SI Joint Anatomy

Question 1

SI related Sx’s are ____

Answer 1

• common
• Often difficult to Dx due to overlap with many other stuctures

Question 2

SI is a real and fairly common contributor to ____

Answer 2

LBP

Question 3

What is the shape of the pelvic bones called?

Answer 3

Pelvic Ring

Question 4

How does anatomy contribute to Spondylolithesis occuring in some individuals?

Answer 4

• The angle of the L5 vertebrae and angle of the Sacrum is very sharp. This tipping angle contributes to the higher chance of the forces creating the seperation to occur.

Question 5

How are the sacrum facets facing?

Answer 5

• Frontal Plane Alignment similar to thoracic spine

Question 6

Why is the auricular pillar important?

Answer 6

• Portion of the sacrum that connect to the pelvis; where movement occurs
• Ear shape

Question 7

The SI Joint is very well supported by ____

Answer 7

ligaments

Specifically…
* Sacrotuberous: Inferior Lateral Angle to Ischial Tuberosity
* Sacrospinous: ILA to Ischial spine
* Posterior SI: SI ligaments long and short

Question 8

Important Muscles for the SI

Answer 8

• Erector Spinae
• Quadratus Lumborum
• Mulifidus
• Thoracolumbar fascia
• Latissimus dorsi
• Pelvic Floor Muscles

Question 9

What levels innervate the SI Joint?

Answer 9

• L3 to S4
• This is why it is difficult to determine the specific cause of issues
• Note: position of sympathetic chain