Muscles/Ligaments/Tendons tutorial Wk 6 Flashcards

1
Q

What factors many contribute to high “muscle tone” or higher muscle stiffness in an affected musculotendinous unit of a child with CP?

A

Increase on collagen content and sarcomere length –> increase passive tension

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2
Q

Describe spasticity and contracture using language that is appropriate for a patient of a child with CP

A
  • Spasticity is just when your muscle continue to contract without any control from the person this is due to an upper motor neuron lesion. This is due to a decreased inhibition of stretch reflexes
  • Contractures is when your muscles continuously contract without control and this causes your muscles, tendons and ligaments to become hardened and causes deformity and rigidity of your joints
  • Spasticity- neural
  • Contractures- non-neural
  • With CP = loss of function, greater contraction affects bones
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3
Q

What is the order of events that can lead to spasticity and contractures of the musculotendinous unit?

A

Muscles sense stimulus (fake) –> sends signal to troponin for tropomyosin to open the myosin heads –> actin attaches –> actin and myosin cross bridging

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4
Q

Which structures transmit forces passively?

A
  • Actin and myosin cross bridging generate force
  • Titin (anchors myosin to z line) and connective tissue (endomysium; perimysium; epimysium transmits force passively
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5
Q

Where do most injuries occur within the musculotendinous unit?

A

musculotendinous junction

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6
Q

Why is the musculotendinous junction the most prone location to injury?

A
  • Going from a elastic material to a more stiff material
  • A lot of force being transmitted
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7
Q

What is the pre-cursor of somites?

A

Mesoderm

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8
Q

What does the notocord do?

A

sends out stimulus to differentiate- neural tube

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9
Q

What structures develop from mesoderm?

A

dermatomes; myotomes; scleratomes –> skeletal muscles, skin, bone and connective tissue In series and bilateral paired- symmetry

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10
Q

Describe some of the changes that are likely with active loading (e.g. increased exercise) to: Tendon stiffness

A
  • increases tendon stiffness
  • isometric (esp. eccentric) contraction is beneficial
  • not endurance, stretching (short term)
  • 3-5% strain
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11
Q

Describe some of the changes that are likely with active loading (e.g. increased exercise) to: Muscle fibres

A
  • Endurance training- changes from type II to I (due to exercise)
  • Have changes due to genetics (predisposed)
  • Type II- easily fatiguable
  • Type I (slow twitch)- smaller force generated but able to be sustained
  • Muscle changes occur faster (wraps up)
  • Tendon changes occur faster (after detraining)
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12
Q

What is sacropenia?

A

Loss of mean body mass

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13
Q

What are 7 changes in the musculotendinous unit that are likely with ageing?

A
  1. Muscle fibres decrease in number and size; greater change to type II
  2. Muscle fibre type transformation (fast –> slow)
  3. Myofilaments
    • reduce in single fibre max. force reduce in myosin protein content and function
    • Reduce in elasticity
  4. Mitochondria
    • Reduce in no of type II
    • Loss in enzyme content = decreased ability to create ATP from oxygen = type I fibres more affected (type I and IIa more oxydated)
  5. Excitation-contraction coupling
    • Disruption or uncoupling
    • Deficits in Ca2+ release
  6. Satellite cells reduce in number- less response to injury
  7. Adipose tissue infiltration
    • Where the muscle was –> increase pennation angle –> increase ability to transfer forces (can help a bit)
    • Fascicle length increase
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