Pelvic Fascia, Rectum & Anal Canal; Urinary Bladder & Female Urethra Flashcards
Identify the structures indicated in pink & green.
How are they formed?
What are their functions?
- Green: Pararectal fossae
- Pink: Paravesical fossae
- The peritoneum reflects laterally over the bladder & the rectum forming the shallow fossae
- Allow for bladder & rectum to distend when needed
What peritoneal pouches exist in the female & male bodies respectively?
How are they formed?
- Peritoneum continues posteriorly & reflects over the rectum making these pouches
- Female
- vesicouterine pouch
- betweent the bladder & uterus
- rectouterine pouch (pouch of Douglas)
- between rectum & uterus
- vesicouterine pouch
- Male
- rectovesical pouch
- between rectum & bladder/prostate
- rectovesical pouch
What structures are depicted by the blue & yello lines?
How are the different?
They are what component of the pelvic fascia?
What structure exists between them?
- Membranous component
-
Visceral layer
- directly ensheaths pelvic organs
-
Parietal layer
- lines inner aspect of the pelvic floor & pelvic walls
- continuous with transverslis fascia of the abdomen
-
Visceral layer
- Between those two membranous layers is the endopelvic fascia
- loose areolar tissue
What is the function of septa and ligaments in the pelvic fascia?
- Septa: are located between viscera (rectovaginal septum, rectovesical septum)
- ligaments help suspend viscera (puboprostatic ligament, pubovesical ligament)
What are the two potential spaces in the endopubic fascial?
What are the septa between viscera?
- Potential space (Female + Male)
- retropubic space
- between pubis & bladder
- retrorectal space
- between rectum & sacrum
- retropubic space
- Septa - between viscera
- Female: rectrovaginal septum
- between rectum & vagina
- prevents rectum from bulging in towards the vagina
- Male: Rectovesical septum
- between rectum & prostate
- helps support those two organs
- Female: rectrovaginal septum
What are the ligaments of the pelvic fasia?
- Female
- pubovesical ligament
- from pubis to bladder
- pubovesical ligament
- Male
- puboprostatic ligament
- from pubis to prostate
- puboprostatic ligament
Describe the relationship between the peritoneum & the rectum
- Superior 1/3
- anterior
- lateral
- Middle 1/3
- anterior
- Inferior 1/3
- none
How long is the rectum?
What are its functions?
- Length: 12-15 cm
- Function
- accumulate & temporarily store feces
- defecation adn fecal continence
- water absorption
What are the difference between the anatomy of the colon & rectum?
- Rectum
- no tenia, haustra or appendices
- tenia coli from sigmoid colon spread out to form longitudinal outer layer or smooth muscle
- this occurs at the rectosigmoid junction ~S3
Describe the course of the rectum
- Two anterior-posterior flexure
- Sacral flexure
- follows curve of sacrum (concave anteriorly)
- Anorectal flexure
- sharp posterioinferior bend
- rectum is ending, anal canal is beginning
- formed by puborectalis muscle
- Sacral flexure
- 3 lateral flexures (formed by transverse folds)
- superior
- middle (intermediate)
- inferior
What are the three internal transverse folds of the rectum?
They create what lateral flexures?
What structure exists right above the pelvic floor?
- Folds
- Semi-circular
- Permanent
- Form sharp lateral flexures
- Lateral flexures
- upper lateral curvature
- middle lateral curvature
- lower lateral curvature
- Above pelvic floor
- rectal ampulla (enlargement of the rectum)
- continuous with anal canal
What visceral structures are in direct contact with the rectum in female & male bodies?
- Female
- vagina
- Male
- Urinary bladder
- terminal ureters
- ductus deferens
- seminal glands
- prostate
- Urinary bladder
Identify the indicated features of the provided image
Describe the importance of each feature
- Anorectal line
- where anal canal begins (in line with puborectalis)
- Pectinate line
- divides anal canal in half
- each half supplied by different neurovascular structures
- anal columns
- separated by anal sinus
- pectinate runs along the bottom of this
- White line of Hilton (intersphincteric groove)
- where internal & external anal sphincters meet up
- anal verge = junction of mucosa & pure anal skin
Identify the indicated features of the provided image
What are the muscle layers of the rectum?
