2. Biomechanics Of The Pelvis Flashcards
The static function of the pelvis is to support the trunk and resist _______.
Downward shear
inferior displacement of the sacrum is resisted by ______.
wedge shape of the sacrum
posterior displacement of the sacrum is resisted by ______.
Posterior SI ligaments (interosseous and dorsal ligaments)
Anterior displacement of the sacrum is resisted by ______.
Anterior sacroiliac joints and the pubic symphysis
The anatomy of the SI joints promoting stability is referred to as ______ closure.
Form
Tension in muscles, ligaments and thoracolumbar fascia aiding in stabilizing the SI joints is referred to as ____ closure.
Force
What anatomy of the SI joint promotes form closure?
- wedge shaped sacrum
- interlocking groove and ridge
- S shaped joint surface
Tension in muscles, ligaments and thoracolumbar fascia creates _____ to _____ pressure which compresses the SI joint
Lateral to medial
How does the pelvis act as a shock absorber?
It slides and pivots to absorb and adapt to forces generated between trunk and lower extremity during locomotion
What are the kinematic of the SI joint?
Movement present but precise pattern remains unclear
difficult to establish one consistent model of SI motion due to limited research, individual variation and relatively small amount of total motion
What is the range of motion of the SI joint?
Though the exact amount of movement is debated, most agree that it is relatively small. (0.54 to 8 degrees has been shown in various studies)
- motion decreases with age
- more motion in females
What is the predominant plane of motion in the SI joint?
Around the x-axis in the smile sagittal plane
Where is the axis of rotation of the SI joint?
It is speculative but most commonly placed posterior to the joint around the iliac tuberosity
Is motion of the SI joint coupled?
Yes
Why is motion of the SI joint not uniform between individuals?
Developmental changes in surface architecture
When is movement of the SI joint the greatest?
During locomotion
The most influential model of locomotion for the pelvis states that flexion of the hip and ilium (posterior inferior movement of the PSIS) is
accompanied by ______ movement of the sacral base.
ipsilateral anterior inferior (SI flexion, sacral nutation)
The most influential model of locomotion for the pelvis states that extension of the hip and ilium (anterior superior movement of the PSIS) is
accompanied by ______ movement of the sacral base.
ipsilateral posterior superior (SI extension, sacral counternutation)
The most influential model of locomotion for the pelvis states that motions lead to a complex movement of _______ of the sacrum between the ilium.
circumduction (gyroscopic)
The movement of the sacrum during locomotion can also be described as a _____ and _____ figure 8.
Oblique and horizontal
What palpation test is used to evaluate SI motions that occur during locomotion?
Gillet’s test
Anterior inferior movement of the sacral base (nutation) creates lumbosacral ______.
Extension
Anterior inferior movement of the sacral base (nutation)relative to the ilium creates _____
SI flexion
Posterior superior movement of the sacral base (counter nutation) creates lumbosacral _____.
Flexion
Posterior superior movement of the sacral base (counter nutation) relative to the ilium creates ______
SI extension
The hip hike test is demonstration what part of Pubic Symphysis Kinematics?
Gliding (shear) compression and separation (translation along the y-axis)
What is the kinematics of the pubic symphysis with flexion/extension of the SI joints?
Rotation around the x-axis/sagittal plane
