Biomechanics of the Pelvis and Sacrum Flashcards Preview

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Flashcards in Biomechanics of the Pelvis and Sacrum Deck (25)
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1
Q

3-joint complex, with much the same function as the typical vertebral functional unit.

A

Pelvic joints: 2 SI joints + Pubic symphysis

2
Q

What is the least understood and most controversial function of any area in the musculoskeletal system?

A

Pelvic joints: 2 SI joints + Pubic symphysis

3
Q

Provide support for the trunk, guide movement, and help to absorb the compressive forces associated with locomotion and weight-bearing.

A

SI joint

4
Q

What is unique about the shape and configuration of the SI joints?

A

surface contours develop into interlocking elevations and depressions producing a KEYSTONE EFFECT of the sacrum, effectively distributing axial compressive forces through the pelvic mechanism.

5
Q

How are forces of the lower extremity distributed to the pelvic joints?

A

head upward toward the spine and anteriorly toward the pubic symphysis, and downward forces of gravity on the spine split to both sides

6
Q

The sacrum is __________ in shape and serves as a keystone in the arch b/w the two columns formed by the LE.

A

triangular

7
Q

Describe the SI joints at birth.

A

underdeveloped, smooth, and flat

8
Q

Describe the SI joints after ambulation.

A

begin to take on their adult characteristics

9
Q

Describe the SI joints in teen years.

A

joint surfaces begin to roughen and develop their characteristic grooves and ridges

10
Q

Describe the SI joints in later years.

A

high % of (male) patients will have interarticular adhesions across the SI joints and will have lost SI joint motion

11
Q

What are the 2 most common pelvic types?

A

Gynecoid and Android

12
Q
Describe the : 
Inlet-
Sacrosiciatic Notch -
Sacrum-
Subpbic Arch -

of a Gynecoid pelvis

A

inlet: round
Scrosciati N: Average size
Sacrum: Avg
Subpubic Arch: inclination well curved

13
Q
Describe the : 
Inlet-
Sacrosiciatic Notch -
Sacrum-
Subpbic Arch -

of an Android pelvis

A

inlet: triangular
Scrosciati N: Narrow
Sacrum: Forward
Subpubic Arch: inclination straight

14
Q

What are the ligaments of stability in the pelvis?

A
  1. Posterior Sacroiliac lig
  2. Sacrotuberous big
  3. Anterior sacroiliac lig
  4. Sacrospinous lig
15
Q

The SI joint os most active during what?

A

locomotion

16
Q

Describe the SI joint motion during locomotion.

A

The SI joints flex/extend in unison with the corresponding hip joint. Movements of flex/exten in one point are mirrored by the opposite movement at the other joint

17
Q

As the left innominate moves PI (post, infer), how does the left sacral base move?

A

AI (ant, infer) (nutation)

18
Q

As the right innominate moves AS (ant, sup), who does the right sacral base move?

A

PS (post, sup) (counternutation)

19
Q

The proposed axes of motion in the SI articulation allow a “_________” movement.

A

gyroscopic

20
Q

What muscles cross the SI joint?

A

None, silly! It provides stability, not mobility.

21
Q

What are the possible Pelvic sublations?

A
Ant
Superior 
Post 
Inferior 
External 
Internal
22
Q

What are the possible Sacral subluxations?

A

Apex (SAL, SAR)
Base Posterior (BP
(Apex posterior?)
Left/Right Posteriority (P-L, P-R)

23
Q

Sacral øz rotation: Apex Left

A

(+)øz

24
Q

Sacral øz rotation: Apex Right

A

(-)øz

25
Q

Sacral øx Rotation

A

AKA: Flexion malposition (nutation)
AKA: Extension malposition (counternutation)
* can also have neutral