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neuro final exam > Neuro weeks 14-15 (15-19) > Flashcards

Neuro weeks 14-15 (15-19) Flashcards

1
Q

Position of the center of total body mass

A

Center of Mass (COM)

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2
Q

Vertical projection of COM

A

Center of Gravity (COG) -

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3
Q

Area of the body in contact with the ground

A

Base of Support (BOS)

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4
Q

Postural stability achieved through control of

A

COG or COM within the BOS -a combination (intersection) of task, individual and environment- three components

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5
Q

Three important components of Postural stability- TIE

A
  • Task
  • Individual
  • Environment
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6
Q

Why is a traffic cone stable?

A

Because it has a Low COM & broad BOS. However if inverted it becomes very unstable - narrow base of support and high COM

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7
Q

Humans are like an inverted traffic cone - an inverted pyramid with narrow BOS with a relatively high COM. Cone of stability varies in size depending upon a number of factors

A

True

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8
Q

Posturally stability occurs as long as

A

COM stays within the cone of stability

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9
Q

Postural instability occurs when

A

COM falls outside cone of stability

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10
Q

Postural stability and the relationship between COM and the BOS relationship varies by Individual differences in height Distribution of weight- but varies by the

A

Task Environment Challenge of task depends upon the context in which it is performed (environment)

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11
Q

Postural stability is very dependent upon

A

The task and the context in which it is taking place. For instance sitting and using iPad give the person a larger BOS and low COG to that BOS. This is a very stable and safe situation.

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12
Q

When standing & using an iPad BOS will be

A

Narrow so easier for COG to be out of BOS but wide stance will improve BOS. This is intrinsically less safe but safety improved by the wider base of support.

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13
Q

Walking while using iPad, COG is now regularly moving out of the base of support so this position is

A

Least safe combination of task and environment for postural stability

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14
Q

Factors & limitations that define stability WaRM2

A
  • Weakness & lack of ROM seen in ageing
  • Ability to constrain ROM available to skeletal system
  • Ability to coordinate muscle action
  • Muscle strength
  • All seen in neural diseases & disorders
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15
Q

Postural sway is a way to assess factors that create

A

Limits to the cone of stability.

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16
Q

T/F- There is always a slight postural sway in a rest in standing

A

True

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17
Q

Factors that contribute to the magnitude of postural sway include: PtIBt PMt

A
  • Postural tone of extensors of LE & trunk (antigravity muscles)
  • Intrinsic stiffness of muscles
  • Normal background tone
  • Postural alignment
  • Muscle tone - resistance of muscles to movement
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18
Q

How is normal postural alignment measured?

A

With a plumb line which should hang:

  • Through the mastoid process
  • Anterior to acromion
  • Through the hip joint
  • Anterior of center of knee
  • Anterior to ankle joint
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19
Q

Intrinsic muscle tone due to tissue heating.

A

Thixotropic properties of muscle

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20
Q

A characteristic of long proteins or other long chain molecules that produces a stiffness or cohesion simply from the nature of the interaction of the proteins.

A

What is Thixotropy

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21
Q

Example of Thixotropy

A

Tip up a bottle of ketchup and nothing comes out. Now Shake it and it will flow at least better if not freely. If it is cold it will not flow but if warm it is more likely to flow. So the shaking and the heating has lessened the molecular cohesion and made it less stiff. This is also one of the explanations for decreased muscle stiffness and increase ROM following message

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22
Q

Thixotropic properties of muscle lead to the following characteristics of muscle:

A
  • More pliable when stretched or with repetitive movement than when held rigid
  • More pliable when warmed up than when cold may be related to density of ground substance of connective tissues in muscle or density of cytoplasm of muscle cells
  • Thixotropic properties of muscle also explains the decreased muscle stiffness and increase ROM following message or tissue heating.
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23
Q

Intrinsic muscle tone also due to:

A

Spontaneous Ca++ release so constant actin-myosin activity in muscle Postural reflexes and activity of muscle spindles & Golgi tendon organs & various cutaneous afferents ending on lower motor neurons

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24
Q

Postural tone is dependent upon- RAD

A
  • Reflexes
  • Afferent sensory activity,
  • Descending postural activity
  • Effect of somatosensory/proprioceptive afferents is seen by decrease postural tone following the cutting of dorsal roots
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25
Q

Postural tone - Effect of somatosensory/proprioceptive afferents - cutting dorsal roots

A
  • Decrease postural tone Head position either due to vestibular inputs to brainstem or neck proprioceptors (vestibulospinal or interspinal) Descending influences from brainstem which excite postural muscles (particularly the extra-pyramidal pathways)
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26
Q

Postural stability is promoted by

A

Muscle activity.

