Sacrum DSA

Question 1

What is needed for resistance against shear?

Answer 1

Form closure and force closure

Question 2

form closure vs force closure?

Answer 2

form

• specific properties of articular surfaces of SIJ (how it fits together)
• proper size, shape, and attitude of articulating surfaces

force

• compression produce by body weight, m action, and ligament force
• m, fascia, ligaments, gravity and loading forces

Question 3

What can affect SI joint mobility?

Answer 3

postural m

posterior: lats, TL fascia, gluteus maximus, ITB
anteriorly: abd m, linea alba, transverse abd

Question 4

What way does the lumbar spine move in respect to the sacral base and apex?

Answer 4

moves in the same direction as the apex and opposite direction of the base

Question 5

what does counternutation and nutation mean?

Answer 5

counternutation - sacral extension

nutation - sacral flexion

Question 6

downward force from lumbar region causes the sacrum to move how?

traction from LS junction causes the sacrum to move in what way?

Answer 6

downward force - sacrum downward and cause nutation

traction force - sacrum up and counternutation

Question 7

a restricted inferior occipital condylar part is related to what?

Answer 7

a lowered sacral base on that side

Question 8

lumbarization vs sacralization

Answer 8

S1 becomes like an additional lumbar vertebra

sacralization: incomplete separation of L5, characteristics of sacral vertebra

Question 9

sacralization can lead to what?

Answer 9

batwing deformity (if bilateral)

pseudoarthrosis w sacrum/ilium from larger L5 TP