Structure of the Lx spine and SIJ

Question 1

What are the functions of the IV disc?

Answer 1

• Weight transmission
• Shock absorption
• Increases ROM

Question 2

What is the structure of pedicles in the Lx spine?

Answer 2

Connect the body to the TPs

Short and strong

Question 3

What is the structure of lamina in the Lx spine?

Answer 3

Connect the TPs to the SP

Narrow

Question 4

What is the mammilary body?

Answer 4

Rounded edge on the posterosuperior joint surface - for bony attachment

Question 5

What is the shape of the articular surfaces in the Lx spine?

Answer 5

superior facets - concave - run posteromedially

inferior facets - convex - run anterolaterally

Nearly vertical facets = reduce rotation

Question 6

What type of joints are in the Lx spine?

Answer 6

Intervertebral symphysis

With synovial plane joints as the articular facets

Question 7

What type of joint is the L5/S1 joint?

Answer 7

Lumbosacral joint - secondary cartilaginous joint and 2x synovial plane joints

Question 8

How does the L5/S1 joint differ from the rest of the lumbar spine?

Answer 8

It is strengthened by several ligaments which make it less mobile = higher point of injury

Disc is particularly thick and wedge shaped = prone to slippage

L5 has larger vertebral body and stronger TPs due to weightbaring

Question 9

What are the additional ligaments of the lumbosacral joint?

Answer 9

Illiolumbar ligament

Lateral lumbosacral ligament

Question 10

What are the attachments of the illiolumbar ligaments?

Answer 10

O: transverse processes of L4 and L5

I: anterior lip of iliac crest

Question 11

What is the function of the iliolumbar ligament?

Answer 11

Prevents lateral movement of L4 and L5

Stabilises the lumbar spine during flexion, extension and lateral flexion

Question 12

What are the attachments of the lateral lumbosacral ligament?

Answer 12

O: transverse processes of L5

I: Ala of sacrum

Question 13

What is the function of the lateral lumbosacral ligaments?

Answer 13

Improves stability of the lumbosacral joint

Limits lateral movement of L5

Question 14

What is the classification of the sacroiliac joint?

Answer 14

Synovial modified plane joint

Anteriorly = synovial

Posteriorly = fibrous

Question 15

Describe the articular surfaces of the SIJ?

Answer 15

L shaped articular surfaces – broader above and narrower below – showing reciprocal irregularities. Bones fit into each other restricting movement – increases stability and strength.

Question 16

What are the ligaments of the SIJ?

Answer 16

• Anterior sacroiliac ligament
• Posterior sacroiliac ligament
• Interosseous sacroiliac ligament

2x accessory ligaments:

• sacrotuberous ligament
• sacrospinous ligament

Question 17

What are the attachments fo the anterior sacroiliac ligament?

Answer 17

O: ala and pelvic surface of sacrum

I: Pelvic surface of ileum

Question 18

What is the function of the anterior sacroiliac Ligament?

Answer 18

Prevents anterior movement of sacrum on ileum

Question 19

What are the attachments of the posterior sacroiliac ligaments?

Answer 19

O: PSIS

I: Short band = 1st and 2nd transverse tubercles of sacrum

Long band = 3rd and 4th transverse tubercles of sacrum

Question 20

What is the function of the long band posterior sacroiliac ligament?

Answer 20

Resists downwards movement fo sacrum

Question 21

What is the function of the short band posterior sacroiliac ligament?

Answer 21

resists forwards movement of the sacrum

Question 22

What are the attachments of the interosseous sacroiliac ligament?

Answer 22

Fills the cleft behind and above the auricular surfaces = connecting the ileum and sacrum

Question 23

What is the function of the interosseous sacroiliac ligament?

Answer 23

Keeps the sacrum and ilium tightly secured

Question 24

What are the attachments of the sacrotuberous ligament?

Answer 24

O: lower transverse tubercles and inferior sacrum/coccyx

I: ischial tuberosity

Question 25

What is the function of the sacrotuberous ligament?

Answer 25

prevents forwards tilt of sacrum

Question 26

What are the attachments of the sacrospinous ligament?

Answer 26

O: lower sacrum and upper coccyx

I: ischial spine

Question 27

What is the function fo the sacrospinous ligament?

Answer 27

Prevents forwards tilt of the sacrum