SIJ iRA/tRA

Question 1

Anterior vs posterior surface of sacrum

Answer 1

anterior - concave, smooth

posterior - convex, rough

Question 2

Where is the sacrum width greater?

Answer 2

Width greater posteriorly at S1, greater anteriorly at S3

Question 3

If lumbosacral angels are decreased that means what?

Answer 3

more direct transfer

Question 4

If lumbosacral angels are increased that means what?

Answer 4

shear on L5/S1

Question 5

function of interosseus sacroiliac ligament

Answer 5

secure bony interlocking, strong bind of sacrum and ilium

Question 6

What prevents anterior separation of the SI joint?

Answer 6

anterior sacroiliac ligament

Question 7

What does the long posterior sacroiliac ligament do?

Answer 7

prevent counter-nutation of sacrum with respect to ilium

Question 8

What does the short posterior sacroiliac ligament do?

Answer 8

prevent posterior flaring/separation of joint

Question 9

function of the sacrospinous ligament

Answer 9

prevent nutation

Question 10

function of the sacrotuberous ligament

Answer 10

prevent nutation

Question 11

muscles that anterior rotate the pelvis

Answer 11

psias/iliacus and rectus femoris

Question 12

muscles that posterior rotate the pelvis

Answer 12

hamstrings

Question 13

action of the piriformis

Answer 13

ER when hips extended

Abduction when hips flexed

Question 14

What does the SIJ tilt forward and downward, rotate around?

Answer 14

Bonnaire’s tubercle

Question 15

What is the function of the SIJ?

Answer 15

• bony locking mechanism
• prevent downward gliding of the sacrum under body weight
• relieves twisting moment on pelvic ring

Question 16

When does elevation and depression of the SIJ develop? What is this good for?

Answer 16

2nd decade
- good for structural stability

Question 17

When does articular cartilage start to decrease depth of surface in SIJ?

Answer 17

8th decade

Question 18

What is nutation? What does this cause the wings to do?

Answer 18

base moves anteriorly and inferiorly and coccyx moves posteriorly
- wings approximate and ischial tuberosity increase in proximity

Question 19

What is counternutation?

Answer 19

base moves superior and posterior and coccyx moves inferior and anterior

Question 20

What is the axis of the SIJ during contralateral prone hip flexion?

Answer 20

pubic symphysis to greater sciatic notch

Question 21

What is the axis of the SIH during contralateral prone hip extension?

Answer 21

pubic symphysis to between ischium and coocyx

Question 22

With extension of the lower limb, the ipsilateral pelvis twists _______

Answer 22

forward
- tension on iliofemoral ligament draws anterior ilium downwards, rotating pelvis

Question 23

With flexion of the LE, ipsilateral pelvis twisted __________

Answer 23

backwards
- tension on hamstrings draws ischium forwards, causing the pelvis to rotate