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KIN 380 > FINAL > Flashcards

FINAL Flashcards

1
Q

What are the 3 Essential Requirements of Locomotion?

A

Progression
Postural Control
Adaptability

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2
Q

What is progression?

A

coordinating patterns of muscle activity to move the body in a desired direction

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3
Q

What is postural control?

A

maintaining postural orientation and stability for locomotion

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4
Q

What is adaptability?

A

– meeting desired locomotor goals across a variety of task and environmental contexts

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5
Q

What is the “gait cycle”?

A

the events that occur between initial contact (i.e., heel strike) of one foot and the subsequent initial contact (i.e., heel strike) of the same foot

During each gait cycle (100%), the lower limb undergoes a stance phase (60%) and a swing phase (40%)

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6
Q

What is the stance phase?

A

Heel strike to toe-off (i.e., foot is in contact with the ground)

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7
Q

What are the sub-phases of the stance phase?

A

initial contact (heel strike) -> loading phase -> mid-stance -> terminal stance
Double support (10%) -> Single-support (40%) -> Double Supp (10%) -> Single-supp (40%)

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8
Q

What is the goal of the stance phase?

A

– generate vertical forces (postural control) and horizontal forces (progression) against the support surface in a manner that is sufficiently flexible to accommodate a variety of tasks and environmental characteristics (adaptability)

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9
Q

What is the swing phase?

A

Time between toe-off and heel strike (i.e., when the foot is not in contact with the ground)

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10
Q

What are the sub-phases of the swing phase?

A

initial swing -> mid-swing -> terminal swing

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11
Q

What is the goal of the swing phase?

A

advancement (progression) and repositioning (postural control) of the lower limb in a manner that is sufficiently flexible to allow for foot clearance in a variety of task and environmental contexts (adaptability)

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12
Q

The part of the gait cycle in which both feet are on the ground is termed _________.

A

Double stance

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13
Q

What are the gait patterns?

A

Kinematic patterns (spatiotemporal)

Kinematic patterns (Joint rotations/COM)

Muscle Activation Patterns

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14
Q

What is the step portion of Kinematic patterns (spatiotemporal)?

A

process of moving one limb forward

Step length: distance from the heel strike of one foot to the subsequent heel strike of the other foot

Step time: time required to take one step

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15
Q

What is the stride portion of Kinematic patterns (spatiotemporal)?

A

process of making one step with each foot (i.e., completing one gait cycle)

Stride length: distance from the heel strike of one foot to the subsequent heel strike of the same foot

Stride time: time required to take one stride

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16
Q

What is the cadence portion of Kinematic patterns (spatiotemporal)?

A

number of steps per unit time (e.g., 120 steps/min)

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17
Q

What is the speed portion of Kinematic patterns (spatiotemporal)?

A

verage distance traveled per unit time (e.g., 1.4 m/s, 4.6 ft/s)

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18
Q

An individual’s preferred walking speed is the speed that requires what?

A

minimal energy expenditure

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19
Q

As we increase walking speed what variables of Kinematic patterns (spatiotemporal)?

A

both stance and swing time decrease, but stance phase becomes progressively shorter relative to swing phase

60/40 Stance/Swing ratio for walking switches to 40/60 for running (double support disappears)

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20
Q

As we decrease walking speed what variables of Kinematic patterns (spatiotemporal)?

A

stance time gets longer, while swing time stays relatively constant

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21
Q

What is the Kinematic Patterns (Joint Rotations/COM)?

A

There are characteristic kinematic patterns that occur during the gait cycle

The combined effect of the individual pelvic and lower limb joint rotations is a smooth forward progression of the body’s centre of mass (COM)

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22
Q

What 2 characteristics are involved in Kinematic Patterns (Joint Rotations/COM)?

A

Vertical
Mediolateral

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23
Q

What is the vertical characteristic in Kinematic Patterns (Joint Rotations/COM)?

A

Maximum: midpoint of single-support
Minimum: midpoint of double-support

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24
Q

What is the mediolateral characteristic in Kinematic Patterns (Joint Rotations/COM)?

A

Maximum right: midpoint of right limb stance
Maximum left: midpoint of left limb stance

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25
Q

Several key determinants function to minimize vertical displacement of the COM (what are they)?

A

Pelvic rotation, lateral pelvic displacement, knee flexion, knee/ankle coordination

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26
Q

What are the limitations of Kinematic Patterns and Energy Expenditure During Gait?

A

Studies have shown that some of the projected key determinants do not impact vertical displacement of the COM

Lower limb joints must undergo large motions and torques to maintain a level COM path, which increases the required energy expenditure

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27
Q

More recently, it has been suggested that reducing energy expenditure associated with?

A

with gait requires smooth mechanical transfer of kinetic and gravitational energies (involves up-down movement of COM)

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28
Q

What is the inverted pendulum model?

A

The stance leg essentially acts as an inverted pendulum that the COM vaults over

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29
Q

What is Potential energy (gravitational)?

A

energy possessed by an object due to the height of its COM

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30
Q

What is kinetic energy?

