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South College MSK 1 > Week 1- Lumbar Biomechanics > Flashcards

Week 1- Lumbar Biomechanics Flashcards

1
Q

What subsystems are under consideration for lumbar biomechanics?

A
  • Passive –> Spinal column
  • Active –> Spinal muscles
  • Control –> Neural
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2
Q

Describe the load distribution present in the spinal column and IV discs

A
  • 80% through vertebrae and interbody joint

- 20% posterior elements (i.e. the facet joints)

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3
Q

What factors may impact the load distribution?

A
  • Position
  • Age
  • Trauma
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4
Q

Parts of the intervertebral disc

A
  • Annulus fibrosis

- Nucleus pulposus

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5
Q

Purpose of the annulus fibrosis

A
  • Contain nucleus pulposus

- Provide strength, flexibility, and protection from external forces

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6
Q

Describe the fiber orientation of the annulus fibrosis

A

Concentric rings, alternating in orientation (65 degrees)

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7
Q

What is the water content of the nucleus pulposus?

A

70-90% in younger individuals

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8
Q

Purpose of the nucleus pulposus

A

Shock absorption

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9
Q

What happens as a result of disc dehydration?

A

Increase load to facet joints

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10
Q

Describe the process of dehydration and rehydration of the nucleus pulposus throughout the day

A
  • Lose ~25% during the day

- Rehydrate at night

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11
Q

What process may lead to bulging in the disc?

A

Depressurization from age or trauma causes the disc to lose uniform cushioning

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12
Q

What positions maximize intradiscal pressure?

A

Leaning over while holding a weighted object

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13
Q

What positions minimize intradiscal pressure?

A

Laying down or sitting with the back supported

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14
Q

What kind of joint is the zygapophyseal (facet) joint?

A

Synovial plane joint

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15
Q

What movements do the facet joints allow in the lumbar spine?

A
  • Mostly flexion, but also restrains excessive flexion to protect the IVD
  • Limits rotation
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16
Q

What do the facet joints do to block anterior translation of the vertebrae?

A
  • The vertebrae are tilted such that they experience an anterior shear vector
  • Facet joints work with the ALL to stabilize these joints and protect the spinal cord
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17
Q

What is tropism?

A

Notable variation in facet plane

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18
Q

What role does tropism play in lumbar vertebral stability?

A

May impair ability to resist forward displacement/rotation

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19
Q

What role might fat plugs play in LBP?

A
  • AKA fat pads and meniscoids

- Innervated, so they may be a source of symptoms

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20
Q

What are the components of a motion segment in the spine?

A
  • Superior vertebrae
  • Intervertebral disc/interbody joint
  • Inferior vertebrae
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21
Q

How does a facet joint influence movement in the spine?

A

The orientation of the joint guides movement

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22
Q

What is the role of the intervertebral disc in the motion segment?

A

Absorb/distribute load

23
Q

What is the convention for naming movement in the vertebral motion segment?

A
  • Superior vertebrae on inferior

- Direction of anterior surface of vertebral body

24
Q

What motions are found in Fryette’s Laws?

A
  • Type 1 (neutral)
  • Type 2 (non-neutral)
  • Type 3
25
Q

Type 1 Mechanics

A
  • Coupled motions in opposite directions

- LF to one side is accompanied by rotation to opposite

26
Q

Type 2 Mechanics

A
  • Coupled motion in same direction

- LF to one side is accompanied by rotation to same side

27
Q

Type 3 Mechanics

A

Motion in 1 plane reduces available ROM in all remaining planes

28
Q

What happens to the superior vertebra in a lumbar motion segment during lumbar flexion?

A
  • Anterior rotation

- Translates anteriorly

29
Q

What happens anteriorly in a lumbar motion segment during lumbar flexion?

A
  • Compresses anterior disc (annulus)

- Anterior longitudinal ligament laxity

30
Q

What happens posteriorly in a lumbar motion segment during lumbar flexion?

A
  • Inf. articular process of superior vertebra moves superiorly on sup. articular process of inferior vertebra
  • Facet joints “open”
  • Separation of spinous processes, tightening posterior ligaments, facet capsules
31
Q

How much movement is allowed in lumbar flexion?

A

45-55 degrees

32
Q

What happens to the superior vertebra in a lumbar motion segment during lumbar extension?

A
  • Posterior rotation

- Translates posteriorly

33
Q

What happens anteriorly in a lumbar motion segment during lumbar extension?

A

Tension in anterior disc, ALL, and anterior musculature

34
Q

What happens posteriorly in a lumbar motion segment during lumbar extension?

A
  • Inf. articular process of superior vertebra moves inferior on sup. articular process of inferior vertebra
  • Facets “close”
  • Posterior ligaments and facet capsule lax
35
Q

How much movement is allowed in lumbar extension?

A

15-25 degrees

36
Q

What is the lumbopelvic rhythm?

A

Coordinated movements b/t lumbar spine and pelvis during flexion/extension

37
Q

What is the lumbopelvic rhythm during flexion?

A

Lumbar flexion followed by anterior pelvic tilt

38
Q

What is the lumbopelvic rhythm during extension?

A

Posterior pelvic tilt followed by lumbar extension

39
Q

What happens superiorly during lumbar axial rotation?

A
  • Sup. vertebra rotates around vertical axis

- 5-7 degrees

40
Q

What limits lumbar axial rotation?

A

Sagittal plane alignment, facet joints, facet separation/approximation, and annulus tension

41
Q

What happens superiorly during lumbar lateral flexion?

A
  • Rotates around AP axis

- Translates laterally along horizontal axis

42
Q

What happens on the side of convexity during lateral flexion?

A
  • Contralateral side
  • Goes under tension
  • Inf. articular facet of superior vertebra translates superior to sup. articular facet of inferior vertebra
43
Q

What happens on the side of concavity during lateral flexion?

A
  • Ipsilateeral
  • Becomes lax
  • Inf. articular facet of superior vertebra translates inferior to sup. articular facet of inferior vertebra
44
Q

Normal ROM for lumbar lateral flexion

A

~20 degrees

45
Q

What categories of muscles are found in the lumbar region?

A
  • Intrinsic

- Extrinsic

46
Q

What is the function of the intrinsic muscles?

A

Precision control due to the high degree of muscle spindles

47
Q

What is the structure of the intrinsic muscles?

A

They are deep, short muscles

48
Q

List the intrinsic lumbar muscles

A
  • Semispinalis
  • Multifidus
  • Rotatores
  • Interspinalis
  • Intertransversasrius muscles
49
Q

What is the function of the extrinsic muscles?

A
  • Coarse control of stabilization

- Torque production

50
Q

What is the structure of the extrinsic muscles?

A
  • Superficial

- Span multiple segments

51
Q

List the extrinsic lumbar muscles

A
  • 4 abdominals
  • Erector spinae
  • QL
  • Psoas major
  • Hip muscles
52
Q

What is the role of the diaphragm and pelvic floor in the lumbar spine?

A

Maintain IAP for stability

53
Q

What is the role of the neural subsystem?

A
  • Receive input from passive and active subsystems

- Determine requirement for maintaining stability

54
Q

What may impair the effectiveness of the neural subsystem?

A
  • Injury

- Failure to regain control may lead to further injury

South College MSK 1 (15 decks)

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