Anatomy of Renal System (II) PDF

ANATOMY OF RENAL SYSTEM (II) Ureter o External Anatomy: w Muscular tube (25–30 cm in length, 3-4 mm in diameter). w Extend from kidneys (in posterior abdominal wall) to posterior surface of urinary bladder (in pelvis). w Transport urine produced in the kidneys to be stored in the blad...

ANATOMY OF RENAL SYSTEM (II) Ureter o External Anatomy: w Muscular tube (25–30 cm in length, 3-4 mm in diameter). w Extend from kidneys (in posterior abdominal wall) to posterior surface of urinary bladder (in pelvis). w Transport urine produced in the kidneys to be stored in the bladder. o Mechanism of Action: 1. Peristaltic contractions (1-5/min). 2. Hydrostatic pressure & gravity. o Route of ureter in abdomen: Þ Starts at hilum as a continuation of renal pelvis (funnel-shaped cavity within renal sinus). Þ Descends in posterior abdominal wall retroperitoneally on Psoas muscle. Þ Crosses over the bifurcation of common iliac artery at pelvic brim to enter the pelvis. Þ As they cross over the pelvic brim, they produce a kink. o Route of ureter in pelvis: Þ Runs downward & backward on lateral wall to the region of ischial spine anterior to internal iliac A. Þ Turns forward to enter posterolateral angle of the bladder (in oblique direction). o Gender differences: w In Males: crossed by vas deferens superomedially near its termination. w In female: Þ Passes behind the ovary. Þ Crosses medial to the origin of uterine artery & then below the broad ligament of the uterus (immediately inferior to uterine artery). Þ Risk of injury during ligation of uterine A. in Hysterectomy procedure “water under the bridge”. o Relations to ureters: w Right ureter: ü Anteriorly: § 2nd part of duodenum. § Right gonadal vessels. § Right colic & ileocolic vessels. 1  ü Posteriorly: § Right Psoas muscle → separates ureter from the tip of transverse prosses of lumber vertebrae. § Bifurcation of right common iliac artery. w Left ureter: ü Anteriorly: § Left gonadal vessels. § Left colic vessels. § Sigmoid colon. ü Posteriorly: § Left Psoas muscle. § Bifurcation of left common iliac artery. ü Medially: inferior mesenteric vein. o Constrictions of ureter: w Potential sites of obstruction by ureteric stones. w Ureter has 3 constrictions along its course: 1. At uretero-pelvic junction: where renal pelvis joins ureter in abdomen. 2. At pelvic brim: where ureter is kinked as it enters the pelvis over the pelvic brim. 3. At uretero-vesical junction: Þ Where it pierces the bladder wall in oblique direction “physiological sphincter” (to prevent back flow of urine when the bladder is filled). Þ Note: peristaltic contraction of the ureter ensures unidirectional flow of urine. Urinary Bladder o Location: w Hollow muscular organ. w Situated in the pelvic cavity posterior to the pubic symphysis. w In Adults: ü Completely in the pelvic cavity (true pelvis) when empty. ü However, as it fills it reaches to abdominal cavity. w Lower level in female due to absence of prostate gland (rests directly on the pelvic diaphragm “levator ani muscle”). o Shape: w Pyramidal (has apex, base, & 3 surfaces) “pear-shaped” when empty. 2 A. Apex: ü Pointed anteriorly. ü Behind the upper margin of pubic symphysis. ü Connected to umbilicus by median umbilical ligament. Þ Umbilical ligament → remnant of urachus. Þ Urachus → remnant of allantois. Þ Allantois → duct that carries urine from fetus's body to the umbilical cord. B. Base (Fundus): ü Faces posteriorly. ü Triangular in shape. ü Superolateral angles are joined by ureters. ü Inferior angle (neck) gives rise to the urethra. ü Superior part of base is covered by peritoneum. ü Important structures are resting on the bladder base: § In male: - Two vasa deferentia passing medially to the two seminal vesicles → separate bladder from rectum posteriorly. - Retrovesical fascia & fat. - Note: rectovesical (retrovesical) pouch: û Peritoneal fold between bladder & rectum. û The lowest point in the abdomen. § In female: - Vagina: posterior to the bladder and separate it from the rectum. - Note: the fold of peritoneum here between the uterus & rectum called rectouterine pouch. C. Superior surface: ü Separates it from: § In males: coils of ileum & sigmoid colon. § In females: - Body of uterus. - Note: uterovesical pouch: fold of peritoneum between the uterus superiorly and the superior surface of the bladder inferiorly. ü As the bladder fills → bulges upward into abdomen → ovoid shape bladder. D. Two inferolateral surfaces. 3 o Internal structure: w Folded into rugae when empty: ü Disappear when fill. ü Exception: over internal surface of the base (Trigone). ü Trigone: § Smooth mucus membrane because it’s strictly adherent to underlying muscular layer. § Superior angles: openings of the two ureters connected by interureteric ridge. § Inferior angle: urethral orifice → protected by internal urethral sphincter (sphincter Vesicae). o Innervation: wSympathetic: ü L1 & L2 ganglia of S.T. ü Descends via hypogastric plexuses (post ganglionic). ü Function: ↓ detrusor & ↑ sphincter → inhibit micturition. w Parasympathetic: ü Pelvic splanchnic nerves (S2, S3, S4). ü Pass through inferior hypogastric plexus (preganglionic) → bladder. ü Function: ↑ detrusor & ↓ sphincter → stimulate micturition. w Afferent (Visceral Sensory): follow parasympathetic pathway → pelvic splanchnic nerves. o Blood supply: by superior & inferior vesicle arteries. Urethra o Small tube that responsible for urine excretion from the bladder. o In Females: w Shorter (4 cm). w Posterior to the pubic symphysis. o In Males: w Longer (20 cm). w Divided into 3 parts: ü Prostatic part: passing through prostate gland. ü Membranous part: passing through urogenital diaphragm. ü Spongy part: passing through the penis. Best wishes 4