A

energy possessed by an object due to its motion

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31
Q

What is Law of Conservation of Mechanical Energy?

A

“energy cannot disappear” (in a closed system)

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32
Q

What is
Midpoint of single-support?

A

MAX potential energy, MIN kinetic energy

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33
Q

What is Midpoint of double-support?

A

MIN potential energy, MAX kinetic energy

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34
Q

T or F: Smooth vertical sinusoidal fluctuations in COM position results in an efficient and ongoing transfer between potential energy and kinetic energy?

A

True

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35
Q

Muscle Activation Pattern: What is the goal of the stance phase?

A

generate vertical forces (postural control) and horizontal forces (progression) against the support surface

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36
Q

What are the phases involved in postural control?

A

Initial contact

loading phase

mid-stance and terminal stance

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37
Q

What is initial contact?

A

ground reaction force creates an ankle plantarflexion and knee flexion moment

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38
Q

What is loading phase?

A

eccentric contractions of the ankle dorsiflexors and knee extensors resist the GRF-induced moments

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39
Q

What is Mid-stance & terminal stance?

A

contraction of the hip abductors maintains pelvic stability; contractions of the hip extensors and knee extensors maintain lower limb stability

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40
Q

What is the progression of muscle activation patterns?

A

Mid-stance & terminal stance: contraction of the ankle plantarflexors (and hip extensors) propels the body over the foot

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41
Q

The ankle plantarflexors are responsible for?

A

a majority of the propulsive force generated during the stance phase

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42
Q

Muscle Activation Pattern: What is the goal of the swing phase?

A

advancement (progression) and repositioning (postural control) of the lower limb

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43
Q

Muscle Activation Pattern: What is the progression of the swing phase? - initial swing

A

Initial swing: contraction of the hip flexors propels the lower limb forward, contraction of the hip flexors and ankle dorsiflexors shortens the lower limb (clearance)

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44
Q

Muscle Activation Pattern: What is the postural control of the swing phase? - terminal swing

A

Terminal swing: eccentric contraction of the hip extensors slows the lower limb, contraction of the ankle dorsiflexors prepares the foot for heel strike

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45
Q

What are the adaptations of gait and why?

A

Involves adapting the strategies used to accomplish progression and postural control in the face of changing task and environmental conditions

Reactive postural control for unexpected perturbations

Anticipatory postural control for expected disturbances

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46
Q

What is the reactive portion of adaptation of gait?

A

Reactive postural adjustments are integrated into step cycle during recovery from unexpected perturbations

Distal perturbed leg muscles and hip and trunk muscles play a role

Arm movements commonly used during balance recovery in gait and for protection

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47
Q

Most falls in the elderly occur as a result of a?

A

trip or fall

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48
Q

Most falls in the elderly occur as a result of a?

A

trip or fall

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49
Q

Strategy used for balance recovery depends on?

A

where in the step cycle the trip occurred

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50
Q

What is the early swing phase?

A

elevate swinging limb

Flexor torque through the swinging limb to lift higher

Extensor torque in stance limb to increase height of body

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51
Q

What is the late swing phase?

A

lower swinging limb
Plantarflexion of ankle in swinging limb

Knee extension in swing limb to reach down

Shortened step length

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52
Q

What is the anticipatory factors of adaptation of gait?

A

Prediction is used to minimize destabilizing forces

e.g., APAs to movement of own limbs (develop with experience)

Visually activated strategies modify gait in response to perceived threats

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53
Q

What is Obstacle Crossing factor?

A

Higher obstacle, greater range of COM movement in anteroposterior and vertical directions, but not mediolateral

Keeps COM within safe limits

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54
Q

What is Surface conditions (slippery) factor?

A

Reduce stance duration and loading speed

Shorter stride length

Increase muscle stiffness (compliant)

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55
Q

What is the incline factor?

A

Increased muscle activity

Longer step lengths and reduced cadence (uphill)

Shorter step lengths and higher cadence (downhill)

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56
Q

What is the incline factor?

A

Increased muscle activity

Longer step lengths and reduced cadence (uphill)

Shorter step lengths and higher cadence (downhill)

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57
Q

What is the turning factor?

A

Depends on front foot
Right turn with right foot in front = “spin turn”

Left turn with right foot in front = shift weight to right leg, externally rotate left hip and step onto left leg and turn until right leg steps in new direction (“step turn”)

Step turn more stable

Deceleration prior to turn uses ankle strategy

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58
Q

What are rhythmic movements?

A

Repetitive performance of the same motor act

Flying, breathing, swallowing, vomiting, locomotion

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59
Q

What are Central Pattern Generators (CPGs)?

A

The basic pattern for rhythmic movements thought to be controlled by oscillating circuits within the spinal cord (CPGs)

Non-rhythmic movements thought to be under greater cortical control

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60
Q

Where are Central Pattern Generators (CPGs)?

A

Transect the CNS at various points and observe locomotion to identify contributions of different parts of motor system

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61
Q

What is Decorticate (“no cortex”) preparation?

