Bony Pelvis and Pelvic Wall Flashcards
How can you tell if the sacrum is in anatomical position?
ASIS and anterior pubis are in the same vertical plane
When do the ilium, ischium, and pubis fuse?
puberty
Who gets pelvic fractures more: children or adults?
adults
pelvic bones fuse at puberty, so the 3 bones are more flexible until they fuse
What are the anatomical landmarks of the ilium?
- iliac crest
- iliac fossa
- anterior superior iliac spine
- anterior inferior iliac spine
- arcuate line
- iliac tuberosity
- posterior superior iliac spine
- anterior gluteal line
- posterior gluteal line
What are the anatomical landmarks of the ischium?
- ischial spine
- ischial body
- ischial tuberosity
- ischial ramus
What are the anatomical landmarks of the pubis?
- superior pubic ramus
- pectineal line
- pubic tubercle
- pubis, body
- symphyseal surface
- inferior pubic ramus
What ligament(s) are between the sacrum and ilium?
anterior sacroiliac L
posterior sacroiliac L
What are the functions of the sacrospinous L and sacrotuberous L?
prevent rotation of sacrum and coccyx
What is the other name for the greater pelvis?
false pelvis
What is the other name for the lesser pelvis?
true pelvis
What type of compression fracture causes multiple breaks?
anterior posterior compression - car accident
What type of fracture causes fracture of acetabulum?
lateral compression
What are the weak points of the pelvis?
- pubic rami
- acetabulum
- sacroiliac joints
- iliac ala
What is the male pelvis called?
android pelvis
What is the female pelvis called?
gynecoid pelvis
Desccribe the android pelvis
- general
- greater pelvis
- lesser pelvis
- pelvic inlet
- pelvic outlet
- pubic arch/angle
- obturator foramen
- acetabulum
- greater sciatic notch
- general: thick and heavy
- greater pelvis: deeper
- lesser pelvis: narrow and deep
- pelvic inlet: heart shaped
- pelvic outlet: smaller
- pubic arch/angle: <70 degrees
- obturator foramen: round
- acetabulum: large
- greater sciatic notch: narrow ~70 degrees
Decribe the gynecoid pelvis
- general
- greater pelvis
- lesser pelvis
- pelvic inlet
- pelvic outlet
- pubic arch/angle
- obturator foramen
- acetabulum
- greater sciatic notch
- general: thin and light
- greater pelvis: shallow
- lesser pelvis: wide and shallow
- pelvic inlet: oval, cylindrical, wide
- pelvic outlet: larger (wider)
- pubic arch/angle: wide > 80 degree
- obturator foramen: oval
- acetabulum: small
- greater sciatic notch: large ~90 degrees
What does the greater pelvis contain?
abdominal viscera
What contains the lesser pelvis?
pelvic bones
What is the other name for the pelvic inlet?
superior aperture
What is the other name for the pelvic outlet?
inferior aperture
What are the main pelvic wall muscles?
- piriformis
- obturator internus
- coccygeus
What muscles work together to laterally rotate the thigh?
obturator internus and piriformis
Where does the obturator internus attach?
greater trochanter
Where does the piriformis attach?
greater trochanter
What is the action of the piriformis?
laterally rotate the thigh
What is the action of the obturator internus?
laterally rotate the thigh
What is the function of the coccygeus m?
supports pelvic viscera and flexes coccyx
The pelvic floor is also the ____
roof of the peritoneum
What are the pelvic floor muscles?
coccygeus
iliococcygeus
pubococcygeus
puborectalis
What are the levator ani function?
elevate the anal canal
What is the tendinous arch of levator ani?
thickening of obturator internus fascia between ischial spine and pubic body
What does the tendinous arch of the levator ani divide?
obturator internus m into superior pelvic region and inferior perineal portion
What is the anorectal angle created by?
puborectalis m
What is the function of the anorectal angle created by the puborectalis m?
helps maintain fecal continence
- will relax during urination and defecation
- works independently from sphincters
What are the levator hiatus?
openings created by pelvic floor muscles - anterior gap in levator ani muscles
- passageway for the urethra, rectum, and vagina
- anteromedial fibers of pubococcygeus and puborectalis
What is the order of the levator ani from medial to lateral?
puborectalis
pubococcygeus
iliococcygeus
What are the most susceptible muscle to tear during childbirth?
puborectalis m
pubococcygeus m
What is the ischiorectal fossa filled with?
fat, neurovasculature
What is the function of the ischio-anal fossae?
allows movement of pelvic diaphragm and expansion of anal canal
What are the triangles of the ischial-anal fossae?
urogenital triangle and anal triangle (front and back)
What are the two flexures?
- sacral flexure/dorsal bend
- anorectal flexure/ventral bend/perineal flexure
What is the dorsal bend due to?
concave form of sacrum
What is the ventral bend due to?
encirclement of the rectum by the levator ani (puborectal sling)
-point where rectum transitions to anal canal
What are the parts of the anal canal?
- anal columns
- anal valves
- anal sinuses
- external anal sphincter
- internal anal sphincter
- pectinate line
What are anal columns?
longitudinal ridges
What are anal valves?
folds at the base of the columns
What are anal sinuses?
adjacent to valves
-secrete mucus to facilitate defication
What are the parts of the external anal sphincter?
- subcutaneous
- superficial
- deep
What percent of anal tone is the external anal sphincter doing?
15-30%
What percent of anal tone is the internal anal sphincter doing?
55-85%
What type of muscle is the external anal sphincter?
skeletal
Is the external anal sphincter voluntary or involuntary?
voluntary
What type of muscle is the internal anal sphincter?
circular smooth m
Is the internal anal sphincter voluntary or involuntary?
involuntary
What is the function of the internal anal sphincter?
tonic contraction except when feces fill rectum
What does the pectinate line divide?
upper 2/3 anal canal from lower 1/3 anal canal
Above pectinate line
-embryological origin
endoderm
below pectinate line
-embryological origin
ectoderm
above pectinate line
- nerves
- veins
- hemorrhoid classification
- destination of lymph
- nerves: inferior hypogastric plexus (visceral - mixed symp and para)
- veins: superior rectal v (portal)
- hemorrhoid classification: internal (not painful)
- destination of lymph: internal iliac lymph nodes, inferior mesenteric
below pectinate line
- nerves
- veins
- hemorrhoid classification
- destination of lymph
- nerves: inferior rectal N (somatic)
- veins: inferior rectal v (systemic)
- hemorrhoid classification: external (painful)
- destination of lymph: superficial inguinal lymph nodes
describe internal hemorrhoid
- above pectinate line
- bright red blood
- not painful
- prolapsed rectal mucosa due to weakened muscularis mucosa and abundant arteriovenous anastamosis
describe external hemorrhoids
- below pectinate line
- painful: hurts when wiping
- external venous plexus covered with epidermis
What are hemorrhoids a consequence of?
portal hypertension
describe the lymph drainage
-superior rectum
superior rectum –> pararectal lymph nodes –> sacral lymph nodes –> inferior mesenteric lymph nodes
describe lymph drainage
-inferior rectum
inferior rectum –> internal iliac lymph nodes
describe lymph drainage
-anal canal (below pectinate line)
anal canal–> superficial lymph nodes
