GA-Bony Pelvis and the Pelvic wall

Question 1

What level is the pelvic inlet?

Answer 1

level of sacral promontory

Question 2

what bone bears abdominal weight?

Answer 2

pubic bone

Question 3

What is the correct anatomical position of the pelvis?

Answer 3

ASIS and anterior pubis are in the same vertical plane

Question 4

What is the function of the sacroiliac ligaments? which one is thicker?

Answer 4

hold sacrum in place like a wedge between the two hip bones, posterior is thicker

Question 5

what ligaments prevent the pelvis/coccyx/sacrum from rotating too far anteriorly?

Answer 5

sacrotuberous and sacrospinous ligament

Question 6

What are the boundaries of the lesser pelvis? (true pelvis) what spinal level does it start?

Answer 6

superior-pelvic inlet
inferior-pelvic diaphragm
lateral-hip bones (all three)
posterior-sacrum/coccyx

L5-S1

Question 7

what are the boundaries of the greater pelvis? what does it contain?

Answer 7

superior to pelvic brim within the pelvic bones

holds abdominal viscera

Question 8

what passes through the levator hiatus? what are its boundaries?

Answer 8

ureter, rectum, vagina (in females)

boundaries-pubococcygeal, and puborectalis form anterior/medial fibers

Question 9

what are the boundaries of the ischiorectal fossa? what are its contents? what is its function?

Answer 9

inferior-perineal membrane-strong membrane between pubic rami
superior-pelvic floor muscle

contents-fat filled diamond shaped, anorectal and urogenital parts

function: allows movement of pelvic diaphragm and expansion of anal canal for pooing

Question 10

what muscles make up the pelvic wall?

Answer 10

obturator internus
piriformis
coccygeus

Question 11

what is the innervation and function of the obturator internus?

Answer 11

obturator nerve

lateral rotation of thigh, support pelvic wall

Question 12

what is the innervation and function of the piriformis?

Answer 12

innvervation: nerve to piriformis

function-lateral rotation of thigh, support wall

Question 13

what is the innervation and function of the coccygeus m?

Answer 13

innervation: anterior rami of S4-S5
function: support pelvic viscera, flex coccyx

Question 14

what muscles make up the pelvic floor? what is the function of the pelvic floor?

Answer 14

levator ani and ischiococcygeus, to support viscera and control tone of anus

Question 15

what muscles make up the levator ani muscle?

Answer 15

pubococcygeus
puborectalis
iliococcygeus

Question 16

what is significant about the puborectalis muscle?

Answer 16

helps form the anorectal angle and maintains fecal continence
-relaxes during defication and relaxes when you squat so you can poo easier

Question 17

what makes up the tendinous arch of the levator ani?

Answer 17

thickening of obturator fascia between ischial spine and body of pubis

Question 18

what spinal level is the rectosigmoid junction?

Answer 18

S3

Question 19

which anal sphincter contributes the greatest to resting anal tone? is it voluntary or involuntary?

Answer 19

internal, involuntary smooth muscle

Question 20

what nerve innervates above/below the pectinate line?

Answer 20

above: inferior hypogastric n (visceral)
below: inferior rectal nerves (somatic)

Question 21

what veins drain above/below the pectinate line? what type of circulation are they

Answer 21

above: superior rectal vein (portal circulation)
below: inferior rectal veins (systemic)

Question 22

what type of hemorrhoid is painful? why?

Answer 22

external hemorrhoids, they receive somatic innervation so they are painful, internal receive visceral

Question 23

what is the difference between internal and external hemorrhoids?

Answer 23

external are painful and covered in epidermis from the ectoderm

internal are not painful and covered in muscularis mucosa and are from endoderm

Question 24

oh no! you get in a car crash and it crushed your pelvis with an anteroposterior compression force! what is broken? what is a consequence of this break?

Answer 24

fracture of all 4 pubic rami

pelvic instability and genitourinary injury

Question 25

what breaks with lateral compression of the pelvis?

Answer 25

ilia and acetabulums

Question 26

if you jump off a building and land on your feet with your legs straight whats gonna break?

Answer 26

head of femur will dislocate through the acetabulum into the pelvic viscera

Question 27

What are the weak areas of the pelvis?

Answer 27

pubic rami, acetabilum, sacroiliac joints

Question 28

what is the difference between a male and female pelvis?

Answer 28

male has:
smaller pelvic outlet
narrower pubic arch (<70 degrees, female >80)
round obturator foramen (females is oval)
greater sciatic notch is the angle of a V female is 90 degrees

Question 29

what muscles are most susceptible to tearing during childbirth? why?

Answer 29

puborectalis and pubococcygeus

they are the most medial and large part of the levator ani