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19 Cards in this Set
- Front
- Back
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What type of joint is the SI? What is the shape of the articular surface?
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Synovial, auricular shape
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What are the intra-articular and extra-articular ligaments of the SI joint?
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Intra-articular: Interosseous
Extra-articular: Sacrospinous, sacrotuberous, iliolumbar, long posterior |
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What are the characteristics of the symphysis pubis?
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- Plane joint
- Small synovial disc - Withstands significant forces |
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What are the characteristics of the sacrococcygeal joint?
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- Small joint
- Attachment for pelvic floor muscles and SI ligaments - Vulnerable to injury |
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What is form vs. force closure? What is the SI joint?
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- Form closure: Ligaments, joint, cartilage
- Force closure: Muscles - SI mechanics rely on both |
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What does the SI joint axis look like?
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Oblique joint axis
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What is sacral motion driven by? What are the motions called?
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- Driven by axial skeleton (spine)
- Nutation = sacral flexion - Counternutation = sacral extension |
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What is innominate motion driven by? What are the motions called?
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- Driven by appendicular skeleton (hip)
- Anterior rotation of innominate (CN of sacrum) - Posterior rotation of innnominate (N of sacrum) |
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How does trunk FB affect the SI joint?
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- Early range: Sacral N (anterior rotation of innominate)
- Late range: Sacral CN (posterior rotation of innominate) - SI becomes unstable |
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How does trunk BB affect the SI joint?
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- Early range: Sacral CN
- Late range: Sacral N (depends on total mobility) |
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What is the effect of hip flexion and extension on SI motion?
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- Hip flexion: Posterior rotation of innominate
- Hip extension: Anterior rotation of innominate |
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What is ankylosis? Who does it affect most?
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- Non-pathologic aging
- Occurs especially in males > 40 yo |
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What muscles cause force closure of the SI joint?
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- Transversely oriented muscles: Pelvic floor, transverse abdominus, internal oblique
- Those crossing the pelvis: Muscle, ligament, fascia interaction |
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What are the core local muscles (inner muscle chain) of the SI joint?
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- Diaphragm
- Multifidus - Transversus abdominis (transversely oriented) - Pelvic floor (transversely oriented) |
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What are the four outer muscle chains of the SI joint?
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1. Posterior oblique
2. Deep longitudinal 3. Anterior oblique 4. Lateral muscle chain |
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What are the muscles of the posterior oblique muscle chain? What do they control?
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- Gluteus maximus
- Latissimus (contralateral) - Lumbodorsal fascia - Control frontal and transverse planes |
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What are the muscles of the deep longitudinal chain?
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- Biceps femoris
- Sacrotuberous - Lubodorsal fascia (deep) - Erector spinae |
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What are the muscles of the anterior oblique chain? What do they control?
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- External obliques
- Internal obliques (contralateral) - Adductors (contralateral) - Control frontal and transverse planes |
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What are the muscles of the lateral muscular chain? What do they control?
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- Gluteus medius/minimus
- Adductors (contralateral) - Control frontal plane |
