SACRUM Flashcards
Standing: what influences pelvis?
pelvis influenced by both structures and functional asymmetry of LE’s
Seated: what influences pelvis?
Innominate stabilized by weight on ischial tuberosity, influenced by position of spine and tension in trunk
Prone: what influences pelvis?
pelvis supported by pubic symphysis and ASIS, sacrum responds to trunk
Supine: what influences pelvis?
stabilized by WB on table, innominate respond to tension from below
Superior pub
R one that is higher = R superior pub
L one that is higher = L superior pub
we expect 2 superior pubic ramus to be equal in supine and in standing position
inferior pub
L one that is lower = L inferior pub
R one that is lower = R inferior pub
we expect 2 superior pubic ramus to be equal in supine and in standing position
Anterior innominate
Right:
Anterior view
ASIS/ASIS
PSIS/PSIS
Lateral view on the right
ASIS/PSIS
Lateral view on the left
ASIS/PSIS
= anterior rotation: if the right side rotates forward, there is an anterior rotation of the right innominate bone
Viewing from anterior view the right ASIS is inferior to ASIS on the left
PSIS on the right is supserior to left PSIS
Lateral from right: ASIS is inferior to PSIS
Lateral from left:
ASIS and PSIS are equal
If it were anterior pelvic tilt then the PSIS would be higher than ASIS from both lateral views: we need to look from both sides to see if it is a unilateral dysfunction
Posterior innominate:
R
Anterior view:
Posterior:
Lateral right:
Lateral Left:
Anterior view: Right ASIS superior
Posterior: right PSIS is lower
Lateral right: ASIS higher than PSIS
Lateral Left: ASIS and PSIS are even
Opposite of an anterior innominate
This can occur on either side (can get an anterior or posterior innominate on R or on L)
Where should the ASIS and PSIS be aligned?
2 ASIS should be equidistant from umbilicus
2 PSIS should be equidistant from center point of sacrum, SP of sacrum
Inflare
anterior view
posterior view
lateral view
medial rotation around the Y axis
Anterior View: we look at ASIS from anterior view on the side of the rotation is closer to the umbilicus than the ASIS of contralateral side
Posterior View: If turn the person around, PSIS is lateral to center of sacrum compared to the PSIS on the contralateral side.
Lateral view wont show anything
Outlfare
anterior view
posterior view
Lateral rotation around the y axis
Anterior view – ASIS is laterally displaced from umbilicus compared to other side
Posterior view – PSIS medially displaced from sacrum
Upslip
anterior view
posterior view
lateral view
Crest heights (WB vs NWB)
Ischial tuberosity
“superior ilial sheer” or “superior innominate sheer”
: entire right hemipelvis becomes superiorly displaced
Anterior view – ASIS superior
Lateral view – unless there is a rotation coupled with it – it wont look different because it’s level
Posterior view – PSIS is superior
Crest heights in NWB: the iliac crest will be high on the side of the superior displacement
(Not in WB because if your leg lengths are the same, and the leg is planted on the ground, the pelvis will level out and your spine will take up the slack (back accommodates for it)
Ischial Tuberosity: When you look at this, and examine the patient in prone, their ischial tuberosity will also be superiorly displaced because entire hemipelvis will be superiorly displaced
Downslip
- Anterior view
- Posterior view
- Iliac crests
- IT’s
Inferior ilial sheer or inferior innominate sheer
- Anterior view – ASIS inferior
- Posterior view – PSIS inferior
- Iliac crests – iliac crest inferior
- Look at relationships of IT’s – R would be inferior
Where is middle transverse axis located?
L3
Where is Right oblique axis?
diagonal axis: Right promontory and travels obliquely across sacrum and comes out on L ILA
Where is Left oblique axis?
diagonal axis: Left promontory (sacral base) and travels to right ILA
Inhalation: how it affects sacrum?
sacrum is going to come backwards
Exhalation: how it affects sacrum?
sacrum is going to come forward
which axis at which we find motion related to sacrum that is connected to respiration?
Superior Transverse Axis:
inhale: sacrum goes posterior
exhale: sacrum comes anterior
which axis nutation and counternutation?
middle transverse axis
Nutation
- what motion/axis
- what widens/narrows
1) Anterior rotation around middle transverse axis, S2,3, where promontory moves anteriorly and inferiorly
2) Pelvic brim is decreased and pelvis outlet is increased
- –Movement anteriorly around Middle transverse axis: promontory/sacral base moves anteriorly, apex (cornu) moves posteriorly
Counternutation:
1) Promontory moves superiorly and posteriorly
2) Pelvic brim is increased and pelvic outlet is decreased
- 1. Sacral base – posterior superior/Cornu – anterior inferior
Are Nutation and Counternutation are normal movements?
happen when you breathe
- Bring both legs up together to chest– counternutation
- Extension – nutation
Normal physiological movements
Right on Right
what is it
is it bad?
right rotation around a right oblique axis
Considered to be a normal physiological movement–ie during gait: HS = anterior torsion
**With any movement in the innominate bone or the sacrum the problem is when get stuck in the position whether it is a normal or abnormal movement. So even if the right on right moves right on right and return to neutral is no problem, but if get stuck in right on right and have trouble getting back to neutral, it is still a problem. It is more painful and problem if it is an abnormal movement and it will be more painful and a more significant finding.
Left on Right
left on right: left rotation around the right oblique axis
This is a posterior torsion and is a non physiological movement, it does not take place normally -due to trauma
Left on Left
Rotate anteriorly around the left oblique axis: rotate towards the left
Left rotation around the left oblique axis which is referred to as an ANTERIOR TORSION and it is a normal physiological movement
Right on Left
Right rotation around left oblique axis is a POSTERIOR TORSION, and it is a non physiological movement
Sacral Extension
where does sacral base go? ILA?
unilateral superior sacral shear
- Hemisacrum slides along side of facet in superior direction
- Sacral promontory moves posteriorly and superiorly
- ILA moves superiorly
Sacral Flexion
where does sacral base go? ILA?
Inferior Unilateral Sacral Sheer
Sacrum sheers in an inferior direction, it slides along the facet joint
Sacral base goes forward and inferiorly
ILA: moves inferiorly
GAIT: Iliosacral Movement:
each innominate rotates anteriorly and posteriorly during the walking cycle
GAIT: Sacral Movement
The axis of rotation originates on the side of the weight bearing leg
L on L, return to neutral, then R on R, then return to neutral
At midstance of gait cycle the axis of rotation of sacrum is on the side of the weight bearing leg and it is always an anterior torsion.
i. The axis of rotation originates on the side of the weight bearing leg
when the sacrum rotates to the right, simultaneously what sidebending does it do?
when the sacrum rotates to the right, simultaneously it does left side bending
When sacrum rotates it also does contralateral side bending
how lumbar spine moves in relation to sacrum?
When sacrum rotates, the lumbar spine rotates to the opposite side/ when sacrum sidebends, lumbar spine sidebends to the opposite side
Baer’s Point
dutton
1/3 of the way down on the diagonal that goes between ASIS and the pubic symphysis
Gives more a superior part of the SI joint
Baer’s Point
Minel
2 inches from umbilicus (more medially) between umbilicus to ASIS
Gives you more inferior part of joint
sacral sulcus
Space between sacral base and PSIS:
tells us about relationship between innominate and sacrum
Piriformis muscle
palpation
Attaches from the anterior inferolateral aspect of the sacrum to greater trochanter
Trace along length to palpate
Piriformis is over the sciatic nerve (15% of population, sciatic nerve goes through but most of the time is goes under)
You will only feel it if it is in spasm