- Outer longitudinal layer
- taenia coli of the sigmoid colon as they spread out at the rectosigmoid junction
- Inner circular layer
How are the structures of internal and external anal sphincer different?
- Internal Anal Sphincter (IAS)
- thickening of inner circular muscle layer
- upper 2/3 of anal canal
- smooth muscle, involuntary
- maintains normal resting tone & will relax under parasympathetic influence when there is solid stool w/in the rectum
- External Ana Sphincter (EAS)
- entire length of anal canal
- skeletal muscle, voluntary
- keeps anal canal closed & relaxes during defacation
- innervated by branches from pudendal nerve
Identify the indicated features of the provided image
What arteries supply the rectum & anal canal?
- Superior rectal artery (from IMA)
- main supply to rectum
- Middle rectal arteries (R/L) (from Internal Iliac)
- supply muscle layers
- Inferior rectal arteries (R/L) (from Internal Pudendal, form Internal Iliac)
- supply anal canal
- All of these branches form an anastamoses along the rectum, making incidence of rectal ischemia relatively low
What veins drain the rectum & anal canal?
What is a unique features of these veins?
- Veins accompany arterial supply
- superior rectal
- drain into inferior mesenteric – to portal system
- middle rectal
- drain into internal iliac – to caval system
- inferior rectal
- drain internal pudendal – to caval system
- superior rectal
- Since veins draining the rectum & anal canal are entering two differen system, Portal and Caval, this creates a site of portosystemic anatomosis
- portal hypertension can result in dilation of these vessels
What are the two diferent types of hemorrhoids & how are the different?
- Internal hemorrhoids
- above pectinate line (prolapse rectal mucosa)
- superior rectal veins
- visceral innervation: not painful
- External hemorrhoids
- below pectinate line
- inferior rectal veis
- somatic innervation: painful
Describe the descent of the ureters & where stones are most likely to get stuck
- descend through abdomen
- cross the common iliac artery
- continue down the lateral walls of the pelvis
- turn anteromedially & enter the base of the bladder
- Females: crossed by uterine artery
- Males: crossed by ductus deferens
- Places stones are likely to get stuck:
- crossing into the pelvis over common iliac
- coming into bladder wallD
Where in the pelvis is the bladder located when it is empty vs. full?
- Empty
- lesser pelvis
- just behind/level with pubic symphysis
- lesser pelvis
- Full
- enters grater pelvis (can rise all up to level of umbillicus)
- peritoneum is pulled away fromt eh anterior abdominal wall as the bladder expands
- helpful when placing a catheter & understanding how to access the bladder without perforating the peritoneum
Identify the external features of the bladder
- superior surface
- 2 inferolateral surfaces
- Base (fundus)
What are the defining landmarks of the Trigone?
Internal featues of the bladder
- openings of ureters
- interureteric ridge
- internal orifice of the urethra
What is the main function of the detrusor?
It is innervated by what nerve?
- Muscular wall of the bladder – multidirectional fibers
- Function:
- contract during urination, which pushed urine out of the bladder into the urethra
- Innervation:
- Pelvic splanchnic nerves (parasympathetic)
- Inferiorly, detrusor muscles form the internal sphincter of urethra (involuntary)
An obstruction to urination can have impact to the detrusor muscle?
can cause hypertrophy
What lymphatic nodes drain the bladder?
- Superior surface of bladder is drained by external iliac nodes
- Base of the bladder is drained by internal iliac nodes
The female urethra is fused to what structure?
Where does originate & terminate?
Why are UTIs more common in females?
- Originates at internal urethral orifice & terminates at external urethral orifice
- Passes in atero/infero direction fused to anterior wall of vagina
- UTIs are more common in females because
- urethra opens into the vestibule of the vagina - direct exposure to pathogens
- the urethra is not very long, so the pathogens do not have to travel very far to get to the bladder
Identify the indicated features of this sagital MRI
