Sacrum Flashcards
The sacral promontory is the anterior portion of ____
S1
ILA =
Inferior lateral angle (of the sacrum)
Do any muscles move the sacrum directly?
No! “The sacrum is mostly a stabilizer, an anchor, a foundation…”
List the muscles/connections of the sacrum:
Piriformis (2nd-4th sacral segments)
Iliacus (superolaterally)
Pelvic diaphragm (particularly coccygeus, anteriorly to sacrotuberous &sacrospinous ligaments)
Aponeurosis of the erector spinae and Latisimus dorsi (posterior-medial surface)
Gluteus Maximus (ILA)
Function/innervation of the piriformis:
Externally rotates, slight extension, and abductor of the hip when the hip is flexed; S1/2
Lumbosacral angle (aka Ferguson’s angle) details:
The angle is generally between 25-35 degrees
An increase in this angle can increase lumbosacral strain
Two main landmarks for sacral diagnosis:
Sacral sulci (slightly medial and superior to the PSIS’s) and the ILA (most posterior/inferior aspect of sacrum, attachment of gluteus maximus)
L5 rule in Anglund’s terms
“the concept that L5 and the sacrum rotate in opposite directions”
Describe the seven axes of sacral motion:
1 vertical: allows for left/right rotation
1 Anterior-posterior: allows for sidebending
3 Transverse: Allows for flexion and extension.
2 oblique axes: Combines rotation, sidebending, and flexion/extension.
Describe the superior transverse axis (thoracic respiratory axis)
S1/S2 interspace
Flexion and Extension occurs with respiration:
The sacrum flexes with exhalation
The sacrum extends with inhalation
Describe the middle transverse axis (postural or sacroiliac axis)
Level of S2, at the anterior convexity of the upper and lower limbs of SI joint
Flexion and extension occurs with motion of the sacrum on the ilium
Describe the inferior transverse axis (iliosacral axes) (3 of them)
Located at level of S3, at the posterior-inferior part of the inferior limb of SI joint
Flexion and extension occurs with motion of the ilium on the sacrum
All three of the transverse axes allow for what (bottom line)?
Flexion and extension
Oblique sacral axes are named for the _______ aspect
superior
“when you have a left axis, the ______ _______ is moving”
right base
The lumbar spine sidebends _______ to the weighted foot
ipsilateral (due to QL contraction)
Describe SI joint dysfunction and inhibition of the glut max and medius
This shortens the stride… the hamstrings are the recruited and overused to help extend the hip and leg… the erector spinae are also recruited and overused
What is the L5 rule?
In sacral torsion, the sacrum and L5 rotate opposite each other
Describe forward sacral torsions (Type I)
These occur with NEUTRAL mechanics in the lumbar spine
Describe backward sacral torsions (Type II)
These occur with NON-Neutral mechanics in the lumbar spine
In a left on left sacral torsion, it is expected that L5 is rotated to the ______ and side bent _____
R right, SB left
A positive spring test will always give you a _______ problem.
posterior
If forward motion of the sacral base is present, the spring test would be _______
negative
