M1 Reading Guide

Question 1

What is the function of the curves in the spinal column (or, why is a curved spine better than a straight spine)?

Answer 1

• contributes to ideal spinal posture in standing

- reduces compressive load

Question 2

What do anterior concavities provide?

Answer 2

space for organs in the thoracic and pelvic cavities

Question 3

What is the primary WB component of the spinal column?

Answer 3

intervertebral discs

Question 4

Lumbar vertebral bodies function

Answer 4

• load bearing

- not designed to absorb 100% of the weight

Question 5

Curves of the spine help minimize _______

Answer 5

compressive load

Question 6

In addition to lumbar vertebral bodies and discs, what else help absorb a small amount of load?

Answer 6

facet joints

Question 7

What type of joints are facets?

Answer 7

synovial

Question 8

What is true of all synovial joints?

Answer 8

• mobile

- surrounded by pliable capsule

Question 9

SI joint starts out as this type of joint

Answer 9

synovial during childhood

Question 10

What type of joint does the SI become?

Answer 10

• modified diarthroidal synovial joint between puberty and adulthood
• » modified synarthroidal joint in adulthood

Question 11

Where do synovial joints get nutrition?

Answer 11

synovial fluid

Question 12

Are synovial joints sources of pain? Why or why not?

Answer 12

YES - highly innervated

Question 13

In what way does the facet joint capsule act as a ligament?

Answer 13

• limits motion at the interbody joint

- » supports and protects interbody joint and disc

Question 14

How are spinal motions distributed L1-L4?

Answer 14

• mostly vertical
• mostly sagittal plane
• allows a lot of flexion/extension
• doesn’t allow much rotation

Question 15

This serves to guide and limit motion in the lumbar spine

Answer 15

orientation of facet joints (?)

Question 16

Position of facet joints L5-S1

Answer 16

Change from vertical to a more oblique position between frontal and sagittal plane

Question 17

What function does a more oblique position of facets at L5/S1 serve?

Answer 17

resist anterior shear created by sacral angle of inclination

Question 18

What do shear and facet compression increase with?

Answer 18

• increased lordosis and/or

- increased angle of inclination

Question 19

What does the increased obliquity of the L5/S1 facets limit? (movements)

Answer 19

• lateral flexion

- rotation

Question 20

Gravity imposes a much higher degree of _______ force at L5-S1 than the rest of the lumbar spine

Answer 20

shear force

Question 21

What is the angle of inclination?

Answer 21

angle that the sacrum is tipped forward

Question 22

What is the shear force that goes through the L5-S1 joint? (%)

Answer 22

50%

If a person has 90# force directed through the spine, 45# is directed through this junction