Sacro-iliac Joint Anatomy and Biomechanics

Question 1

ANTERIOR and POSTERIOR LIGAMENTS

Answer 1

EXTENSIVE ANTERIOR AND POSTERIOR LIGAMENTS
Anterior ligament consist of numerous thin bands that connect the anterior surface of the lateral part of the sacrum to the margin of the auricular surface of the ilium and to the preauricular sulcus.
POSTERIOR LIGAMENTS situated in the deep depression between the sacrum and ilium behind. Strond and forms the chief bond of union between the bones
IT HELPS FIGHT THE FORCES OF GRAVITY–SACROTUBEROUS LIGAMENT–GRAVITY PULLS US INTO NUTATION

Question 2

INTEROSSEOUS LIGAMENT

Answer 2

Deep to the posterior ligament, consist of a series of short, strong fibers connecting the tuberosities of the sacrum and ilium. Major function is to keep the sacrum and ilium together and prevent abduction or distraction of the sacroiliac joint. This is performed by the nearly horizontal direction of the fibers running perpendicular from the sacrum to the ilium.

Question 3

SCAROILIAC JOINT

Answer 3

HAVE A SMALL AMOUNT OF IMPORTATNT MOVEMENT

AND STRUCTURES THAT CAN CREATE PAIN

Question 4

Sacroiliac JOINT

Answer 4

1-SIGNIFICANT SHEAR FORCES IN STANDING
2-KEYSTONE EFFECT GIVES STABILITY (FROM CLOSURE)
3-MUSCULAR ACTIVITY (FORCE CLOSURE)
4-SACRAL NUTATION/INOMINATE POSTERIOR ROTATION CREATES A SELF- LOCKING MECHANISM

Question 5

SACRAL NUTATION IS THE

Answer 5

LOCKING POSITION OF THE si JOINT

Question 6

The sacroilian joint is an Irregular joint

Answer 6

1. Irregular joint surfaces

2. deformable to allow for motion

Question 7

Pubic Symphsis

Answer 7

closed bony ring (same type of joint as an intervertebral joint) Keystone of rotation of pelvis as well as axis of rotation of SI joint

Question 8

Pelvic Position

Answer 8

ASIS and Pubis Symphysis will remain in the same plane
Posterior tilt=Pubic symphysis protrudes beyond the ASIS
Anterior tilt=ASIS protrudes beyond pubic symphysis

Question 9

In a neutral position the ASIS and the Pubic Symphysis

Answer 9

are in line with each other vertically

Question 10

Mobility is necessary for shock absorption

Answer 10

Very small ROM <4

-1.6 mm of translation

Question 11

Hip Motion Bilateral Hip Flexion

Answer 11

Posterior Pelvic tilt

Question 12

Bilateral Hip Extension

Answer 12

Anterior Pelvic Tilt

Question 13

Unilateral Hip Flexion

Answer 13

Posterior tilt and outward rotation

Question 14

Unilateral Hip Extension

Answer 14

Anterior tilt and inward rotation

Question 15

Flexion Trunk Motion

Answer 15

Anterior Rotation Innominate motion

Question 16

Extension Trunk motion

Answer 16

Slight posterior rotation

Question 17

Sidebending Left

Answer 17

Left anterior rotation and right posterior rotation

Question 18

Rotation Left

Answer 18

Left posterior Rotation

Right AnteriorRotation

Question 19

Anterior Inominate rotation

Answer 19

functionally lengthens LE

Question 20

Posterior innominate rotation

Answer 20

Functionally shortens LE

Question 21

Can see Inominate rotations as

Answer 21

compensation or mimic leg length discrepancy

Question 22

Limb Length Descrepancy

Answer 22

Posterior Rotation Inominately to allow for shortening of the longer leg

Question 23

Muscle Imbalance

Answer 23

Anterior Inominate Rotation-functionally lengthens LE
Posterior Inomminate Rotation-functionally shortens LE
Can see inominate rotations as compensation or mimic leg length discrepancy