M1 Reading Guide 4

Question 1

What are the two types of bone in a vertebra?

Answer 1

• compact (cortical)

- trabecular (spongy/cancellous)

Question 2

compact bone withstands

Answer 2

greater stress

Question 3

trabecular bone withstands

Answer 3

compression

Question 4

What happens to trabecular bone in response to stress?

Answer 4

hypertrophy

Question 5

What happens to trabecular bone in the absence of loading?

Answer 5

• becomes smaller and weaker

- osteoporosis

Question 6

In standing or forward trunk flexion of the lumbar spine, what does the pars interarticularis resist?

Answer 6

shearing forces

Question 7

In standing or forward trunk flexion of the lumbar spine, when is the pars interarticularis most likely to fail?

Answer 7

repetitive loading with:

• flexion
• extension

especially at end range

Question 8

Most common level of pars interarticularis failure

Answer 8

L5-S1

Question 9

Unilateral failure or lengthening of the pars interarticularis =

Answer 9

spondylolysis

Question 10

bilateral failure or lengthening of the pars interarticularis =

Answer 10

spondylolysthesis

Question 11

If the pars fails or lengthens bilaterally, what is likely to occur subsequently between the two adjacent segments?

Answer 11

anterior slippage of top vertebra over the vertebra below it

Question 12

What are the two main functions of the annulus fibrosis?

Answer 12

check for accuracy

• encase/physically entrap the liquid based central nucleus
• absorb shock and load, allow/restrict movement

Question 13

Outer peripheral rings of the annulus contain

Answer 13

blood vessels

Question 14

Inner layers of the annulus contain

Answer 14

less type I collagen and more water

Question 15

What is the consistency of the nucleus pulposus?

Answer 15

pulp-like gel

Question 16

Composition of nucleus pulposus during youth? 70-90% _____

Answer 16

water

Question 17

What thickens the nucleus pulposus with aging?

Answer 17

proteoglycans

Question 18

In addition to water, what is also part of the nucleus pulposus?

Answer 18

• Type II collagen fibers
• Elastin fibers
• other proteins
• chondrocytes
• fibrocytes

mucopolysaccharide matrix and loose array of collagen

Question 19

How does aging impact the NP?

Answer 19

diminishes ability to imbibe water

Question 20

What happens to the NP during hte day?

Answer 20

upright posture results in

• compressive forces
• NP loses water

Question 21

What happens at night to the NP?

Answer 21

NWB recumbency causes the NP to imbibe water and nutrients » » » disc height increases