Sacrum Flashcards
when does sacrum fuse?
around the age of 25
- in its center is the sacral canal with the caudaequina and 4 sacral spinal nn. which exit from the sacral foramina
- top of sacrum is the base: the bottom of the sacrum is the apex
What muscles move the sacrum?
none directly move the sacrum- possibly piriformis (attaches to 2-4th sacral segments) - externally rotates leg when hip is in flexion
Piriformis
Attachments:S2-4 and inserts into the greater trochanter of the femur
Action:External rot of thigh; abductor of the hip when the hip is flexed
Innervation: S1-2*** Sciatic n. often passes through the piriformis, or over piriformis, or splits through piriformis: can result in sciatica
landmarks of sacrum? how do you find sacral sulci?
sacral sulci: found medial and slightly superior to PSIS
Physician places the palm of his/her hand on the sacrum. The most posterior aspect of the sacrum is the level of the Inferior Lateral Angles. The thumbs are then placed on each ILA.
7 axes of sacral motion?
vertical axis: allows for left/right rotation (“queens wave”)
Anterior-posterior axis: allows for sidebending (small motion)\
Transverse axes (3): Allows for flexion and extension.
oblique axes (2): Combines rotation and sidebending.
- Right oblique axis
- Left oblique axis
Transverse Axes:
- Respiratory axis (superior transverse axis) - S2
- Sacroiliac axis (middle transverse axis) - S2 = postural
- Iliosacral axis (inferior transverse axis)Anteroposterior axis- S3 = rotational
superior transverse/respiratory axis
Superior transverse / Respiratory axis.
(S2)- Flexion and Extension occurs with respiration.- The sacrum flexes when lumbar lordosis increases (exhalation)- The sacrum extends when lumbar lordosis decreases (inhalation)
Sacroiliac (sacrum on ilium)/middle transverse
S2/ S3 = rotational
Flexion and extension occurs with motion of the sacrum on the illium.
Oblique sacral axes
Named for the SUPERIOR aspect they exit.
The axis that runs from the right inferior aspect of the sacrum(right ILA) to the left superior aspect of the sacrum(left sacral sulcus) is the left oblique axis.
The axis that runs from the left inferior aspect of the sacrum(left ILA) to the right superior aspect of the sacrum(right sacral sulcus) is the right oblique axis.
Iliosacral (ilium on sacrum)/inferior transverse
S3/S4 = rotational
Flexion and extension occurs with motion of the ilium on the sacrum.
L5 Rules/Sacral Torsion rules (always true for high yield exam)
- The sacral oblique axis will be to the same side as L5 side bending- So if L5 is FRSL then the sacral axis will be left
- The sacrum rotates opposite of L5- So if L5 is FRSL then the sacrum will rotate right (R on L)
- The seated flexion test is positive on the opposite side of the oblique axis - So +SeFT on the right, we will have a left oblique axis
What is dynamic sacral motion with walking?
Torsional motion occurs during the walking cycle, depending on which phase of gait we are in. When we place weight on our left foot the sacrum rotates to the Right, on the Right oblique axis at midstance.The lumbar spine sidebends Right because of QL contraction.This motion is normal, however, when this motion is limited or fixed in a non-neutral position dysfunction occurs.
What does sacrum do in gait?
For right leg stride
Right heel strike & propellant stance (foot flat)- Sacrum is symmetrical
At ballistic stance (midstance)- Left on left sacral torsion
At bipedal support (toe-off) & right initial swing (acel) = Sacrum is symmetrical
At midswing = Right on right sacral torsion
At right terminal swing = Sacrum symmetrical
Seated flexion test
- Seated flexion test determines the motion of the sacrum upon the ilium. (sacroilial, S3 axis)
- The side which is positive is usually the side of dysfunction (and opposite the axis)
- in sacral torsions. False positives exist due to muscle influences.
positive sacral flexion test?
The side which is positive is usually the side of dysfunction (and opposite the axis)in sacral torsions.
sacral sheers = same side of dysfunction
sacral torsions = opposite the axis
Lumbar spring test
The Spring test determines if the base of the sacrum is able to move FORWARD or if it is stuck BACKWARDS.A board like resistance or “lack of spring” to the LS junction determines that the sacrum is stuck BACKWARDS. This is a positive Spring Test.