A

basal ganglia, cerebellum, brainstem, spinal cord intact

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62
Q

What is Decerebrate (“no cerebrum”) preperation?

A

cerebellum, brainstem, spinal cord intact

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63
Q

What is Decerebrate (“no cerebrum”) preperation?

A

cerebellum, brainstem, spinal cord intact

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64
Q

What is Spinal preparation?

A

spinal cord only intact

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65
Q

How do Central Pattern Generators (CPGs) work? - Half-Centre Model

A

Reciprocal inhibitory circuits underlie the rhythmicity

Flexor-extensor “half-centres”

Both receive descending and ascending input but once initiated, no further inputs are needed

Half-centres are connected to each other through inhibitory interneurons

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66
Q

What are the 3 steps of the half-centre model?

A

1) The CPG will be initiated through the activation of neuron A or B (whichever is closest to threshold)

2) If A is active, it drives neuron C and inhibits neuron B

3) Discharge of A slowly declines (hyperpolarization, neurotransmitter depletion)

4) Reduced inhibition to B eventually turns B on (post-inhibitory rebound)

5) When B is active, it drives neuron D

The end result is a process that “cycles” back and forth and generates rhythmic alternating flexion and extension movements

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67
Q

The rhythmic pattern generated by the CPG is analogous to?

A

activity generated by the crossed extensor reflex (is elicited when a flexor withdrawal reflex is activated)

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68
Q

Although CPGs can produce this rhythmic stepping pattern, supraspinal and sensory inputs are required for?

A

weight support, dynamic postural stability, and adaptation

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69
Q

Although CPGs can produce this rhythmic stepping pattern, supraspinal and sensory inputs are required for?

A

weight support, dynamic postural stability, and adaptation

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70
Q

Parts of the brain for CPGs?

A

Cerebellum
-Weight support and -improved coordination

Basal Ganglia
-Dynamic postural stability
-Initiation of gait

Cerebral Cortex
-Adapt the pattern to task/environmental demands
-Feedforward (predictive) control
-Exerts influence through corticospinal pathway

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71
Q

How is a CPG “turned on” in the intact CNS?

A

Descending drive from the brain

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72
Q

How is a CPG “turned on” experimentally?

A

Stimulating area of brainstem or midbrain

Stimulating cutaneous afferents

Apply exogenous excitatory neurotransmitter

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73
Q

What is Neonate walking?

A

Step-like movements in newborn infants when corticospinal tract development is incomplete

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74
Q

What is Rhythmic leg movements?

A

in spinal cord injured patients
Evoked by cutaneous and spinal cord stimulation

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75
Q

What is Sleep related periodic leg movements?

A

in locomotor rhythm

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76
Q

What are Vibration-induced air stepping?

A

Vibrate one or both limbs in neurologically intact subjects and evoke rhythmic activation of hip and knee in simulated weightlessness

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77
Q

What are Vibration-induced air stepping?

A

Vibrate one or both limbs in neurologically intact subjects and evoke rhythmic activation of hip and knee in simulated weightlessness

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78
Q

T or F: Rhythmic pattern can be produced without any continuing sensory feedback? Why?

A

True

CPG can be strongly influenced by signals from peripheral sensory receptors

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79
Q

How do Sensory signals contribute to maintenance of rhythmic activity?

A

Without sensory feedback (i.e., de-afferented cat), the frequency of rhythmic activity generated by the CPG slowly declines until it stops

If sensory system intact, rhythmic activity continues

Evidence: Rhythmic activity does not last in de-cerebrate AND de-afferented cats

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80
Q

How do Sensory signals initiate phase transitions?

A

Cutaneous and proprioceptive signals inform when switch from stance to swing occurs

Evidence: Prevent hip extension to prolong stance phase and the rhythmicity stops

CPG circuit is waiting for sensory feedback to inform whether it is time for the phase transition

CPG requires feedback to indicate hip is in position and limb is unloading before going from stance to swing

81
Q

How do Sensory signals initiate phase transitions?

A

Cutaneous and proprioceptive signals inform when switch from stance to swing occurs

Evidence: Prevent hip extension to prolong stance phase and the rhythmicity stops

CPG circuit is waiting for sensory feedback to inform whether it is time for the phase transition

CPG requires feedback to indicate hip is in position and limb is unloading before going from stance to swing

82
Q

How do Sensory signals regulate magnitude of motor activity?

A

Somatosensory signals inform amplitude of muscle activity required

Evidence: Blockade of muscle spindle activity in ankle extensors results in a 50% reduction in EMG activity generated by CPG during stance

Indicates that the stretch reflex contributes to force production during stance

83
Q

How do Sensory signals allow adaptation of the normal motor pattern to environment?

A

Stumbling corrective response” – elevate swinging limb

Combination of muscle (spindles, GTOs) and cutaneous afferents

Evidence: Stimulating a cutaneous nerve on the top of the foot (superficial peroneal nerve) generates the same muscle activity observed during a stumble

Activity generated depends on leg position (mimicking early or late swing)

84
Q

How are reflexes modulated?