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27
Q

EMG activity during static postures include:TTIEGG

A
  • Tibialis posterior when gravity line anterior to ankle
  • Tensor fascia lata
  • Iliopoas
  • Erector spinae muscles BUT NOT hamstrings & quadriceps femoris muscles
  • Gastrocnemius- soleus
  • Gluteus medius BUT NOT gluteus maximus
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28
Q

Postural stability related to COM position & velocity of the COM movement. As velocity of the COM movement increases the amount of the deviation of COM that it takes to reach the stability limit

A

decreases

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29
Q

As velocity of COM movement increases the base of support

A

Also increase to maintain stability

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30
Q

T / F - When COM falls outside the BOS as a result of a sudden perturbation, postural compensatory strategies are needed to compensate for this imbalance or a fall will occur

A

True

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31
Q

Compensatory strategies include: CFF

A
  • Controlling postural sway
  • Feedback control
  • Feedforward Anticipatory Control
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32
Q

Responses to increasing magnitude of anteroposterior instability due to increasing amounts of perturbation: HAS

A
  • Hip strategy
  • Ankle strategy
  • Stepping strategy
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33
Q

When small or low velocity perturbations produce small or slow deviations of the COM out of the BOS the situation can be easily corrected for with the use of

A

Ankle Strategy pattern

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34
Q

Ankle Strategy,

A

When body sways forward the ankle goes into dorsiflexion. Muscle action must pull the body back posteriorly.

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35
Q

Ankle strategy is accomplished by

A

A series of muscle activations with the sequence of muscle activation beginning with gastrocnemius. This produces plantar flexion at the ankle and occurs within 80 msec after perturbation

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36
Q

The Sequence of muscle activation continues with hamstring activation Occurring at about

A

100 msec after the perturbation

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37
Q

Activation of paraspinals occur at about

A

120 msec following perturbation

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38
Q

If the body sways backward the ankles go into

A

Plantar flexion and Muscle action needs to pull the body forward

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39
Q

Distal to proximal sequence of muscle activation begins with

A

Tibialis anterior producing a dorsiflexion at the ankle at about 80 msec after perturbation

40
Q

Sequence of muscle activation continues with quadriceps femoris contraction at about

A

100 msec following perturbation

41
Q

Sequence of muscle activation ends with contraction of the

A

Abdominal muscles at about 120 msec following the perturbation

42
Q

When is ankle strategy initiated?

A

Whenever there is a small magnitude or slow velocity perturbation .

43
Q

Leaning backward produces a

A

Backward shift of the COM, which is corrected by bringing the COM back forward over the BOS. This is done by sequential contraction of the tibialis anterior, quadriceps femoris and finally the abdomnals

44
Q

Leaning forward produces a forward shift of the COM, which is corrected by

A

Bringing the COM back over the BOS- done by sequential contraction of the gastrocnemius/soleus, hamstring and then paraspinals in sequence.

45
Q

Greater magnitude or higher velocity perturbations producing large or fast deviations of the COM out of the BOS and that are greater than can be handled by the ankle strategy are corrected by:

A

Use of the Hip Strategy pattern

46
Q

In the Hip Strategy If the body sways forward & the COM goes forward, muscle action must

A

pull the COM back over the BOS

47
Q

A Sequence of muscle activation beginning with quadriceps femoris producing

A

knee extension within 80-90 msec following the perturbation

48
Q

Greater magnitude or higher velocity perturbations producing large or fast deviations of the COM out of the BOS and that are greater than can be handled by the ankle strategy are corrected by:

A

Use of the Hip Strategy pattern

49
Q

RTP: Hip Strategy In the Hip Strategy If the body sways forward & the COM goes forward, muscle action must

A

pull the COM back over the BOS

50
Q

RTP: Hip Strategy A Sequence of muscle activation beginning with quadriceps femoris producing

