SIJ Flashcards
What is the purpose of the sacrum
provides stability and transmits BW from vertebral column to pelvic region
What is the sacral cornua
bilat downward projections
What is the median sacral crest?
midline; fusion of SP S1-S4
What is the intermediate sacral crest
fused laminae S1-S5
What is an innominate
2 hip bones fused together
Where do the innominates fuse
acetabulum
Which is the “short” SI lig? What type of lig
interosseous; articular
Which is the long SI lig? what type of lig?
posterior (dorsal); articular?
What type of lig is sacrotuberous lig?
extra articular
Where is interosseous SI lig located? fxn?
-between sacrum and innominate
-fxn: resists anterior and inferior movement of sacrum
What structures does the posterior SI lig connect?
PSIS, lat crest of 3-4 seg of sacrum
What structures are connected by sacrotuberous lig?
ischial tub, piriformis, transverse tubercles of S3-S5, coccyx, glute max
Fxn of sacrotuberous lig?
-stabilizes against nutation of sacrum
-counteracts against pot and superior migration of sacral apex during WB
What is SIJ essential for?
shock absorption during WB acts
What two structures facilitate SIJ motion?
pubic symphysis, fibrocartilaginous surfaces of innominate facets
What is nutation?
closed pack position or self locking mech of SIJ
What is nutation most effective for?
transferring high loads
What does counternutation do?
-reduces self locking mech
-increases intervertebral disc pressure