A

Reflexes are modulated from descending (brain), spinal (CPG), and afferent sources

85
Q

What is Task-dependent modulation?

A

Reflexes in the legs are affected by movement of the arms

Indicates an inter-limb connection for reflex modulation

86
Q

What is phase-dependant modulation?

A

H-reflexes are progressively inhibited from sitting to standing to walking to running

87
Q

What is reflex reversal?

A

Reflexes can be excitatory in one circumstance and inhibitory in another

GTOs activate inverse stretch reflex (inhibit active muscle) in non-dynamic condition but activate excitatory reflex during stance in locomotion

Cutaneous reflexes switch from excitatory to inhibitory across the gait cycle

How? Complex interneuron connectivity

88
Q

What is reflex reversal?

A

Reflexes can be excitatory in one circumstance and inhibitory in another

GTOs activate inverse stretch reflex (inhibit active muscle) in non-dynamic condition but activate excitatory reflex during stance in locomotion

Cutaneous reflexes switch from excitatory to inhibitory across the gait cycle

How? Complex interneuron connectivity

89
Q

Reflex modulation is a great way to move towards?

A

Gives ideas about how gait can be adapted to different task/environmental demands

90
Q

Challenges to Gait Obstacle Clearance?

A

Reactive - “stumble-corrective response”

Anticipatory – APAs and visually activated strategies to adjust for perceived threats

Learning and memory

Inter-limb transfer

Sensory systems

91
Q

With instruction to keep foot clearance as low as possible without touching the object + auditory feedback, people can learn to?

A

step over an object more effectively

EXS:
Treadmill

Foam sticks that passively fold back on touch

Auditory signal that indicates height of object clearance

92
Q

The learning associated with reduced object clearance heights transfers to what body part?

A

the trailing leg

Information gained during object crossing with the leading leg is transferred to trailing limb

93
Q

What is visual information in obstacle clearance?

A

Visual information about the obstacle configuration is used to select a context-specific locomotor program

Next a memory of the somatosensory signals associated with the crossing with the lead limb is created and transferred to regions supporting movement of the trailing leg

94
Q

What is visual information in obstacle clearance?

A

Visual information about the obstacle configuration is used to select a context-specific locomotor program

Next a memory of the somatosensory signals associated with the crossing with the lead limb is created and transferred to regions supporting movement of the trailing leg

95
Q

Obstacle Clearance and Dual-tasking?

A

Gait requires attention and the attentional resources required increases with added gait demands

People are more likely to contact an obstacle when simultaneously performing a cognitive task

Effect is greater when the secondary task introduced during “pre-crossing” vs “crossing”

Whether or not the gait task or the cognitive task is “prioritized” in terms of allocation of attentional resources is context-specific

Gait or a secondary task can be prioritized based on instructions

Gait will be prioritized with increasing challenge (i.e., higher obstacle height)

Cell-phone use seems to almost always receive priority over gait…

96
Q

What is the step portion of Kinematic Patterns (Spatiotemporal)?

A

process of moving one limb forward

Step length: distance from the heel strike of one foot to the subsequent heel strike of the other foot

Step time: time required to take one step

97
Q

What is the stride portion of Kinematic Patterns (Spatiotemporal)?

A

process of making one step with each foot (i.e., completing one gait cycle)

Stride length: distance from the heel strike of one foot to the subsequent heel strike of the same foot

Stride time: time required to take one stride

98
Q

What is the cadence portion of Kinematic Patterns (Spatiotemporal)?

A

number of steps per unit time (e.g., 120 steps/min)

99
Q

What is the speed portion of Kinematic Patterns (Spatiotemporal)?

A

average distance traveled per unit time (e.g., 1.4 m/s, 4.6 ft/s)

100
Q

Compared to younger adults, healthy older adults generally demonstrate? (kinematic patterns (spatiotemporal)

A

Decreased walking speed

Decreased step length

Increased step width

These 3 have Even further declines in elderly with history of falls ^

Increased stance phase time

Decreased swing phase time

Decreased single support time

101
Q

Compared to younger adults, healthy older adults generally demonstrate? (kinematic patterns (Joint rotations/COM))

A

Decreased rotations about the ankle, knee, and hip

Decreased vertical displacement of the COM (increased energy expenditure)

102
Q

Compared to younger adults, healthy older adults generally demonstrate? (muscle activation and joint kinetic patterns)

A

Increased co-activation (ankle dorsiflexors and plantarflexors in loading phase)

Decreased power absorption at heel strike (knee extensors)

Decreased power generation at toe off (ankle plantarflexors)

Decreased ability to co-vary lower limb segment moments to generate a net extensor support moment (for dynamic stability)

103
Q

Compared to younger adults, healthy older adults generally demonstrate? (Gait variability)

A

There is initial evidence that in groups of older adults similar for gait speed and muscle strength, differences in gait variability can predict falling risk

Too much or too little variability can indicate fall risk

104
Q

Generally, gait patterns used by healthy older adults are similar to those used by?