A

knee extension within 80-90 msec following perturbation

51
Q

RTP: Hip Strategy Sequence of muscle activation continues almost immediately by the contraction of the

A

Abdominals Producing a hip flexion pulling the COM back over the feet (BOS)

52
Q

RTP: Hip Strategy What happens If the body sways backward & the COM moves backwards,

A

Muscle action is needed to pull the COM forward

53
Q

RTP: Hip Strategy Sequence of muscle activation beginning with hamstrings produce knee flexion within

A

about 80-90 msec after perturbation, followed almost immediately by paraspinal activation which extends trunk pulling the COM back over the feet (BOS)

54
Q

RTP: Hip Strategy summary In HS If the body sways forward & the COM goes forward the Muscle action must pull the COM back over the BOS using what compensatory response

A

contraction of the quadriceps femoris producing a knee extension and contraction of the abdominals to push the COM backward.

55
Q

In HS If the body sways backward & the COM goes backward the Muscle action must pull the COM forward over the BOS using what compensatory response

A

Contraction of the hamstrings producing a knee flexion and contraction of the paraspinals to push the COM forward.

56
Q

RTP- Stepping Strategy In a Stepping Strategy.

A

When greater or higher velocity perturbation produces an even larger or faster deviation of the COM out of the BOS occur, the deviation may be so great that it cannot be compensated for by either the ankle or hip strategies. So the person steps forward or backward to widen the base of support

57
Q

RTP- Stepping Strategy Strategy selected for stepping gate depends upon

A

Environmental factors.

58
Q

Postural strategies are adaptive to

A

Different environmental conditions. For instance ankle strategy can be used for moderate perturbations on flat ground but on irregular or compliant surfaces, the person will have to move to higher level strategy sooner

59
Q

Adaptation to mediolateral perturbations occurs at

A

Hip & trunk because of little movement in those directions at knee & ankle.

60
Q

Pattern of response of mediolateral perturbations begins with . Monoarticular muscle response occur before biarticular muscles are activated

A

Head/trunk followed by hip with head movement opposite to hip movement

61
Q

When does monoarticular muscle response occur

A

Before biarticular muscles are activated

62
Q

T / F- A person must maintain Multidirectional Stability with a continuum of response patterns that control stability in the 360-degree continuum of possible perturbation directions. Each muscle can belong to more than one synergy or strategies.

A

True

63
Q

Within a synergy an individual muscle has a unique or fixed level of

A

Muscle activation for the different synergies

64
Q

How does humans adapt to perturbations?

A

by applying different motor strategies- People without neural pathology can shift relatively quickly from one postural movement strategy to another

65
Q

Repeated exposure to a given postural task causes people to

A

Refine their response characteristics to optimize response efficiency.e.g. by the end of a bus ride strategies and shift in strategies are well worked out so are initiated in a quicker and smoother way than at the beginning of the bus ride

66
Q

Response to perturbation requires the use of multiple sensory systems which include- VSV

A

Vestibular, Somatosensory System - Proprioception, Vision input

67
Q

Which is the most valuable sensation in maintaining balance.

A

Peripheral (ambient) vision

68
Q

Provides a principle vertical frame of reference and can easily determine the magnitude of deviation of the head and body from that position. It also provides a horizontal frame of reference about how fast the person is approaching the horizontal frame of reference.

A

Ambient vision

69
Q

Ambient Vision integrates information about

A

Horizontals and verticals in the context of gravitational forces which is the integration that is important in maintaining balance

70
Q

In the context of balance

A

The visual system determines the amount of total motion, but the brain interprets all motion perceived through vision as self motion- the visual system is not good at differentiating exocentric motion from egocentric (self motion). evident when you are stopped at a traffic light next to a large bus or truck. If it moves forward you sense that you are moving backward before you realize that you are not.

71
Q

exocentric motion

A

object motion

72
Q

Ambient (peripheral) vision gives information needed in

A

Balance- as a person moves, the optical flow field radiates outward from a distant point central point

73
Q

Optic flow is spatially coincident with

A

Direction of motion.

74
Q

Optic flow arises from a point projected to the center of the

A

Retina where the distant point is perceived

75
Q

At the peripheral edges of the field of view, the optical flow field is

A

Nearly parallel to the line of motion and has been termed “lamellar flow” as opposed to “radial flow”

76
Q

T / f- People are NOT sensitive to moving environment.

