The Ureter, Prostate and Bladder Flashcards
Ureters in situ
-The ureters are part of the urinary system and they carry urine from the kidneys to the urinary bladder
-They run inferiorly from the renal pelvis, crossing over the bifurcation of the common iliac arteries at the level of the pelvic inlet (pelvic brim)
-Then run along the lateral wall of the pelvic cavity and enter the urinary bladder
What are the 3 parts of the ureter anatomically?
-Abdominal (from kidney to pelvic inlet)
-Pelvic (from pelvic inlet to bladder wall)
-Intramural (passes through the bladder wall)
Ureters in pelvic cavity
-After crossing the pelvic brim over the bifurcation of the common iliac artery, the ureters run along with the internal iliac arteries within the pelvic cavity
-Shortly before curving anteromedially to enter the urinary bladder in an inferomedial direction
-In males, the ureters pass posterior to the ductus deferens
-In females, the uterine artery crosses superoanteriorly to the ureter (“water under the bridge”)
Blood supply
-Due to its long course, the blood supply to the ureter varies depending on its level
-In the abdominal region, its branches derived mainly from the renal and gonadal arteries
-As it crosses the pelvic brim, its branches arise from the common iliac arteries
-Within the pelvic cavity, it receives blood supply from branches of the superior and inferior vesical arteries (also supply the bladder) and uterine artery (also supplies the uterus in females)
Urinary venous system on X ray
Ureteric constrictions
Ureters demonstrate relative constrictions in three places (potential sites of ureteric stones):
-At the junction of the ureters and renal pelvis (ureteropelvic junction)
-Where the ureters cross the brim of the pelvic inlet over the bifurcation of the common iliac artery
-During their passage through the wall of the urinary bladder (urterovesical junction)
-Occasionally a fourth constriction is identified where the gonadal vessels pass anterior to the ureter
Bladder position
-When empty, the adult urinary bladder is located in the lesser pelvis, lying close to the pubic bones
-When full, it can reach as high as the umbilicus
-Extraperitoneal structure meaning that it lies mostly inferior to the peritoneum
-In females, the uterus lies superoposterior to the bladder and in males the rectum lies posterior to it
Bladder structure
-The apex of the bladder points toward the superior edge of the pubic symphysis when the bladder is empty
-The fundus is opposite the apex with the body sandwiched in between
-The walls of the bladder are composed chiefly of the detrusor muscle (multiple layers that run in different direction)
-The muscle fibres form the involuntary internal urethral sphincter toward the neck of the bladder (in males) This sphincter controls the outflow of urine and prevents retrograde ejaculation.
-The area marked by the ureteric orifices and the internal urethral orifice is the trigone. The bladder is lined by transitional epithelium except at the trigone
Bladder nervous innervation
-The preganglionic sympathetic fibres are carried by the lumbar splanchnic nerves (L1-3) to the inferior mesenteric ganglion and synapse
-The postganglionic sympathetic fibres travel in the superior hypogastric plexus, down to the inferior hypogastric plexus
-They are joined by parasympathetic fibres coming from the pelvic splanchnic nerves (S2-4)
Micturition
-As urine accumulates, the bladder wall is stretched, and this stimulates visceral afferent fibres and causes almost a reflex-like action
-It is the parasympathetic innervation that causes contraction of the detrusor muscle and inhibition to the internal urethral sphincter
-Consequently, the bladder wall contracts, the internal urethral sphincter relaxes and urine flows into the urethra
-There is no internal urethral sphincters in females and urinary continence is maintained by the contraction of the levator ani and external urethral sphincter
-The external urethral sphincter is innervated by somatic nerve fibres but the internal urethral sphincter is innervated by autonomic nerve fibres
Accessory reproductive glands
-The prostate gland is an organ of the male reproductive system
-Located at the bladder outlet and encircles the urethra. It sits anterior to the anterior wall of the rectum.
-Prostatic secretion make up 30% of the volume of the ejaculate and is important for spermatozoa motility
-Secretion from the seminal vesicles makes up 70% of the volume of the ejaculate and is an important source of energy for the spermatozoa
-Bulbourethral glands secrete a clear watery fluid that prepares the urethra for the passage of the sperm
What are the accessory reproductive glands?
-Prostate gland
-Seminal vesicles
-Bulbourethral glands
Prostate relations
-The ejaculatory ducts are formed by the union of the ducts of the seminal vesicles with the ductus deferens
-They arise from near the neck of the bladder and run close together as they pass anteroinferiorly through the posterior part of the prostate
-They converge and open into the prostatic urethra
Ejaculation
-All the structures involved in ejaculating are richly innervated by sympathetic nerve fibres
-The preganglionic sympathetic fibres are carried by the lumbar splanchnic nerves (L1-3) to the hypogastric plexuses
-Sympathetic innervation stimulates contraction of the internal urethral sphincter to prevent retrograde ejaculation. -It also stimulates rapid contractions of the ductus deferens and secretions from the accessory glands
Hypertrophy of prostate
-Enlargement or benign hypertrophy of the prostate (BHP) is common after middle age
-An enlarged prostate projects into the urinary bladder and impedes urination by distorting the prostatic urethra.
-Leads to voiding dysfunction such as: =>shortened micturition interval
=>weak urinary stream
=>strained efforts/pain when urinating
-Sustained obstruction of the bladder outlet leads to:
=>bladder wall hypertrophy
=>residual urine retention
=>backlog of urine up the ureters and kidneys (increased risks of infections)
