Motion Segments Flashcards

1
Q

What is a motion segment?

A

The functional unit of the vertebral column since it allows movement

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2
Q

What does a vertebral motion segment consist of?

A

Two adjacent vertebrae

Soft tissues between them

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3
Q

What is the reference for definition of motion Segments?

A

Hall, 2014

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4
Q

What is the function of the vertebral bodies in the motion segment?

A

Allow body to support its weight
Stable attachment for IVDs, ligaments and muscles
(Duran et al., 2017)

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5
Q

What movements of the vertebral column do the annulus fibres of the IVDs resist? (Reference?)

A

Flexion
Extension
Torsion
(McNah and McCulloch, 1990)

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6
Q

What percentage of the nucleus pulposus is water?

A

90%

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7
Q

What are the other components of the nucleus pulposus apart from water? (Reference?)

A

Proteoglycans
Collagen
Glycosaminoglycans
(Palastanga et al., 2012)

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8
Q

What are the five steps involved in the development of the IV discs?

A
  1. Paraxial somites gather around notochord
  2. Pericordial condensation of sclerotome
  3. Metameric patterning of disc and vertebral bodies
  4. Involution of notochord
  5. Establishment of annulus fibrosus lamellar structure
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9
Q

How does the notochord form? (Reference?)

A

Epiblast cells invaginating at Hensen’s node and filling the mesoblastic space
(Colombier et al., 2014)

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10
Q

What does the nucleus pulposus derive from? (Reference?)

A

Notochord

Martinez et al., 2017

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11
Q

What does the annulus fibrosus derive from? (Reference?)

A

Sclerotome

Colombier et al., 2014

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12
Q

When does the notochord tend to be completely degraded and where can it remain up to 10 years of age? (Reference?)

A

Usually gone by 4-5 years of age
Can remain in IV disc up to 10 years
(Ashley et al., 2016)

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13
Q

What applies tension to IV discs?

A

Ligaments

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14
Q

What applies external loads to the IV discs?

A

Things we carry

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15
Q

Body weight and its compression on the vertebral column and IV discs is a risk factor for what?
(Reference?)

A

Lower back pain

Shiraz et al., 2015

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16
Q

What does a study by Yar (2008) show between body weight and IV discs?

A

Spinal shrinkage is associated with obesity

17
Q

What is torque?

A

The force that tends to cause rotation

18
Q

What is the equation for torque?

A

Torque (Nm) = Force (N) x Distance (m)
Force is the contraction of the muscles
Distance is the perpendicular lengths

19
Q

Why are annulus fibres always under stress? (Reference?)

A

Weight of IV disc

Palastanga

20
Q

How does the nucleus pulposus resist compression? (Reference?)

A

High fluid content

Hall, 2014

21
Q

What effect does the nucleus pulposus have on movement of the vertebral column? (Reference?)

A

Allows vertebrae to move efficiently and smoothly in all planes
(McNab and McCulloch, 1990)

22
Q

What did Duran et al., (2017) show in regards to IV disc degeneration?

A

Association between disc degeneration and morphology of vertebral body endplates:

  • Increased endplate sagittal concave angle in herniated disc
  • Decreased endplate sagittal concave depth in herniated disc
23
Q

What did Colombier et al., (2014) show in regards to IV disc degeneration?

A

There is a singular nucleus pulposus phenotype associated with it

24
Q

What is IV disc prolapse?

A

Nucleus pulposus pushes against a weakened area of annulus fibres

25
Q

How can annulus fibres weaken?

A
Over time:
- Age
- Working with heavily vibrating machinery
Suddenly:
- Lifting heavy object with poor form
26
Q

What vertebral region is IV disc prolapse most common?

A

Lumbar

27
Q

What are the symptoms of IV disc prolapse?

A
Back/Neck pain/tingling/numbness
Issues with back movements
Cord compression if:
- Large prolapse
- Posterior prolapse
28
Q

What are the conservative options for treatment of IV disc prolapse?

A

Analgesia
Physiotherapy
Muscle relaxants
Steroid injections

29
Q

What are the surgical managements of IV disc prolapse?

A

Laminotomy to relieve pressure on nerve roots
Discectomy
Self-closing U-clips for Duran repair

30
Q

What is IV disc sequestration? (Reference?)

A

Nucleus pulposus separates from IV disc by seeping out through annulus fibres
(Harder et al., 2015)

31
Q

What is the most common cause of IV disc sequestration?

A

Weakness due to ageing

32
Q

What are the symptoms of IV disc sequestration?

A

More severe:

  • Back pain
  • Numbness and tingling
  • Muscle weakness