SI joint and Axial Skeleton Muscle and Joint Interactions

Question 1

What is the sacroiliac joint?

Answer 1

Junction between auricular surfaces of the sacrum and ilium, tight fitting for stability

Question 2

What is the keystone of the pelvic ring?

Answer 2

The sacrum

Question 3

Where is the sacrum located anatomically?

Answer 3

Wedged between the two ilia and secured bilaterally by the sacroiliac joints

Question 4

What do the sacroiliac joints do?

Answer 4

transfer the weight of the upper body to the LE, shock absorber with heel pcontact

Question 5

What percentage of LBP is from the SIJ as a origin?

Answer 5

~25%

Question 6

What happens if leg length is not equal by 1 cm?

Answer 6

5X increased compression at the SIJ on the longer side

Question 7

What does the anterior sacroiliac ligament do?

Answer 7

Thickening of the capsule

Question 8

What does the iliolumbar ligament do?

Answer 8

Stabilizer of lumbosacral joint and SIJ

Question 9

What does the Interosseous ligament do?

Answer 9

Fills the gap, strong like a syndesmosis at tib/fib

Question 10

What does the sacrotuberous ligament do?

Answer 10

Blends with biceps femoris - broad attachment

Question 11

Where does the sacrospinous ligament run?

Answer 11

Sacrum to ischial spine

Question 12

What is the primary passive stabilizer for the SI joint?

Answer 12

Pelvic girdle ligaments

Question 13

What SIJ innervation can cause pain?

Answer 13

Not clear the level, L5-S3 spinal nerve roots usually and less often L4-S2

Question 14

Where can pain locations from the SIJ innervation be?

Answer 14

Ipsilateral lower lumbar region, medial buttock, PSIS, and along short and long SIJ ligs

Question 15

What is the role of the thoracolumbar fascia?

Answer 15

An important role in mechanical stability of the low back and SIj

Question 16

Where is the thoracolumbar fascia most extensive?

Answer 16

In the lower back, surrounds various muscle groups

Question 17

Where is the sacral sulcus?

Answer 17

PSIS and up a tad superiorly and will feel a dip in, this is how we monitor the base of the sacrum

Question 18

What is the sacral sit test?

Answer 18

Patient sits with your thumbs on their PSIS while they flex, both should move in a symmetrical position

Question 19

What is the Sphinx test?

Answer 19

Patient is prone, comes up to elbows, you monitor sacral sulcus and ILAs to assess sacrum

Question 20

What does ILA stand for?

Answer 20

Inferior lateral angles

Question 21

How can we describe the sacral joint surface?

Answer 21

ear-shaped or L-shaped; vertical short arm and more horizontal long arm

Question 22

What kind of cartilage is sacral articular cartilage?

Answer 22

White and smooth hyaline - from 1-3 mm

Question 23

What prevents downward gliding of the sacrum?

Answer 23

Irregular ridges and depressions on the sacral joint surface that are matched by reciprocal shapes on the ilium, which interlock in contours

Question 24

Why are the contours of the sacral joint surface variable?

Answer 24

Depending on age

Question 25

The articular surface of the sacrum is twisted from _______ downwards

Answer 25

From above downwards like a propeller

Question 26

The ilia side of the SIJ is also cartilage. What kind?

Answer 26

Fibrocartilage 1-2mm thickness

Question 27

What kind of joint is the SIJ?

Answer 27

Synovial joint

Question 28

What are the two layers of the joint capsule of the SIJ?

Answer 28

External fibrous layer and inner synovial layer

Question 29

Can we palpate the SIJ depth?

Answer 29

NO

Question 30

What is different about the SIJ in early life?

Answer 30

Surfaces generally flat

Question 31

What is different about the SIJ during puberty?

Answer 31

Surfaces develop ridges/grooves and enhance stability

Question 32

What are the osteo/arthrokinematics of the iliac crests on the sacrum?

Answer 32

Iliac crests move on the sacrum = innominate motion/iliosacral

Question 33

What are the osteo/arthrokinematics of the sacrum on the iliac crests?

