DSA 4: Intro to Sacrum

Question 1

What is the appearance of the SI joint ligaments in males and females after puberty?

Answer 1

Male: SIJ ligaments are well-developed and strong

Female: SIJ ligaments are less developed, allowing mobility during childbirth

Question 2

What is the appearance of the SI joint in a patient’s 20s?

Answer 2

Crescent-shaped ridge develops along the iliac surface which articulates with a depression in the sacrum

Add stability and limits mobility

Question 3

What is the appearance of the SI joint in a patient’s 30s?

Answer 3

Crescent-shaped ridge becomes more pronounced, decreases ROM more

Males: degenerative changes may begin to appear on iliac side

Question 4

What is the appearance of the SI joint in the 4th and 5th decades of life?

Answer 4

Males: Degenerative changes appear on sacral side

Fibrous ankylosis may further limit joint motion

Question 5

What is the SI joint classified as?

Answer 5

Diarthroidal joint - contanis synovial fluid and matching articular surfaces

Question 6

What ligament is the major bond between the ilium and the sacrum?

Answer 6

Interosseous Sacroiliac Ligament

Question 7

What is the attachment of the long dorsal SI ligament?

Answer 7

PSIS to the lateral aspect of 3rd and 4th sacral segments

Question 8

What are the differential static landmarks for determining sacral sulcus depth?

Answer 8

Medial to the PSIS

Question 9

What is the purpose of the self-locking mechanism of the sacrum?

Answer 9

Resistance against shear

Question 10

What are the two aspects of the sacral self-locking mechanism?

Answer 10

Form closure

Force closure

Question 11

What is form closure of the sacrum due to?

Answer 11

How the joint fits together, specific properties of the articular surfaces of the SI joint

Question 12

What is force closure of the sacrum due to?

Answer 12

Compression produced by body weight, muscles, and ligaments holding it together

Question 13

What are the dorsal muscles that may affect SI joint stability?

Answer 13

Latissimus dorsi

Thoracolumbar fascia

Gluteus maximus

ITB

Question 14

What are the ventral muscles that may affect SI joint stability?

Answer 14

Abdominal obliques

Transverse abdominals

Linea alba (not a muscle but listed on the slide)

Question 15

Where does the Superior Transverse Axis of the sacrum pass through? When would the sacrum move around this axis?

Answer 15

Posterior aspect of S2

Respiratory cycle

Question 16

Where does the Middle Transverse Axis of the sacrum pass through? When would the sacrum move around this axis?

Answer 16

Anterior aspect of S2

Nutation and counternutation in the standing position

Question 17

Where does the Inferior Transverse axis of the sacrum travel through? When would the sacrum move around it?

Answer 17

S3

Axis of movement of ilia on the sacrum

Question 18

As the lumbar spine extends, what is the sacrum doing?

Answer 18

Flexes

Question 19

As the sacrum extends, what is the lumbar spine doing?

Answer 19

Flexion

Question 20

What is the motion of the sacrum in counternutation?

Answer 20

Sacral extension

Question 21

What is the motion of the sacrum in nutation?

Answer 21

Sacral flexion

(Sacrum needs a drink, tilts foward as the “bowl” of the pelvis tips back)

Question 22

Rotation through the lumbar spine causes what movement of the sacrum?

Answer 22

Rotation towards ipsilateral side

Sidebending to contralateral side

Question 23

Downward force of the lumbar spine onto the sacrum causes what motion of the sacrum?

Answer 23

Nutation (sacral flexion)

Question 24

Traction applied from above the lumbosacral junction causes what motion of the sacrum?

Answer 24

Counternutation (sacral extension)

Question 25

Sidebending applied through the lumbar spine causes what motion of the sacrum?

Answer 25

Sidebending to the ipsilateral side

Question 26

What is the relationship of the movements of ilium and sacrum?

Answer 26

Move in the same direction

Question 27

An occipital condylar compression can cause what to occur in the sacrum?

Answer 27

Lowered sacral base on the ipsilateral side

Question 28

What is occurring in this XR?

Answer 28

Lumbarization of S1 May be unilateral or bilateral

Question 29

What is occurring in this XR?

Answer 29

Sacralization of L5 Note: atypically large TPs of L5 Bat wing deformity May be unilateral or bilateral

Question 30

Sacrum dysfunction will commonly manifest as what symptom?

Answer 30

Chronic low back pain

Question 31

What are the two criteria for a compensated lumbar spine?

Answer 31

1. Lumbar spine is rotated toward the deep sulcus (PTP and deep sulcus on the same side) 2. Lumbar spine should be sidebent toward the axis in the case of a torsion

Question 32

What is the position of the compensated L5 for a flexed sacrum?

Answer 32

Neutral (Type 1 spinal mechanics)

Question 33

What is the position of the compensated L5 for an extended sacrum?

Answer 33

Flexed or extended (Type 2 Spinal mechanics)