A

False people are sensitive- this can be demonstrated by moving visual surround around the individual

77
Q

Postural adjustments occur as a result of

A

Movement of the surrounding environment -can be simulated by moving room experiments in which the person stands stable but the walls of the room are moved around the subject causing Increased Postural sway

78
Q

What happens when the room is moved forward?

A

The person perceives a backward motion and contracts muscle to pull themselves forward

79
Q

What happens when the room is moved backward?

A

The person will perceive a forward motion and contract muscle to pull themselves backward

80
Q

Active movement through the environment is viewed differently than passive movement (sitting with moving field of reference using video). More information is gained when active locomotion is involved

A

T

81
Q

Other vision factors that play a role in balance and falling.

A

Visual acuity and Depth perception (stereopsis). increased risk of falling when decreased

82
Q

Contrast Sensitivity Preliminary evidence suggest that the ability to distinguish varying levels of brightness against a constant background perhaps plays the greatest role in balance. Studies show that distant contrast sensitivity and depth perception are independent predictors of increased sway in older people

A

T

83
Q

Contrast Sensitivity

A

Poor contrast sensitivity add more risk in ambulation and people with poor contrast detection may have less capacity to detect ground-level hazards

84
Q

Types of balance tests CDP

A

Wide variety of balance tests- Computerized Dynamic Posturography (CDP)testing system that tests for the specific sensory deficits involved in balance disorders

85
Q

Computerized Dynamic Posturography includes: Isolation and quantification of

A

Orientation inputs from the visual, vestibular and somatosensory systems Central integrating mechanisms for selecting functionally appropriate orientation sense(s) Functionally appropriate movement strategy(s) in a variety of controlled task conditions Motor output mechanisms for generating timely and effective postural movements

86
Q

In Computerized Dynamic Posturography testing

A

Patient stands on a movable, dual forceplate support surface within a moveable surround (enclosure) Under control of a computer, the force platform can either move in a horizontal plane (translate), or rotate out of the horizontal plane (yaw) Standardized test protocols have support surface and visual surround motions, during which the patient’s postural stability and motor reactions are recorded

87
Q

Standardized test protocols for CDP include: SAM

A

Sensory Organization Test (SOT) Motor Control Test (MCT) Adaptation Test (ADT)

88
Q

Sensory Organization Test

A

Objectively identifies problems with postural control by assessing the patient’s ability to make effective use of (or suppress inappropriate) visual, vestibular, and proprioceptive information. Patients stand on a support surface that measures postural sway

89
Q

Sensory Organization Test controls the sensory information available to the patient Sensory input from

A

Feet and ankles is effectively eliminated through calibrated “sway referencing” of the support surface, Visual sensory input is effectively removed by calibrated “sway referencing” of the support surface with the visual surround

90
Q

The device will directly follow the patient’s anteroposterior body sway therefore eliminating orientation information through support surface tilt and/or visual surround will

A

challenge the patient’s ability to maintain their stability

91
Q

Sensory Organization Test utilizes 6 conditions including

A

With and without ankle tilt With and without vision and With sway referenced vision (distorted vision)

92
Q

Condition 1

A

Eyes open, fixed surface and visual surround so when platform moves horizontally there is normal vision, vestibular & ankle proprioception feedback

93
Q

Condition 2

A

Eyes closed, fixed surface So when platform moves horizontally there is no visual feedback but normal vestibular & ankle proprioceptive feedback

94
Q

Condition 3

A

Eyes open, fixed surface, sway referenced visual surround So when platform moves horizontally there is abnormal visual feedback but normal vestibular & ankle proprioceptive feedback

95
Q

Condition 4

A

Eyes open, sway referenced surface, fixed visual surround So when platform moves horizontally there is normal vision & vestibular feedback but abnormal ankle proprioceptive feedback

96
Q

Condition 5

A

Eyes closed, sway referenced surface So when platform moves horizontally there is no vision, abnormal ankle proprioception & normal vestibular input

97
Q

Condition 6

A

Eyes open, sway referenced surface and visual surround So when platform moves horizontally there is abnormal vision & proprioceptive ankle feedback & normal vestibular feedback

neuro final exam (10 decks)

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