Download Sacral and Innominate Anatomy and Mechanics

Sacral and Innominate
Anatomy and Mechanics
Michael Ladewski, DO
April 21, 2010
Objectives

Review Anatomy
Bones
 Landmarks
 Ligaments
 Articulations
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Review Mechanics of Sacral Motion
Questions and Hands-on Evaluation
Anatomy - Pelvis
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Pelvis:
Sacrum
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At the distal end of axial
spine
1 of the 3 separate bones
that form the pelvis
Innominate (Hip Bone)

2 each form pelvis with
Sacrum
Anatomy - Sacrum

Shaped like an inverted
triangle
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Base – superior aspect
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Sacral Promontory
Apex – inferior aspect
Anterior surface concave
Posterior surface convex
Anatomy - Sacrum

Inferior Lateral Angle
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Inferior portion of
Sacrum bilaterally
Sacral Sulcus

Palpable groove just
medial to PSIS
Anatomy - Innominate
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

1. Having no name.
2. Anonymous.
Each Hip Bone
composed of 3 bones
joined together at
acetabular notch
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Ischium
Ilium
Pubis
Anatomy - Ligaments

Spanning Sacrum and
Innominate
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Anterior Sacroiliac
Interosseous Sacroiliac
Posterior Sacroiliac
Sacrotuberous
Sacrospinous
Spanning Lumbar
Vertebrae/Sacrum/Ilium

Iliolumbar
Anatomy - Ligaments
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Iliolumbar
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Sacrospinous and
Sacrotuberous

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Integrate sacroiliac
mechanics with lumbar
spine
Restrain anterior
movement of sacrum
Sacroiliac

Restrain posterior, lateral,
axial rotation
Anatomy - Articulations

Pubis Symphysis


Fibrocartilaginous joint
Muscular forces acting on
each pubic ramus can
cause rotation upon each
other
Anatomy - Articulations
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Sacroiliac Joint
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L- or C-shaped
Shorter upper arm
Longer lower arm
Apex or junction of the
two arms points anteriorly
Mechanics of Sacral Motion
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4 Types of Sacral Motion
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1. Respiratory Motion

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Occurs about the superior
transverse axis
During inhalation sacral
base moves posterior
During exhalation sacral
base moves anterior
Mechanics of Sacral Motion

4 Types of Sacral Motion
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2. Inherent Motion



Occurs about the superior
transverse axis
During craniosacral flexion
sacral base moves posterior
During craniosacral
extension sacral base
moves anterior
Mechanics of Sacral Motion

4 Types of Sacral Motion

3. Postural Motion

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Occurs about the middle
transverse axis
As a person begins to bend
forward, sacral base moves
anterior
Mechanics of Sacral Motion

4 Types of Sacral Motion
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4. Dynamic Motion


Occurs about the inferior
transverse axis
As weight bearing shifts
from one side to the other
while walking, the sacrum
engages oblique axis
Hands-On Evaluation

Sacrum
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
Sacral Sulcus
ILA Bilaterally
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Innominate
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ASIS
PSIS
Iliac Crest