Backwards bending test (Sphinx test) = BBT
This creates lumbar extension and sacral flexion.If the findings improve the sacrum likes flexion and the direction of ease of the SD is forward.This is a NEGATIVE BBTIf they get worse, this is a + BBT
Naming sacral torsion
- Rotation is stated first with the axis stated 2nd
.i.e. For example, a right rotation on a right axis: R on R
unilateral sacral flexion/extension
= “shear”… the slippage of one SI joint about a vertical axis
- will see opposites on sulcus and ILA of same side.
- named for the side of the seated flexion test
bilateral sacral flexion/extension
= bilateral shear
- sacral sulcus is equal but excessively deep/shallow on both sides
- will have negative seated flexion test
+ spring = bilateral sacral extension
exhalation and inhalation movements
inhalation –> extension
exhalation –> flexion of sacrum
ddx of sacrum?
- perform seated flexion test
(false positive muscles: ipsilateral quadratus lumborum pulls innom up, contralateral gluteus medus holds the opposite innominate down) - perform pelvic compression side: whicever side is restricted is dysfunctional
- assess sacral sulci and ILAs
perform backward bending test (if sacrum prefers flexion then the asymmetry of ILAs should improve) - perform spring test (if there is movement, then sacrum prefers flexion and test is negative)
L5 NSLRR = ?
L on L
L5 FRSL
R on L
deep bilateral sacral sulcus, - spring test, less pain with BBT?
bilateral sacral flexion
shallow b/l sacral sulcus, + spring test, more pain with BBT?
bilateral sacral extension
+ right, deep right sulcus, deep left ILA, improved BBT, - spring test
Shear: unilateral right flexed sacrum
+ Left, deep right sulcus, deep left ILA, no improved BBT, + spring test
Shear: unilateral left extended sacrum
+ right, deep right sulcus, deep right ILA (improved BBT, - spring test)
Torsion: L on L
+ left, deep right sulcus, deep right ILA (no improvement with BBT, + spring test)
Torsion: L on R
+ Left, deep left sulcus, deep right ILA
Shear: unilateral left flexed sacrum
+ right, deep left sulcus, deep right ILA
Shear: unilateral right extended sacrum
+ left, deep left sulcus and ILA (- spring test)
torsion: R on R
+ right, deep left sulcus and ILA (+ spring test)
torsion: R on L
MET for bilaterally flexed sacrum
abduct legs to obtain gapping of SI joint
- place both hands over sacral apex
- instruct patient to inhale and old breath in inhalation (causing sacral extension)
- instruct patient to relax and breath
MET for bilaterally extended sacrum
abduct both legs while patient lying prone
place thenar eminance over sacral base
instruct patient to hold exhalation while you resist sacral extension, allow patient to relax and breath
MET for unilateral sacral flexion
patient lies prone, abduct and internally rotate hip (flex right knee to 90 degrees and bring ankle laterally with caudal hand to get internal rotation of hip)
- place hand over eminance of the ILA that you are treating
- instruct patient to hold breath in inhalation (inducing sacral extension), while keeping dowward force
- instruct patient to relax and breath and resist motion
MET for unilateral sacral extension
patient is lying prone, abduct and internally rotate right hip (may flex knee 90 degrees, and bring ankle out laterally)
- place thenar eminence on sacral base of affected side
- instruct patient to hold breath on deep exhalation, while exerting doward force, maintain pressure and instruct patient to relax and breath while maintaining pressure
MET for forward sacral tortions
ex. R on R
- stand on right side of patient (same as oblique axis)
- patient in Sim’s position with axis down
place hand to monitor lumbo-sacral junction
flex patients hips and knees until motion felt
- instruct patient to lower legs off table and push ankles toward floor
instruct them to lift ankles up to ceiling
MET for backward sacral torsions
ex: R on L
stand on axis of patient, place patient in lateral recumbent with axis down
- place hand to monitor lumbo-sacral junction
flex patients hips and knees, extend patients left leg (inducing sacral flexion) - apply posterior pressure on patients right shoulder (inducing right rotation)
- bring patients right leg off of table, apply doward pressure on knee and have patient push right knee up toward ceiling