A

younger adults in challenging conditions (e.g., walking on a slippery surface)

Therefore, it has been suggested that gait changes in older adults may relate more to changes in postural control than locomotor control

105
Q

The rate of torque development is more important than what for balance recovery?

A

The rate of torque development is more important than muscle strength for balance recovery following a slip/trip

106
Q

Compared to younger adults, healthy older adults generally demonstrate the following in response to a slip/trip?

A

Slower onset latencies and decreased activity levels in the postural control muscles (i.e., slower rate of torque production)

Increased trunk motion and arm motion

107
Q

Anticipatory control of gait depends on the ability to modify gait patterns in response to?

A

visual cues related to obstacles and potentially destabilizing environmental conditions (e.g., slippery surface)

108
Q

Compared to younger adults, healthy older adults in Age-related changes in anticipatory control of gait generally?

A

Require more time to implement an appropriate response strategy

Use more conservative strategies for crossing over obstacles (e.g., slower approach speed, slower crossing speed, shorter crossing step length)

109
Q

Older adults with history of falls show greater what during obstacle crossing?

A

mediolateral COP displacement and velocity during obstacle crossing

110
Q

Age-related changes in dual task gait performance?

A

Reaction time to an auditory stimulus is increased (i.e., slower) during gait in older adults but shows no change in younger adults

The attentional demands of obstacle avoidance are increased compared to younger adults

Increased rate of obstacle contact when performing secondary task

Increased rate of error on cognitive task when simultaneously walking

Both pre-crossing and crossing phases are affected by dual-tasks in older adults

111
Q

*Balance confidence and fear of falling also relate to?

A

Control of gait

112
Q

Gait disorders often impact the?

A

the performance of activities of daily living and are one of the most debilitating consequences of neurologic pathology

113
Q

Type of gait disorder depends on?

A

Type and extent of neurologic pathology

Type and extent of impairments

Use of compensatory strategies

114
Q

How to classify gait disorders?

A

Patients commonly classified into patient sub-groups to assist in clinical decision-making (e.g., for determining treatment/intervention)

No single approach has universal acceptance

115
Q

2 common approaches to classifying gait disorders?

A

Diagnostic

Pathophysiological

116
Q

2 common approaches to classifying gait disorders?

A

Diagnostic

Pathophysiological

117
Q

What is the diagnostic approach?

A

(traditional)

Grouped on neurologic pathology

Limitation – same pathology, many gait patterns

118
Q

What is the pathophysiological approach?

A

(recent)

Describes specific impairments that impair gait (e.g., paresis, spasticity)

Advantage – tailor treatment to specific patients

119
Q

What is paresis (motor weakness)?

A

Motor cortex pathology (i.e., upper motor neuron lesion)

Stroke, cerebral palsy

UMN lesion -> decreased descending drive to lower motor neurons -> decreased motor unit recruitment -> weakness

120
Q

What happens to lower limb muscles during specific portions of the gait cycle?

A

Lower limb muscles contract both concentrically (i.e., generate movement) and eccentrically (i.e., control movement) during specific portions of the gait cycle

121
Q

Lower limb paresis can result in?

A

Inability to generate sufficient propulsive force (e.g., ankle plantarflexor paresis)

Inability to restrain unwanted motion (e.g., ankle dorsiflexor paresis causes the foot to drop after heel strike)

122
Q

What are the consequences and compensation of Plantar flexor paresis?

A

Reduced ankle plantarflexion at toe off = flat foot gait

Consequences: reduced limb velocity during swing, reduced step length, reduced walking speed

Compensation: increased hip flexor activity at toe off

123
Q

What are the consequences and compensation of Dorsiflexor paresis?

A

Consequences: Reduced ability to control ankle plantarflexion following heel strike = slap foot gait; Reduced ability to shorten the limb during the swing phase = drop foot gait

Compensation: excessive hip and/or knee flexion during swing = steppage gait

124
Q

What are the consequences and compensation of Knee extensor paresis?

A

Consequence: Reduced ability to control knee flexion during heel strike

Compensation: Forward trunk lean generates knee extension torque

Increases stability of knee during stance, but high stress on knee structure

125
Q

What are the consequences and compensation of Hip flexor paresis?

A

Reduced hip flexor
torque during swing phase
Consequence: reduced knee flexion and limb velocity during swing phase, reduced step length and walking speed

Compensation: circumduction, contralateral vaulting, contralateral trunk lean to help improve foot clearance during swing

126
Q

What are the consequences and compensation of Hip abductor paresis?

A

Reduced ability to control frontal plane rotation of pelvis during stance phase

Consequence: contralateral pelvic drop – “Trendelenburg gait”

Compensation: ipsilateral trunk lean to improve foot clearance during swing

127
Q

What is Trendelenburg gait?

A

Weak hip abductors cause hip to pop out to side

128
Q

Paresis of ankle plantarflexors and hip flexors have a major effect on?

A

walking speed

129
Q

After a stroke what happens with walking speed?

