ANATOMY OF PELVIS ANORECTUM AND PERITONEUM Flashcards
What are the two parts of the pelvis
false/greater and true/lesser pelvis
what makes up the false pelvis
from the iliac crest to pubic symphysis
what makes up the true pelvis
pubic symphysis to the sacrum
what is the pelvic floor and pelvic outlet made of
pelvic floor is muscles and ligaments and the pelvic outlet is formed by the perineum
where do the perineal membrane lie
inferiorly to the anterior part of the pelvic floor
what three ligaments attach to the pelvic wall
sacrospinous ligament
sacrotuberous ligament
obturator membrane (the circular part)
what is the function of the ligaments
stabilize the sacrum to the pelvis and keeps it in line
what are apertures
tiny holes or openings
what does the sacrospinous ligament divide
the sciatic foramen into a greater one superiorly and a lesser one inferiorly
what aperture does the obturator membrane cause
obturator canal
what two muscles are part of the lateral pelvic wall
piriformis and obturator internus
where does the piriformis attach
from the sacrum through the greater sciatic foramen to the greater trochanter of the femur
what nerves innervate the piriformis
brnaches from S1 and S2
what is the function of the piriformis
laterally rotates the hip joint and abducts the hip
where does the obturator muscle attach
to the obturator and surrounding bone ( looks like a fan)
which nerves innervate the obturator internus
from L5 and S1
what is the function of the obturator internus
laterally rotates the hip joint anf abducts the hip
what muscle is part of the inferolateral part of the pelvic wall
ischiococcygeus/coccygeus
where does the ischiococcygeus attach
from ischial spine to the coccyx
which nerve innervates the ischiococcygeus
S3 and S4
what is the function of ischiococcygeus
pulls the coccyx forward after defecation
what muscles make up the pelvic floor
levator ani muscles
what are the levator ani muscles
muscle pairs which originate from each pelvic wall and meet in the middle
what are the two openings in the levator ani muscles
urogenital hiatus - passage for urethra and vagina
rectal hiatus - passage for anal canal
what structure do the levator ani muscles cover
the lesser sciatic foramen
what three muscles make up the levator ani
pubococcygeus
puborectalis
iliococcygeus
what nerves innervate the levator ani
anterior rami of S4
pudendal nerve S2-S4
what is the main muscle involved in defecation
puborectalis
what happens to the anorectal angle and puborectalis during continence (resting)
the anorectal angle is maintained
contraction of puborectalis
what happens to the anorectal angle and puborectalis during defecation
the anorectal angle straightens
relaxation of puborectalis
what two structures of the perineal pouch are common in both males and females
external urethral sphincter and deep transverse perineal muscles
what two muscles do women have in the perineal pouch and what do they do
sphincter urethrovaginalis
compressor urethrae
facilitate the closing of the urethra
where is the sphincter urethrovaginalis
surrounds the urethra and vaginal hiatus
where is the compressor urethrae
from ischiopubic rami to the urethra
what nerve innervates the perineal pouch
pudenal nerve S2 to S4
what muscle forms the perineal body
deep transverse perineal muscles
what are two shared structure/fold in the peritoneum common to both males and females
median umbilical fold
medial umbilical fold
what part the rectum is not covered/partially covered by the peritoneum
middle third partly
lower third not
where are the median and medial umbilical folds
the medial one is more superior than the median
what are two pouches found in the peritoneum of women
vesico-uterine
recto-uterine (pouch of douglas)
what pouch is found in the peritoneum of males
rectovesical
what are fascia lines
they cover the pelvic walls and cavity forming sheaths around vessels and nerves
what are the two types of fascia in males
prostatic fascia
retrovesical septum
where does the rectum extend from
from the sigmoid colon at S3. ends as it passes through elevator ani. Stops 15cm from the anal orifice
what are the three lateral curves in the rectum
curves right at the upper part
curves really left in middle
curves right at the end
what are the 2 semi lunar transverse folds
mucosa which is circular and longitudinal muscle - can see it externally
devoid of longitudinal muscle
which direction does the rectum move in relation to the sacrum
posteriorly in concavity with the sacrum then curves anteriorly
what is the anorectal flexure
when the rectum curves from anterior to posterior
where is the anorectal flexure in males and females
in males its at the level of the prostate and in females its slightly below the coccyx
what landmark can it be used to palpate in females
he posterior all of the vagina and cervix
where does the anal canal begin
at the end of the rectal ampulla
what is the pectineal line
divides the anus into upper and lower regions
what type of muscle lines the upper part of the anus
mucosa and is formed by anal columns and they combine at the pectineal line to form anal values
what type of muscle lines the lower part of the anus
nonkeritanised stratified squamous epithelium
what is the anocutaneous line
ends the anal pecten and becomes true skin leading to the anal orifice
what is the anal sphincter complex
made up of the internal and external anal sphincters
what is the structure of the internal sphincter
its a tight spiral either side of the rectum
where does the external sphincter attach
posteriorly to the anococcygeal and posteriorly to the perineal body
where is the perineum located
inferior to the pelvic floor and between the thighs
what are the two triangle kind of parts of the perineum
the urogenital triangle which is anterior and inferior
the anal triangle which is inferior and posterior at 120 degrees to the urogenital triangle
what nerve innervates the anal triangle
rectal branch of the pudenal and anterior rami S4
describe the structure of the ischioanal fossa
funnel shape on the pelvic floor
what muscles/ligaments form the ischioanal fossa
ischium wall, obturator internus and sacrotuberous ligament
what structures are attached to the superficial perineal pouch
roots and joining of the erectile structures that form the external genitalia
