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Neuro > Chapter 10 > Flashcards

Chapter 10 Flashcards

1
Q

What does well coordinated or learned movement require?

A

a continuous integration of visual, somatosensory and vestibular information with motor processing

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2
Q

What is feedforward?

A

anticipatory use of sensory information to prepare for movement

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3
Q

What is feedback?

A

refers to the use of sensory information during or after movement to make corrections either to the ongoing movement or to future movements

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4
Q

What does neural activity begin with?

A

a decision made in the anterior part of the frontal lobe

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5
Q

What is the second step in motor planning?

A

motor planning areas are activated, followed by control circuits

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6
Q

What regulates the activity in upper motor neuron tracts?

A

control circuits, consisting of the cerebellum and basal ganglia

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7
Q

Where do upper motor neuron tracts deliver signals?

A

to spinal interneurons and lower motor neurons (LMN)

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8
Q

What does the LMNs do?

A

signals directly to skeletal muscles, eliciting the contraction of muscle fibers that move the upper limbs and fingers

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9
Q

How is voluntary movement controlled?

A

from the top down (the brain, to the spinal cord, to the muscle)

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10
Q

What four systems make essential and distinct contributions to motor control:

A
  1. local spinal and brainstem circuits
  2. Descending control pathways
  3. the cerebellum
  4. basal ganglia
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11
Q

Motor cortex

A

planning, initiating, and directing voluntary movements

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12
Q

Brainstem centers

A

basic movements and postural control

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13
Q

Basal ganglia

A

gating proper initiation of movement

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14
Q

Cerebellum

A

sensory motor coordination of ongoing movement

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15
Q

When is muscle contraction produced?

A

when actin slides relative to myosin

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16
Q

What does the resistance to stretch muscles depend on?

A

the length

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17
Q

What determines the total resistance to muscle stretch?

A

active contraction, titin and weak actin-myosin bonds

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18
Q

What is muscle tone?

A

resistance to a passive stretch in a resting muscle

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19
Q

How is muscle tone assessed clinically?

A

passive rotation of a limb through a range of motion

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20
Q

What happens when muscle tone is normal?

A

resistance to passive stretch is minimal

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21
Q

What is normal resting muscle tone provided by?

A

weak actin-myosin bonds

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22
Q

When do sarcomeres disappear from the ends of myofibrils?

A

when healthy innervated muscle is continuously immobilized in a shortened position

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23
Q

When will the muscle add new sacromeres?

A

if the muscle is immobilized in a length position

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24
Q

What is cocontraction?

A

refers to the simultaneous contraction of antagonist muscles, increasing the joint’s resistance to movement

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25
Q

What does cocontraction do?

A

stabilizes joint

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26
Q

What does cocontraction do in the upper limbs?

A

enables precise movements

27
Q

What does cocontraction do in the lower limbs?

A

allows an individual to stand on an unstable surface

28
Q

What are two types of LMSs

A

alpha and gamma

29
Q

What do alpha and gamma neurons do?

A

only neurons that convey signals to extrafusal and intrafusal skeletal muscle fibers

30
Q

Where do axons of alpha motor neurons project?

A

extrafusal skeletal muscle, branching into numerous terminals as they approach muscle

31
Q

Where do axons of gamma motor neurons project?

A

to intrafusal fibers in the muscle spindle

32
Q

What to gamma motor neurons consist of?

A

medium sized myelinated axons

33
Q

What is alpha-gamma coactivation?

A

alpha and gamma motor neurons function simultaneously

34
Q

Why does alpha-gamma coactivation occur?

A
  • sources of input to alpha MN have collaterals MN

- less excitation needed to reach threshold gamma MN

35
Q

Motor unit:

A

An alpha motor neuron AND the muscle fibers it innervates”, constituting a functional entity

36
Q

Features of Motor units:

A

vary in degree of fatigability
in speed of contraction
in size

37
Q

How are motor units classified:

A

slow-twitch fibers

fast-twitch fibers

38
Q

Slow twitch fibers:

A

innervated by smaller-diameter, slower-conducting alpha motor neuron; involved in standing

39
Q

Fast twitch fibers:

A

innervated by larger-diameter, faster-conducting motor neuron; involved in walk and run etc

40
Q

In most movements, which fibers are activated first?

A

slow twitch fibers are activated first due to smaller cell bodies

41
Q

What is the Size Principle?

A

The order of recruitment from smaller to larger motor neurons

42
Q

When are movements generated?

A

when somatosensory information is integrated with descending motor commands in the spinal cord

43
Q

What are LMN pools?

A

groups of cell bodies in the spinal cord whose axons project to a single muscle

44
Q

What do medially located pools innervate?

A

axial and proximal muscles

45
Q

What do laterally located pools innervate?

A

distal muscles

46
Q

What do anteriorly located pools in ventral horn innervate?

A

extensors

47
Q

What do posteriorly located pools innervate?

A

flexors

48
Q

What is reciprocal inhibition?

A

the inhibition of antagonist muscles during agonist contraction

49
Q

How is reciprocal inhibition achieved?

A

by interneurons in the spinal cord that link lower motor neurons into functional group

50
Q

What is central pattern generators?

A

basic pattern of coordinated rhythmical activity (walking) wired into the spinal cord circuits

51
Q

What is a stretch reflex?

A

a mechanism to monitor and maintain muscle length

52
Q

What does a stretch reflex stimulate?

A

stretch of the muscle

53
Q

What is the senor of a stretch reflex?

A

spindles

54
Q

What does a stretch reflex involve?

A

alpha (and gamma) motor neurons, local circuit interneurons, and afferent somatic sensory input

55
Q

What is the golgi tendon organ reflex?

A

a system that monitors and maintains the muscle force

56
Q

What is the stimulus of the golgi tendon organ reflex?

A

tension due to muscle contraction

57
Q

What is sensor for the golgi tendon organ reflex?

A

golgi tendon organ

58
Q

What is a flexion withdrawal reflex?

A

a system for withdrawing the limb from a harmful stimulus

59
Q

What is the activation of the flexion withdrawl reflex?

A

activation of nociceptor

60
Q

What is the sensor of flexion withdrawal reflex?

A

sensor endings in skin, etc

61
Q

How is the golgi tendon organ reflex a negative feedback?

A

Functionally, the system can protect potential damage and prevent muscle fatigue

62
Q

What is the Hoffman or H-reflex?

A

Are monosynaptic reflexes elicited by electrically stimulating a nerve

63
Q

What is the purpose of the Hoffman or H-reflex?

A

to quantify the level of alpha motor neuron facilitation or inhibition

Neuro (23 decks)

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