2. Biomechanics Of The Pelvis

Question 1

The static function of the pelvis is to support the trunk and resist _______.

Answer 1

Downward shear

Question 2

inferior displacement of the sacrum is resisted by ______.

Answer 2

wedge shape of the sacrum

Question 3

posterior displacement of the sacrum is resisted by ______.

Answer 3

Posterior SI ligaments (interosseous and dorsal ligaments)

Question 4

Anterior displacement of the sacrum is resisted by ______.

Answer 4

Anterior sacroiliac joints and the pubic symphysis

Question 5

The anatomy of the SI joints promoting stability is referred to as ______ closure.

Answer 5

Form

Question 6

Tension in muscles, ligaments and thoracolumbar fascia aiding in stabilizing the SI joints is referred to as ____ closure.

Answer 6

Force

Question 7

What anatomy of the SI joint promotes form closure?

Answer 7

• wedge shaped sacrum
• interlocking groove and ridge
• S shaped joint surface

Question 8

Tension in muscles, ligaments and thoracolumbar fascia creates _____ to _____ pressure which compresses the SI joint

Answer 8

Lateral to medial

Question 9

How does the pelvis act as a shock absorber?

Answer 9

It slides and pivots to absorb and adapt to forces generated between trunk and lower extremity during locomotion

Question 10

What are the kinematic of the SI joint?

Answer 10

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

Question 11

What is the range of motion of the SI joint?

Answer 11

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

Question 12

What is the predominant plane of motion in the SI joint?

Answer 12

Around the x-axis in the smile sagittal plane

Question 13

Where is the axis of rotation of the SI joint?

Answer 13

It is speculative but most commonly placed posterior to the joint around the iliac tuberosity

Question 14

Is motion of the SI joint coupled?

Answer 14

Yes

Question 15

Why is motion of the SI joint not uniform between individuals?

Answer 15

Developmental changes in surface architecture

Question 16

When is movement of the SI joint the greatest?

Answer 16

During locomotion

Question 17

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.

Answer 17

ipsilateral anterior inferior (SI flexion, sacral nutation)

Question 18

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.

Answer 18

ipsilateral posterior superior (SI extension, sacral counternutation)

Question 19

The most influential model of locomotion for the pelvis states that motions lead to a complex movement of _______ of the sacrum between the ilium.

Answer 19

circumduction (gyroscopic)

Question 20

The movement of the sacrum during locomotion can also be described as a _____ and _____ figure 8.

Answer 20

Oblique and horizontal

Question 21

What palpation test is used to evaluate SI motions that occur during locomotion?

Answer 21

Gillet’s test

Question 22

Anterior inferior movement of the sacral base (nutation) creates lumbosacral ______.

Answer 22

Extension

Question 23

Anterior inferior movement of the sacral base (nutation)relative to the ilium creates _____

Answer 23

SI flexion

Question 24

Posterior superior movement of the sacral base (counter nutation) creates lumbosacral _____.

Answer 24

Flexion

Question 25

Posterior superior movement of the sacral base (counter nutation) relative to the ilium creates ______

Answer 25

SI extension

Question 26

The hip hike test is demonstration what part of Pubic Symphysis Kinematics?

Answer 26

Gliding (shear) compression and separation (translation along the y-axis)

Question 27

What is the kinematics of the pubic symphysis with flexion/extension of the SI joints?

Answer 27

Rotation around the x-axis/sagittal plane