Answer 33

Sacrum moves on innominates = sacroiliac motion

Question 34

How much posterior rotation of the SIJ when NWB?

Answer 34

10-12 degrees innominate posterior rotation couples with 6mm anterior translation

Question 35

How much anterior rotation of the SIJ with NWB?

Answer 35

2 degrees innominate anterior rotation coupled with 8mm anterior translation

Question 36

How much innominate rotation of the SIJ when WB?

Answer 36

2.5 degrees innominate rotation and 0.5-1.6mm translation

Question 37

When does motion at the SIJ occur?

Answer 37

During movements of the trunk and extremities

Question 38

What are the 3 planes of motion at the SIJ?

Answer 38

FLX/EXT, Lateral flexion, rotation

Question 39

How many degrees for rotation at SIJ? Translation?

Answer 39

2-4 degrees for rotation and 1-2mm translation

Question 40

What is the closed packed position of the SIJ?

Answer 40

Full nutation (flexion), standing when loaded, gravity/ligs/muscles

Question 41

When is the SIJ unloaded?

Answer 41

When supine, sacrum tends to return to counternutation or less stable

Question 42

What does nutation mean?

Answer 42

Nodding

Question 43

When does bilateral movement of the sacrum occur?

Answer 43

With forward/backwards bending of the trunk

Question 44

When does unilateral motion of the sacrum occur?

Answer 44

With flexion/extension of the LEs

Question 45

What is sacral nutation relative to the innominates?

Answer 45

The forward motion of the sacral promontory into the pelvis on the coronal axis; anteriorly and inferiorly - glides inferiorly down the short arm and posteriorly along the long arm

Question 46

What is sacral nutation resisted by?

Answer 46

Wedge shape of sacrum, ridges/depressions in joint surface, interosseous and sacrotuberous ligaments

Question 47

What is sacral counternutation relative to the innominates?

Answer 47

Sacral base moves posteriorly and superiorly; glides anteriorly along long arm and superiorly up short arm

Question 48

What is sacral counternutation resisted by?

Answer 48

Long dorsal ligament

Question 49

Why is sacral counternutation considered less stable?

Answer 49

Because ST and Interosseous ligaments are lax

Question 50

What does the sacrum do with forward bend?

Answer 50

Sacrum counternutates

Question 51

What does the sacrum do with lumbar extension?

Answer 51

Sacrum nutates

Question 52

During gait, what does the sacrum do?

Answer 52

One side nutates with side bend and induces rotation, which becomes a coupled motion called sacral torsion

Question 53

What is the superior axis used for?

Answer 53

Breathing - inhale base forward and coccys/ILA posterior; L/S flexes; reverses with exhale

Question 54

What is the middle axis used for?

Answer 54

Nutation (flexion) and counternutation (extension); postural

Question 55

What is the inferior transverse axis used for?

Answer 55

Ilia on sacral movements

Question 56

What is the vertical axis used for?

Answer 56

Unilateral rotation

Question 57

What are torsions?

Answer 57

Motions or can be a dysfunction /sacrum in a 'stuck' position

Question 58

What are the two types of torsions?

Answer 58

physiological motions non physiological motions

Question 59

What are physiological motion?

Answer 59

anterior motion fixation/ nutation

Question 60

What are non-physiological motions?

Answer 60

Posterior motion fixation/counter-nutation

Question 61

What are the two types of physiological motions?

Answer 61

1.) L on L (look left and nutates) 2.) R on R (look right and nutates)

Question 62

What are the two types of non-physiologcial motions?

Answer 62

3.) L on R ( comes backwards, looks left because rotates on right axis) 4.) R on L (sacrum tips back to look right, moves on left axis)

Question 63

Which types of torsion is painful?

Answer 63

Non-physiological

Question 64

What kind of torsion does not occur in the normal gait cycle?

Answer 64

Posterior nutational movement

Question 65

In the normal walking cycle, what torsion DOES happen?

Answer 65

The sacrum appears to move with left torsion on the left oblique axis, return to neutral, rotate in right torsion on the right oblique axis and then return to normal