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Ability to execute smooth, accurate, and controlled motor responses.
Coordination
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Control of discrete movements of the extremities.
Nonequilibrium coordination
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Control of multi-joint movements for posture and gait, including the trunk.
Equilibrium coordination
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Coordinated movement requires muscles and joints activated with appropriate _____ & _____.
Timing and Scaling
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Time to initiate movement, time to move, and time to terminate movement.
Timing
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Gradation of forces for a particular task.
Scaling
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Age related changes impacting coordination:
- - Decreased strength
- - Slowed reaction time
- - Decreased flexibility
- - Postural changes
- - Alterations in sensation, perceptual skills, and visual & hearing acuity.
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Cerebellar impairments impacting coordination:
Hypotonia, Dysmetria, Dysdiadochokinesis, Tremor, Dyssynergia, Ataxia, Dysarthria, Asthenia, Rebound phenomenon, Nystagmus
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Basal ganglia impairments impacting coordination:
Bradykinesia, Akinesia, Rigidity, Tremor, Chorea, Athetosis, Choreoathetosis, Hemiballismus, Dystonia
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Dorsal column impairments compacting coordination
- - Decreased proprioception
- - Decreased kinesthesia
- - Decreased discriminative touch
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Timing and grading of muscles of the trunk and LE's to maintain an upright position with the COG over the BOS in a given sensory environment.
Equilibrium Coordination
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Environmental conditions, real or imagined, that provide sensory information; the context in which an action occurs.
Sensory environment
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State of remaining fixed or steady against the force of gravity.
Stability
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Body is at rest while maintaining a position.
Static balance
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Body or parts of the body are moving while repeatedly realingning the COG over the BOS.
Dynamic balance
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Greatest distance in any direction that a person can sway or will sway without altering the original base of support or losing balance.
Limits of stability (LOS)
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An automatic response of muscles to changes in COG.
Muscles act in synergy thereby freeing higher brain levels from attending to aspects of maintaining balance.
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Postural adjustments made in preparation for voluntary movement (feedforward).
Anticipatory of proactive
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Automatic responses to disruptions of stability from a specific stimulus (feedback).
Compensatory or reactive.
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Components of Balance:
- 1. Biomechanical / musculoskeletal
- 2. Coordinated normal motor strategies
- 3. Sensory organization
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5 main areas of movement capabilities:
- 1. Alternate or reciprocal motion
- 2. Movement composition
- 3. Movement accuracy
- 4. Fixation of limb holding
- 5. Equilibrium
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Compensatory motor strategies used to maintain balance:
- 1. Ankle strategy
- 2. Weight-shift strategy
- 3. Hip strategy
- 4. Stepping or grasping strategies
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- Delayed onset of muscle action
- Co-contraction of muscles resulting in stiffness
Examples of what?
Timing problems
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Ability to reverse movement between opposing muscle groups.
Alternating or reciprocal motion
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Muscles working together.
Movement composition or synergy
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Ability to gauge and judge speed and distance.
Movement accuracy
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Maintain control in response to alterations in COG or BOS.
Equilibrium or postural stability
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Muscles feel soft, little resistance.
Hypotonia
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Inability to judge distance or range of movement.
Dysmetria
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Impaired ability to perform rapid alternating movements.
Dysdiadochokinesis
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- Movement decomposition
- Movement performed in a sequence of component parts.
- Asynergia
Dyssynergia
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Loss of coordination in gait, posture, and movement pattern with diffficulty in initiating, rate, rhythm, and sequencing.
Ataxia
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- Disorder of motor component.
- Scanning speech characteristic of cerebellar involvement: slow with prolonged syllables and inappropriate pauses.
Dysarthria
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Generalized muscle weakness.
Asthenia
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Inability to stop motion following an isometric contraction.
Rebound phenomenon
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Rhythmic, oscillatory back and forth movement of the eyes.
Nystagmus
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Decreased amplitude and velocity of movement.
Bradykinesia
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Inability to initiate movement.
Akinesia
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Seen at rest; decreases with purposeful movement; increased with stress.
Resting tremor
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Involuntary, rapid, irregular, jerky movements.
Chorea
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Slow, involuntary, twisting movements; "wormlike"
Athetosis
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Large, sudden, flailing movements.
Hemiballismus
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Involuntary sustained muscle contractions.
Dystonia
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Cone of stability:
- 12 degrees A-P
- 16 degrees M-L
- (Normal stance width of 4 inches)
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Primary sensory systems used for sensory organization:
- Somatosensory
- Visual
- Vestibular
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Detractors from balance:
- Cognitive deficits
- Musculoskeletal limitations
- Pain
- Loss of sensory acuity
- Faulty scaling and timing of muscle activation
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For hip strategy, which muscles contract when the body gets perturbed anteriorly?
Abdomen and quads
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For hip strategy, which muscles contract when the body gets perturbed posteriorly?
Erector spinae and hamstrings
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- Small perturbations well within the LOS
- Muscle activation distal to proximal
Ankle strategy
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- Pelvis is the key point of control
- COM moves in frontal plane primarily with hip abductor and adductor muscles
Weight-Shift strategy
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- Response to rapid and/or large external perturbations or on marrow BOS
- COG near LOS
- Muscle activation proximal to distal
- Results in realigning pelvis over the BOS
Hip strategy
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- Large, fast perturbations
- Often used before the others or in combination with other strategies
Stepping or grasping strategies
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Lowering BOS in an unstable surface (ice)
Suspensory strategy
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