Lecture 17: Pelvic Viscera 1 Flashcards
What is a sphincter?
Localised muscle thickening around wall of tubular viscus to control passage of contents and prevent reflux
What is an anatomical/functional sphincter?
Anatomical - clearly defined muscle ring
Functional - walls of tube act as a sphincter when exposed to increased pressure
How long is the ureter and how long is the pelvic ureter?
25cm
12.5cm
What is the intramural part of the ureter?
Part of the ureter that enters the bladder - acts as a functional sphincter
How is urine passed from the ureter to the bladder?
Peristalsis, ureters made up of circular and smooth muscle
Where do the ureters enter the bladder
Posterolaterally through urethral orifices at top of trigone
What happens as the bladder fills?
Pressure increases, causes walls of ureters to close on themselves to prevent reflux of urine
What is the blood supply to the ureters?
Take blood supply from region they are at. Blood vessels in the abdomen pass medially and in pelvis pass laterally
What crosses the ureter in males and females?
Vas deferens and uterine artery
What happens if the ureters get distended?
Because the ureter is smooth muscle it will spasm and fire sensory nerve impulses to CNS - interpreted as being from skin - pain referred to rib, groin or external genitals (T11-L1)
What % of ureters are bifid and what does this cause?
1% - more frequent UTIs
How common are pelvic horseshoe kidneys and why do they occur?
0.2%
As body elongates kidney moves - they may stay joined and cannot meet their destination due to major midline vessels - kidney left in pelvic cavity
Where does the bladder sit?
In the pelvis on the vagina (support)
What covers the superior surface of the bladder and what does this form?
Peritoneal coat - forms rectovescial and uterovesical pouches
What part of the bladder is continuos with the urethra?
Neck
What is the middle fold of peritoneum remnant of and what is it now?
Urachus - median umbilical ligament
What happens if the median umbilical ligament remains patent in adulthood?
Urine from bellybutton
How does the bladder position change?
In abdomen in children - pelvis isn’t large enough until 5/6 to accommodate bladder
What is the inside of the bladder like?
Detrusorr muscle - lots of rug to expand - trigone on posterior wall that retains its shape and position always
What is the base of the trigone?
Intrauteric bar
What sphincter is present in only males (function?) and when may this be damaged?
Internal urethral sphincter - stops reflux of semen during ejaculation - damaged in TERP when cleaning out the prostate
What are the steps of the micturition reflex?
- Reflex arc involving parasympathetic fibres via S2-4 to cause contraction of detrusor muscle
- Relaxation of (involuntary) internal urethral sphincter – sympathetics to T12-L1
- Relaxation of (voluntary) external urethral sphincter and levator ani (S2-4) via pudendal nerve
- Raised intra-abdominal pressure
- Urination
What is a suprapubic puncture?
Penetrating pelvic wall using a catheter - bladder volume must be high so bladder is above pelvic brim
How is the urethra different in males and females?
F - short, straight, easy to catheterise, exits just below clitoris
M - 20cm, bends, difficult to catheterise
What are the 3 parts of the male urethra?
Postatic, membranous, spongy/penile
What gender is urinary incontinence more common in and why?
Females - absence of internal urethral sphincter
What part of the GI tract is in the pelvis?
Descending colon, sigmoid colon and rectum
What spinal segments does the rectum exist at?
S3 to tip of coccyx
What are the features of the rectum?
Muscle coat, no mesentery, distal 1/3 dilated as ampulla, transverse rectal folds for storage of faeces, peritoneum on aspects of upper 2/3, surrounded by rectal fascia that may prevent transmission of cancer cells