A

Correlation between walking speed and ankle plantarflexor moment, hip flexor moment generated at toe off in paretic limb

Ankle plantarflexor moment at toe off is most important variable for determining walking speed

130
Q

What happens to mobility when someone has Spasticity (hypertonia)? (Lots of info)

A

Motor cortex pathology (i.e., upper motor neuron lesion)

Stroke, cerebral palsy

UMN lesion -> decreased descending drive to lower motor neurons -> increased LMN stretch reflex excitability -> increased passive resistance to stretch

A spastic lower limb muscle demonstrates increased muscle activity during the portion(s) of the gait cycle in which the muscle is being lengthened (i.e., when the antagonist is contracting)

131
Q

What is the plantarflexor spastcity stance?

A

Dorsiflexion during terminal swing -> spastic ankle plantarflexors contract -> flat foot (or forefoot) initial contact rather than a heel strike

Continued contraction of ankle plantarflexors during stance causes the knee to be relatively extended and the foot to be relatively plantarflexed (“equinovarus”)

132
Q

What is the plantarflexor spastcity swing?

A

Extended knee in terminal stance impairs toe off (decreased propulsive force)

Continued contraction of ankle plantarflexors during the swing phase

133
Q

What is the consequence of Extended knee in terminal stance impairs toe off (decreased propulsive force)?

A

increased demand on hip flexors to propel the limb forward

134
Q

What is the consequence of Continued contraction of ankle plantarflexors during the swing phase?

A

Consequence: increased demand on hip and knee flexors to shorten the limb to prevent the foot from contacting the ground (e.g., toe drag)

135
Q

Some individuals demonstrate phase-dependent effects of locomotor spasticity. What is the swing and stance when this occurs?

A

Stance – increased lengthening velocity -> increased muscle activity

Swing – increased lengthening velocity -> no increased muscle activity

136
Q

What happens during hamstring spasticity? What is the consequence of it?

A

Hip flexion during the swing phase causes spastic hip extensors (knee flexors) to contract, which results in a flexed knee position at initial contact and in stance

Consequence: increased demand on knee extensors to prevent limb from collapsing during stance

137
Q

What is Rigidity (hypertonia) in mobility?

A

e.g., hypokinetic basal ganglia (Parkinson’s)

Stiff, slow, shuffling gait

138
Q

What are the coordination abnormalities of mobility? (Abnormal synergies)

A

Abnormal synergies (e.g., stroke): stereotyped abnormal patterns of coordinated muscle activity that occur during functional movements of the limbs, resulting in an inability to recruit muscles and control individual joints

139
Q

Abnormal synergies that occur during gait include?

A

Extension synergy: contraction of all extensor muscles during the stance phase

Flexion synergy: contraction of all flexor muscles during the swing phase

140
Q

What is coactviation oof coordination abnormalities?

A

Coactivation (e.g., stroke, cerebral palsy): Activation of agonist and antagonist muscles around a joint (this is normally minimized during gait)

141
Q

What is the Coordination abnormalities of Ataxia (e.g., cerebellar degeneration)?

A

impaired intersegmental coordination

142
Q

Characteristics of an “ataxic gait” include?

A

Wide-based and staggering

Irregular stepping pattern

Delays in the timing of specific events during the gait cycle (e.g., peak knee flexion during the swing phase)

143
Q

Characteristics of an “ataxic gait” include?

A

Wide-based and staggering

Irregular stepping pattern

Delays in the timing of specific events during the gait cycle (e.g., peak knee flexion during the swing phase)

144
Q

What are the musculoskeletal impairments of abnormal mobility?

A

Musculoskeletal impairments often develop secondary to neurological impairments

Ankle plantarflexor contracture: gait similar to plantarflexor spasticity

Knee flexor contracture: gait similar to hamstring spasticity

Hip flexor contracture: forward trunk lean during mid-stance and terminal stance

145
Q

What are Relevant techniques/modalities for abnormal gait?

A

LiteGait – Gait trainer
coordination/patternig, CPG activation, strengthening

Power Plate – Vibration trainer -tone, strengthening

Therasuit -patterning, strengthening

146
Q

What are the Sensory/perceptual impairments?

A

Somatosensory Deficits

Vestibular Deficits

Visual Deficits

147
Q

What are Somatosensory Deficits?

A

Impaired stance-swing transition

Wide-based and staggering gait

148
Q

What are Vestibular Deficits?

A

Impaired head stabilization (“blurred vision” during gait)

Slower walking speed and longer double-support time

149
Q

What are Visual Deficits?

A

Impaired anticipatory strategies (e.g., obstacle avoidance)

150
Q

What happens to mobility when someone has a cognitive impairment?

A

Individuals with a variety of neurological pathologies demonstrate impaired dual-task performance (e.g., stroke, Parkinson’s disease, traumatic brain injury)

Reduced walking speed

Impaired cognitive task performance

Individuals with cognitive impairments (e.g., dementia) demonstrate a slower walking speed and a higher rate of obstacle contact

151
Q

Reaching and grasping skills are vital to the performance of?

A

many activities of daily living

152
Q

Similar to other motor skills, control of reach and grasp involves?

