Week 2- iRA/tRA: Sacroiliac Joint

Question 1

• The sacrum is triangular in shape and is composed of __ fused vertebrae.
• The anterior surface is ______ and _______.
• The posterior surface is _______ and _______.

Answer 1

• 5
• concave and smooth
• convex and rough

Question 2

The sacrum width is greater posteriorly at ___ and greater anteriorly at ___.

Answer 2

-S1, S3

Question 3

The sacrum has sinuous surfaces with depressions/elevations that aid in bony congruency, what 2 things does this help with?

Answer 3

1. ) Depression ~S2 to accept Bonnaire’s tubercle from ilium.
2. ) Prevent downward gliding of sacrum.

Question 4

How thick is the hyaline cartilage of the sacrum?

Answer 4

-1-3mm

Question 5

What are the (3) parts of the hip?

Answer 5

• llium
• Pubis
• Ischium

Question 6

What are the functions of the sacrum?

Answer 6

• Supports lumbar spine.

- Transmits loads from LEs to vertebral column. (sideways into pelvis as well)

Question 7

Lumbosacral Angles:

• Horizontal and line passing through upper border of S1 = _____ degrees
• L1-S1 Lordosis angle = ____ degrees
• Lumbosacral disc angle = ____ degrees

Answer 7

• ~50 degrees
• ~70 degrees (planes of superior S1 and L1 surfaces)
• ~16 degrees (bottom surface of L5 and top surface of S1)

Question 8

• If the lumbosacral angles are decreased, what happens?

- If the lumbosacral angles are increased what happens?

Answer 8

• More direct transfer

- Shear of L5/S1

Question 9

Ligaments of the SI joint assist in locking _____ at SIJ.

Answer 9

-ilia

Question 10

What are the (7) ligaments of the SIJ?

Answer 10

• Interosseous SI ligament
• Anterior SI ligament
• Posterior SI ligament
• Long Posterior SI ligament
• Short Posterior SI ligament
• Sacrospinous ligament
• Sacrotuberous ligament

Question 11

The Interosseous SI ligament is located dorsal to cavity of joint and has inferior and superior bands. What is its function?

Answer 11

-Secure bony interlocking, strong bind of sacrum and ilium

Question 12

The Anterior SI ligament covers the ventral joint. What is its function?

Answer 12

-Prevents anterior separation of joint.

Question 13

The Long Posterior SI ligament is more longitudinal in orientation and has what function?

Answer 13

-Prevent counter-nutation of sacrum with respect to ilium.

Question 14

What is the function of the Short Posterior SI ligament?

Answer 14

-Prevent posterior flaring/separation of joint.

Question 15

What is the function of the Sacrospinous ligament?

Answer 15

-Prevent nutation.

Question 16

What is the function of the Sacrotuberous ligament?

Answer 16

-Prevent nutation.

Question 17

What are the 4 main muscles that act on the SIJ and their function?

Answer 17

• Hamstrings = Posterior rotation of pelvis-extension of sacrotuberous ligament; sacrospinous ligament placed on stress.
• Psoas/Iliacus = Anterior rotation of pelvis.
• Rectus Femoris = Anterior rotation of pelvis.
• Piriformis = ER in extension position of hips, abducts hip when positioned in hip flexion.

Question 18

Transverse Abdominis (TrA):

• Origin = ________
• ____-________ mechanism of TrA
• Reduced vertical SIJ shear

Answer 18

• inguinal ligament, anterior 2/3 iliac crest, thoracolumbar fascia, lower (6) costal cartilages
• Feed-forward

Question 19

Pelvic floor muscles oppose lateral movement of the _______ bones and stabilizes the sacrum between ______ bones.

Answer 19

-coxal

Question 20

• The SIJ is innervated posteriorly by dorsal rami ___-___ and anteriorly by ___-____, superior gluteal nerve, obturator nerve.
• The SIJ tilts forward and downward; rotates around ________ tubercle.

Answer 20

• L4-S2, L2-S2

- Bonnaire’s

Question 21

What are the (3) functions of the SIJ?

Answer 21

• Bony locking mechanism.
• Prevent downward gliding of the sacrum under body weight.
• Relieves twisting moment on pelvic ring.

Question 22

SIJ Lifespan:

• Fetal Development
  
  • ___ month = SIJ first appearance
  • ___ month = cavitation full
  • ___ weeks = synovial membrane
• First 10 years (joint enlarges)
  
  • surfaces remain _____
  • ______ capsule thickens
• 2nd decade (corrugation of joint)
  
  • ________ along articular surface w/ ridge of ilium

Answer 22

• 2nd month
• 7th month
• 37 weeks
• flat
• anterior

-depression

Question 23

SIJ Lifespan:

• 3rd to 6th decade
  
  • Superficial fibrilation and erosion on _____ side
  • capsule and synovium become more ______
  • ________ development
  • debris and fibrous tissue fill joint cavity
• 8th decade
  
  • inter-articular fibrous ________ common
  • articular cartilage

Answer 23

• iliac
• fibrous
• osteophyte
• adhesions
• <1mm on sacrum, <0.5mm on ilium

Question 24

• ________ = Base moves anteriorly and inferiorly, apex and coccyx move posteriorly.
• ________ = Base moves superior and posterior, apex and coccyx move inferior and anterior.
• What is the axis of rotation?
• What theory is this?

Answer 24

• Nutation
• Counternutation
• interosseous ligament
• Farabeuf Theory

Question 25

What does Bonnaires's Theory say?

Answer 25

-Center of motion intra-articular.

Question 26

Axis of the SIJ pass obliquely across the pelvis. - Flexion: pubic symphysis to _____________ - Extension: pubic symphysis to between ________ and ______

Answer 26

- greater sciatic notch | - between ischium and coccyx

Question 27

What is the function of the SIJ?

Answer 27

-Relieves stress on pelvic ring.

Question 28

Are there any muscles designed to produce active physiological movement of the SIJ?

Answer 28

No, all muscles are designed to act on hip and lumbar spine.

Question 29

Ambulation: - With extension of the lower limb, the ipsilateral pelvis twists ________. - With flexion of the lower limb, ipsilateral pelvis twisted _________. - Twisting forces are absorbed by _______.

Answer 29

- forward - backwards - ligaments

Question 30

What are the "3 Types" of SIJ?

Answer 30

- Normal - "High-up" - Low-down"

Question 31

Normal -Sacra showing an auricular surface extending from the ___ to the middle of the ___ sacral segments. "High-up" - Stable ____ segments - Force transmitted at ______ vertebral levels "Low-down" - Stable at _____ segments - Force transmitted through _______ segments - Diminished need for complete fusion of the S1 segment

Answer 31

-S1, S3 - upper - upper - lower - lower