Motor Physio Flashcards

1
Q

Cortical reflexes

A
  • Hopping

- Placing

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2
Q

Midbrain/Brainstem reflexes

A
  • Suckling
  • Vestibular
  • Righting
  • Yawn
  • Head/eye mvmts
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3
Q

Spinal reflexes

A
  • Stretch (myotatic)
  • Golgi tendon
  • Crossed extensor
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4
Q

How to tell b/w reflex and volitional mvmt?

A

Speed!

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5
Q

Components of intrafusal fibers in muscle spindle?

A

Motor and sensory

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6
Q

Sensory portion of intrafusal fibers?

A
  • NOT contractile
  • Portion sensitive to length
  • 2 sensors (nuclear bag fiber and nuclear chain fiber)
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7
Q

Primary afferent in intrafusal fibers

A
  • Ia fiber (large and myelinated)
  • innervates both nuclear bag and nuclear chain
  • Sensitive to length of muscle and how fast length is changing
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8
Q

Secondary afferent in intrafusal fibers

A
  • Group II fiber (smaller, myelinated)
  • innervates ONLY nuclear chain
  • Sensitive to length of muscle ONLY
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9
Q

Motor Efferent of intrafusal fibers

A
  • Gamma MN innervates
  • Controls length of muscle
  • same histo as skeletal m.
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10
Q

What happens when the intrafusal muscles are contracted?

A

Sensory portion is stretched –sensory portion is more sensitive to superimposed stretch

*Overall length is NOT changing though

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11
Q

Characteristics of myotatic reflex pathway?

A
  • Contraction(shortening) of stretched muscle
  • Protects muscle from tearing
  • Initiated by muscle spindle
  • Monosynaptic/segmental
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12
Q

Characteristics of Golgi tendon reflex?

A
  • Sudden/abrupt relaxation of contracted m.
  • Protects muscle from damage d/t excess force
  • Initiated by GTO
  • Polysynaptic/segmental
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13
Q

GTO

A
  • Innervates tendon
  • Bare nerve endings
  • APs increase with increased tension
  • Ib fiber to SC
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14
Q

Spinal Shock

A
  • d/t transection of SC
  • All reflexes abolished, even w/ intact circuit
  • Hyperpolarization of spinal neurons d/t loss of excitatory input from cortex
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15
Q

Decorticate Posturing

A
  • Flexed UE
  • Extended LE
  • Common cause = CVA @ internal capsule
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16
Q

Decerebrate posturing

A
  • Contraction of all anti-gravity muscles (UE extended)
  • ## Loss of input from all structures rostral to pons/caudal to red nucleus
17
Q

Rigidity

A
  • Resists motion in all directions d/t maintained muscle contraction
  • Continuous activation of gamma MNs
18
Q

Spasticity

A
  • Resists motion in a given direction d/t hyperactive myotatic reflex
  • Continuous activation of gamma MNs (contracts intrafusal muscles – lengthens nuclear bag/chain
19
Q

Spasticity and reflexes

A
  • Brainstem facilitory region ACTIVATES gamma MNs (spindle more sensitive)
  • spontaneously active
  • Brainstem inhibitory region INHIBITS gamma MNs (spindle less sensitive)
20
Q

Spasticity and cortical damage

A
  • Brainstem inhibitory region is lost … brainstem facilitory region predominates – uncontrolled brainstem facilitory region have stretch reflexes that fight passive motion