Week 2- iRA/tRA: Sacroiliac Joint Flashcards
- The sacrum is triangular in shape and is composed of __ fused vertebrae.
- The anterior surface is ______ and _______.
- The posterior surface is _______ and _______.
- 5
- concave and smooth
- convex and rough
The sacrum width is greater posteriorly at ___ and greater anteriorly at ___.
-S1, S3
The sacrum has sinuous surfaces with depressions/elevations that aid in bony congruency, what 2 things does this help with?
- ) Depression ~S2 to accept Bonnaire’s tubercle from ilium.
- ) Prevent downward gliding of sacrum.
How thick is the hyaline cartilage of the sacrum?
-1-3mm
What are the (3) parts of the hip?
- llium
- Pubis
- Ischium
What are the functions of the sacrum?
- Supports lumbar spine.
- Transmits loads from LEs to vertebral column. (sideways into pelvis as well)
Lumbosacral Angles:
- Horizontal and line passing through upper border of S1 = _____ degrees
- L1-S1 Lordosis angle = ____ degrees
- Lumbosacral disc angle = ____ degrees
- ~50 degrees
- ~70 degrees (planes of superior S1 and L1 surfaces)
- ~16 degrees (bottom surface of L5 and top surface of S1)
- If the lumbosacral angles are decreased, what happens?
- If the lumbosacral angles are increased what happens?
- More direct transfer
- Shear of L5/S1
Ligaments of the SI joint assist in locking _____ at SIJ.
-ilia
What are the (7) ligaments of the SIJ?
- Interosseous SI ligament
- Anterior SI ligament
- Posterior SI ligament
- Long Posterior SI ligament
- Short Posterior SI ligament
- Sacrospinous ligament
- Sacrotuberous ligament
The Interosseous SI ligament is located dorsal to cavity of joint and has inferior and superior bands. What is its function?
-Secure bony interlocking, strong bind of sacrum and ilium
The Anterior SI ligament covers the ventral joint. What is its function?
-Prevents anterior separation of joint.
The Long Posterior SI ligament is more longitudinal in orientation and has what function?
-Prevent counter-nutation of sacrum with respect to ilium.
What is the function of the Short Posterior SI ligament?
-Prevent posterior flaring/separation of joint.
What is the function of the Sacrospinous ligament?
-Prevent nutation.
What is the function of the Sacrotuberous ligament?
-Prevent nutation.
What are the 4 main muscles that act on the SIJ and their function?
- 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.
Transverse Abdominis (TrA):
- Origin = ________
- ____-________ mechanism of TrA
- Reduced vertical SIJ shear
- inguinal ligament, anterior 2/3 iliac crest, thoracolumbar fascia, lower (6) costal cartilages
- Feed-forward
Pelvic floor muscles oppose lateral movement of the _______ bones and stabilizes the sacrum between ______ bones.
-coxal
- 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.
- L4-S2, L2-S2
- Bonnaire’s
What are the (3) functions of the SIJ?
- Bony locking mechanism.
- Prevent downward gliding of the sacrum under body weight.
- Relieves twisting moment on pelvic ring.
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
- 2nd month
- 7th month
- 37 weeks
- flat
- anterior
-depression
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
- iliac
- fibrous
- osteophyte
- adhesions
- <1mm on sacrum, <0.5mm on ilium
- ________ = 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?
- Nutation
- Counternutation
- interosseous ligament
- Farabeuf Theory
What does Bonnaires’s Theory say?
-Center of motion intra-articular.
Axis of the SIJ pass obliquely across the pelvis.
- Flexion: pubic symphysis to _____________
- Extension: pubic symphysis to between ________ and ______
- greater sciatic notch
- between ischium and coccyx
What is the function of the SIJ?
-Relieves stress on pelvic ring.
Are there any muscles designed to produce active physiological movement of the SIJ?
No, all muscles are designed to act on hip and lumbar spine.
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 _______.
- forward
- backwards
- ligaments
What are the “3 Types” of SIJ?
- Normal
- “High-up”
- Low-down”
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
-S1, S3
- upper
- upper
- lower
- lower
