sacrum Flashcards
weight of upper body transmitted through sacrum and which ligaments?
- iliolumbar
- sacrospinous
- sacrotuberous
which ligaments connect sacrum to pelvis?
- ant and post SI ligaments
- extremely strong
what is the 1st ligament to spasm when there is a sacrum dysfx?
iliolumbar ligament
mm of the sacrum
- piriformis
- iliacus
- pelvic diaphragm (coccygeous)
- aponeurosis of erector spinae and lat
- gluteus maximus
piriformis attachments
- origin: S2-4
- insert: greater trochanter
piriformis action
- external rotation of thigh
- abductor of the hip when the hip is flexed
piriformis innervation
S1-2
piriformis impt
sacral dysfx can lead to piriformis syndrome
lumbosacral angle (Ferfuson’s angle)
- 25-35 degrees
- angle increase due to increase lumbosacral strain
7 axes of motion of sacrum
- 1 vertical: L/R rotation
- 1 ant/post: sidebending
- 3 transverse: flexion and extension
- 2 oblique: combines all of the above motions
superior transverse/ resp axis
- S2
- flexion and ext occurs with resp (flex-exhale; extend-inhale)
middle transverse/ postural/SI axis
- S2
- at ant convexity of upper and lower limbs of SI joint
- flex and ext occurs with motion of the sacrum on the ilium
inferior transverse/iliosacral axes
- S3
- at post-inf part of the inf limb of SI joint
- flex and ext occurs with motion of ilium on sacrum
oblique sacral axes
- named for superior aspect and goes to contralat
dynamic sacral motion - gait cycle: walking
sacrum alt: R-on-R, neutral, L-on-L, neutral
dynamic sacral motion - gait cycle: stance phase
- ipsilat oblique axis is created, and the sacrum moves ant (obliquely) about this axis
- lumbar spine sidebends ipsilat to the weighted foot because of quadratus lumborum contraction
L stance: what sacral motion occurs?
- R-on-R sacral torsion
- lumbar sidebending R
SI joint dysfx
- inhibit glut max and medius
- QL inhibit
- disrupt fascial connection from foot into TL region
inhibited glut max and medius cause?
- shortens stride
- hamstrings recruited and overused to help extend the hip and leg
- erector spinae recruited and overused
spasm of QL cause?
- LBP
- can be activated by standing on the same leg constantly or by jumping and landing on the same leg multiple times
disruption of fascial connection from foot into TL region
gait abnormalities
L5 rule
- sacrum and L5 rotate opposite each other
forward sacral torsion occurs with what lumbar SD?
- neutral mech (type 1)
backward sacral torsion occur with what lumbar SD?
- non-neutral mech (type 2)
L-on-L sacral torsion
what lumbar SD?
L5 NRRSL
tests to dx sacrum
- seated flexion
- sphinx
- landmarks: deep sacral sulcus and ILA
- motion testing
b/l sacral shear
- neg seated flexion test
- exaggeration of normal flex or ext
- sacral sulci equal but excessively deep or shallow
- ILA equal but excessively deep or shallow