A

Interaction between nervous system and musculoskeletal system

Contextual interaction between the individual, task, and environment

153
Q

Key components of reach and grasp skills include?

A

1) Locate the object
2) Reach for the object
3) Grasp the object

154
Q

Each of the components of reach and grasp skills involves?

A

Motor system – coordination eye and head movements (locate), coordinate arm and hand movements (reach and grasp)

Sensory/Perceptual systems – sensory input to locate and identify object; guide arm and hand movements

155
Q

Each of the components of reach and grasp skills involves?

A

Motor system – coordination eye and head movements (locate), coordinate arm and hand movements (reach and grasp)

Sensory/Perceptual systems – sensory input to locate and identify object; guide arm and hand movements

156
Q

What happens during the locating component of reach and grasp? (Possible issues along with it?)

A

Object location impacts movements required

Reduced ability to coordinate eye and/or head movements to locate objects could impact reach and grasp skills – train it!

Lesions affecting transmission of visual input can lead to a complete loss of portions of the visual field

157
Q

Lesions affecting processing of visual input can lead to?

A

Inability to attend to objects in half of the visual field

Visual neglect: lack of awareness of contralateral half of visual field

Visual extinction: unable to simultaneously detect stimuli in each half of the visual field

158
Q

Impaired ability to plan and control eye movements toward an object can cause what? (Give an example)

A

(e.g., problems breaking gaze fixation)

159
Q

What is the reaching for the object component?

A

Reaching movements are associated with joint coordination to achieve straight-line hand trajectories and bell-shaped velocity profiles (i.e., acceleration then deceleration)

Start slow – pick up speed – then slow back down

160
Q

The goal of the reach influences the?

A

velocity profile

161
Q

What components of reaching for the object affect the ratio of acceleration?

A

Reach to grasp something – decrease ratio of acceleration time to deceleration time

Pointing – increase ratio of acceleration time to deceleration time

Grasp and manipulate – decrease ratio of acceleration time to deceleration time

162
Q

Neurologic pathologies that affect movement planning and coordination can impair?

A

the hand trajectory during a reaching movement (e.g., timing, direction, magnitude)

163
Q

Multiple neurologic pathologies result in slowed reaction and?

A

movement times during reaching tasks (e.g., stroke, cerebral palsy, cerebellar degeneration, Parkinson’s Disease)

164
Q

What is Impaired inter-segmental coordination?

A

Various neurologic pathologies (especially cerebellar pathologies)

165
Q

Various neurologic pathologies (especially cerebellar pathologies) result in impaired intersegmental coordination during reaching tasks? (2)

A

Dysmetria -> undershooting slow movements, overshooting fast movements

Decomposition -> initial vertical (shoulder) and later horizontal (elbow) movement

166
Q

Individuals who have had a stroke demonstrate abnormal synergies (e.g., upper limb flexor synergy) that result in an impaired ability to?

A

Perform isolated joint movements

Selectively control individual joints

167
Q

An impaired ability to perform isolated joint movements explains most of the what?

A

variance in hand trajectory and end-point error during reaching movements in individuals who have had a stroke.

168
Q

What is involved in the grasping the object component?

A

Grip aperture refers to how “open” the hand is

During the reach, we spend MOST of the time opening the hand

Maximum grip aperture occurs ~5/6 into the reach, then closing begins

“Trigger” to signal hand closing seems to be mostly spatial

If uncertainty about object size, grip aperture is increased

168
Q

What is involved in the grasping the object component?

A

Grip aperture refers to how “open” the hand is

During the reach, we spend MOST of the time opening the hand

Maximum grip aperture occurs ~5/6 into the reach, then closing begins

“Trigger” to signal hand closing seems to be mostly spatial

If uncertainty about object size, grip aperture is increased

169
Q

When someone has Parkinson’s Disease what happens when grasping the object?

A

Associated with slower hand opening (i.e., bradykinesia) and smaller grip aperture during grasping tasks

Medication (levodopa) is associated with improved grasping movement performance (e.g., faster hand opening, wider grip aperture)

170
Q

When someone has Stroke what happens when grasping the object?

A

There is evidence that each cerebral hemisphere makes specific contributions to the control of reach and grasp tasks

171
Q

A study with stroke patients that measured impairments in the limb ipsilateral to the lesion found that (right and left hemispheric lesions)

A

Right hemispheric lesions: slower movement times and an impaired ability to coordinate reach and grasp movements

Left hemispheric lesions: delayed hand shaping movements and an impaired ability to appropriately scale grip aperture and grip forc

172
Q

What are the 2 parts included in functional lateralization?

A

Right and left hemispheres

173
Q

Two functional “streams” of parallel processing of visual information. What are they?

A

Dorsal and ventral streams

174
Q

Dorsal stream (where) contributions to visual system?

A

Posterior parietal lobe

Sub-conscious processing of spatial information related to object (e.g., position, size, orientation)

175
Q

Ventral stream (what) contributions to visual system?

A

Inferior temporal lobe

Conscious perception of specific aspects of an object (e.g., form, shape, colour)

176
Q

Ventral stream (what) contributions to visual system?

