2. Anatomy of the Pelvis Flashcards
Label A-E of the pelvis.
A: greater (false) pelvis
B: lesser (true) pelvis
C: pelvic brim/inlet (divides the greater and lesser pelvis)
D: pelvic outlet
E: perineum
Label A-G of the pelvis.
A: iliac crest
B: PSIS
C: ASIS
D: ischial spine
E: ischial tuberosity
F: pubic tubercle
G: superior pubic ramus
Label A and B and state what they form.
A: arcuate line
B: pectineal line
Form the pelvic brim
List the ligaments of the pelvis.
What 2 structures does the inguinal ligament go between?
How is the sacrum rotated?
What do the pelvic ligaments do?
What nerve goes through the greater sciatic foramen?
Sacrotuberous, sacrospinous, sacroiliac. Symphysis pubis is a secondary cartilaginous joint that unites articular surfaces.
Pubic tubercle and ASIS
Body weight transmitted through the spine rotates the sacrum forwards
Sacrospinous and sacrotuberous ligaments prevent the lower end of the sacrum being rotated upward at the sacroiliac joint. They stabilise the pelvis. They also convert the sciatic notch into the greater and lesser sciatic foramina.
Sciatic
Label A-E
A: sacrospinous ligament
B: sacrotuberous ligament
C: obturator canal
D: obturator membrane
E: greater and lesser sciatic foramen
Label A-C
A: sacroiliac
B: sacrospinous
C: sacrotuberous
Label A-E
A: anterior sacroiliac ligament
B: sacrospinous
C: sacrotuberous
D: pectineal line
E: pubic symphysis
How does the female pelvis differ from the male?
Adapted for childbirth. Shallower, wider, smoother. Pelvic cavity larger and cylindrical. Pubic arch wider (b/c ischial tuberositites further apart). Pelvic outlet larger. Pelvic inlet similar. Pregnancy hormones allow stretching of ligaments and increase movement - 10% increase in transverse diameter. Not as ideal for locomotion, wider acetabular so femur less directly over knees.
Label A and B.
What runs from the sacral promontry to the symphysis pubis?
A: pelvic inlet
B: pelvic outlet
Diagonal conjugate.
What structures make up the three pelvic walls:
a) anterior wall
b) posterior wall
c) lateral walls
a) pubic rami and symphysis
b) sacrum, coccyx and piriformis
c) hip bone below pelvic inlet, obturator membrane, sacrospinous and sacrotuberous ligaments, obturator internus muscle
Label A-C
A: sacroiliac
B: sacrospinous
C: sacrotuberous
Label A-C
A: piriformis (leaves pelvis through greater sciatic foramen)
B: coccygeus (overlying sacrospinous ligament)
C: obturator internus (leaves pelvis through lesser sciatic foramen)
What is above and below the pelvic floor?
What forms the pelvic floor (diaphragm)?
Is the pelvic floor complete?
Above: main pelvic cavity. Below: perineum
Levator ani muscles, coccygeus muscles and their covering fascia.
No - incomplete anteriorly (urethra and vagina in females)
Label A-C.
What does the green line indicate?
A: levator ani
B: coccygeus
C: piriformis
Levator ani muscle attachment
Label A and B
A: obturator nerve
B: pudendal nerve (goes to perineum behind the pelvic floor)
The levator ani (pelvic floor) is divided into what 4 parts? Describe them.
1) levator prostate/ sphincter vaginae: forms sling around prostate/vagina and inserts into the perineal body (support prostate/constrict vagina)
2) puborectalis: sling from pubic bone around rectoanal junction
3) pubococcygeus: pubis to anococcygeal body (fibrous mass between tip of coccyx and anal canal)
4) iliococcygeus: ilium to anococcygeal body and coccyx
JOIN TOGETEHR IN MIDDLE AT MIDLINE (LEVATOR) RAPHE
Label A-H of this male pelvic floor.
A: levator prostatae
B: puborectalis
C: pubococcygeus
D: iliococcygeus
E: levator ani
F: coccygeus
G: midline raphe
H: piriformis
Label A-D of this female pelvic floor.
A: puborectalis and pubococcygeus
B: iliococcygeus
C: coccygeus
D: piriformis
Label A-C
A: iliococcygeus
B: pubococcygeus
C: puborectalis
What does the levator ani do?
How might the pelvic floor get injured, and what might pelvic floor injury cause?
Supports and maintains pelvic viscera in position. Resists intrapelvic pressure and expulsive efforts of abdominal muscles. Assists sphincter urethrae (EUS). Important sphincter action on the ano-rectal junction (also sphincter of the vagina). Helps support vertebral column.
Difficult childbirth - levator ani muscles fail to recoil and take up previous position. Causes: uterine and vaginal prolapse, herniation of bladder (cytocele), alteration of position of bladder neck - stress incontinence, prolapse of rectum.
What does puborectalis do?
Compare fractures of the false and true pelvis.
What are some complications of pelvic fractures?
Maintains anal angle at the anorectal junction which is important for anal continence. Retracts the mucous membrane of the lower anal canal. [PIC]
False: rare. True: rigid ring - one break, no displacement. Pelvic injuries normally when pressure from both sides e.g. jumping from high building.
Pelvic veins = massive hemorrhage. Male urethra - esp in vertical fractures disrupting the urogenital diaphragm. Bladder (behind pubis). Rectum rarely damaged (in sacrum concavity). Nerve injuries follow sacral fractures.
