdominal wall

Neck: Lies inferiorly, and is the most fixed part of the bladder Is related to lower border of symphysis pubis In male, rests on the upper surface of prostate. Here, the smooth muscle fibers of the bladder are continuous with those of the prostate. The circular muscle fibers thickened to form the sphincter vesicae

Interior of the Urinary Bladder Mucous membrane thrown into folds except in the triangular region in the base of bladder, between the openings of the two ureters and the urethra. This region is called the ‘trigone’. Here The mucous membrane is always smooth even when the bladder is empty Uvula vesicae, a small elevation in the mucous membrane, located just behind the internal urethral orifice. It is produced by the median lobe of prostate.

Blood & Nerve Supply Arterial supply: from internal iliac artery Venous drainage: into internal iliac vein Lymphatics: into internal iliac lymph nodes The nerves form the vesical nerve plexus that contains: Sympathetic fibers derived mainly from L1,2 Parasympathetic fibers derived from pelvic splanchnic nerves S2,3,4 Sensory fibers from the bladder are visceral and transmit pain sensation resulting from overdistention

The normal capacity of bladder is about 300-500ml. As bladder fills, it becomes circular in shape & its superior surface bulges upward into abdominal cavity. 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

Male Urethra About 8 inches (20cm) long Extends from the neck of bladder to the external urinary meatus on the tip of the glans penis Divided into three parts: Prostatic Membranous Penile

Penile (spongy) urethra Prostatic urethra Length= 3 cm Widest & most dilatable Extends from neck of bladder inside prostate gland Structures openings into prostatic urethra: Ejaculatory ducts Ducts of prostate gland Penile (spongy) urethra Length=16 cm Narrowest part of whole urethra Extends throughout penis & opens externally through external urethral orifice Membranous urethra Length=1 cm Surrounded by external urethral sphincter

Female Urethra Length= 4 cm Extends from neck of urinary bladder to open externally through the external urethral orifice (anterior to the vaginal opening) Has only urinary function Trigone

FLY HIGH Thanks & Good Luck