A

Inferior temporal lobe

Conscious perception of specific aspects of an object (e.g., form, shape, colour)

177
Q

Evidence for the existence of these two visual streams comes from studies using the?

A

Ebbinghaus illusion

178
Q

What is the Ebbinghaus illusion?

A

Individuals presented with two discs that are the same size, but appear to be different sizes

When asked to estimate the size of each disc (ventral/perception stream) using their thumb and finger, individuals estimate the discs to be different sizes (INCORRECT)

When asked to reach out and grasp each disc (dorsal/action stream), individuals appropriately scale their grip aperture to the size of the discs (CORRECT)

179
Q

Evidence that posterior parietal lobe is also involved with?

A

Planning and control of eye movements toward an object

Planning and control of arm and hand movements toward an object

180
Q

Lesions involving the posterior parietal lobe may impact an individual’s ability to?

A

Locate and/or track an object

Use spatial information about an object (i.e., size, shape, orientation) to appropriately control the arm movement and hand positioning during reach and grasp tasks

181
Q

Primate (deafferentated) and human (severe peripheral neuropathy) studies suggest that somatosensory input is not required to?

A

produce reasonably accurate simple (i.e., single joint) reaching movements

182
Q

Somatosensory input plays an important role in

A

The production of complex (i.e., multiple joints) reaching movements

The adaptive (feedback) control of grip force during grasping movements – i.e., mismatch between the expected and actual properties of an object (e.g., heavier than expected, more slippery than expected)

Real life example – adapting when something starts to slip out of your hand

183
Q

Somatosensory input plays an important role in

A

The production of complex (i.e., multiple joints) reaching movements

The adaptive (feedback) control of grip force during grasping movements – i.e., mismatch between the expected and actual properties of an object (e.g., heavier than expected, more slippery than expected)

Real life example – adapting when something starts to slip out of your hand

184
Q

Control mechanisms depend on the nature of the task, what are the 2 components involved in this?

A

Pointing task
Reach and grasp task

185
Q

What body parts are involved in the pointing task?

A

the arm, forearm, and hand are controlled as a single unit

186
Q

What body parts are involved in the reach and grasp task?

A

: the arm and forearm are controlled as a single unit (i.e. “reach”), while the hand is controlled separately (i.e., “grasp”)

187
Q

Although reach and grasp components occur together (i.e., hand is shaped to grasp object while you reach), they are controlled by different brain areas which are?

A

Reach – brainstem nuclei, indirect descending pathways

Grasp – motor cortex, direct descending pathways

188
Q

Although reach and grasp components occur together (i.e., hand is shaped to grasp object while you reach), they are controlled by different brain areas which are?

A

Reach – brainstem nuclei, indirect descending pathways

Grasp – motor cortex, direct descending pathways

189
Q

Cerebellum has roles in controlling other aspects of reach and grasp task performance, what are they?

A

Anticipatory (feedforward) postural control strategies that accompany upper limb movement

Control of hand positioning during grasping tasks (especially precision grip)

Anticipatory (feedforward) and reactive (feedback) control of grip force during grasping tasks

190
Q

It has been suggested that the CNS plans and controls upper limb movements by?

A

Using end-point coordinates to plan a movement trajectory

Controlling position of hand relative to movement trajectory

Evidence: People tend to move in straight lines with similar velocity profiles

191
Q

What do Distance programming theories suggest?

A

the CNS programs movements based on muscle activation required to move the required distance

192
Q

Movement speed affects the resulting control strategy used are?

A

Fast movements – correction based on visual feedback not possible (<190 ms); control is solely via initial movement (agonist muscles)

Slow movements – correction based on visual feedback is possible (>260 ms); control is via corrective movements (agonist and antagonist muscles)

193
Q

What do Location programming theories suggest?

A

the CNS programs to achieve a predetermined relative level of tension/stiffness between agonist and antagonist (i.e., every location corresponds to a unique balance of tension/stiffness between opposing muscles

Joints like a door on a spring – relative tension portions of the spring determines door position (muscles = springs; door = limb)

194
Q

Evidence for location programming includes?

A

deafferented primates and humans with somatosensory loss pointed to targets without visual feedback

Accuracy for trials with and without hand perturbations applied were similar

If distance-programming was used, accuracy during the perturbation trials would have been worse since movement programming would have been based on the perceived distance to move the hand

195
Q

Practical considerations – Control theories of reach and grasp (lots of info)?

A

It is likely that both distance and location programming are used to guide upper limb movements, with the strategy used dependent on the task and environmental context

196
Q

Incorporate different types of movements into reach and grasp training such as?

A

Fast movements of varying amplitude to improve accuracy of initial, feedforward movements

Slow movements with visual feedback to improve accuracy of corrective, feedback movements

197
Q

When reaching to point, people generally have a _______ period of deceleration compared to when reaching to grasp an object?

A

Shorter

198
Q

Visual _______ refers to the inability to detect stimuli in both the right and left visual field at the same time?

A

Extinction

KIN 380 (3 decks)

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