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Normal Postural Control
Test 1
70
Physiology
Graduate
07/06/2011

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Term
Emerges from interaction of individual with task and environment
Definition
Postural Control
Term
A complex interaction of musculoskeletal and neural systems
Definition
Postural Control
Term
Controlling body's position in space for stability and orientation
Definition
Postural Control
Term
Ability to maintain an appropriate relationship among body segments, and betweent he body and the environment
Definition
Postural Orientation
Term
Antigravity support is organized at _ level
Definition
Spiral
Term
"balance", ability to maintain body in equilibrium, maintain COM over BOS
Definition
Postural Stability
Term
3 aspects of postural stability
Definition
1. Static equilibrium
2. Dynamic equilibrium
3. Organized at higher levels (brainstem, cerebellum)
Term
Specific orientation and stability requirements vary according to what 2 things?
Definition
Task and environment
Term
Strategies used to accomplish postural control must adapt to varying _ and _ demands
Definition
Task and environmental
Term
Point at the center of the total body mass
Definition
COM (Center of mass)
Term
COM is at what percentage of standing height in males
Definition
57%
Term
COM is at what percentage of standing height in females?
Definition
55%
Term
Center of distribution of total force applied to supporting surface
Definition
COP (center of pressure)
Term
The vertical projection of the center of mass to the ground
Definition
COG (center of gravity)
Term
Relationship between COM, COG, and COP provides better insight into stability than either _, _, or __ alone
Definition
COP
COG
COM
Term
What is the normal anteroposterior sway at quiet stance in young adults?
Definition
5-7 mm
Term
What is the normal mediolateral sway at quiet stance in young adults?
Definition
3-4 mm
Term
Where the trunk sways around the ankle joint like a pendulum.
Definition
Inverted pendulum model
Term
Area within which body can maintain position without changing BOS
Definition
Stability Limits
Term
Change according to characteristics of individual, task, and environment
Definition
Dynamic
Term
Distance a person is willing and able to move without losing balance and stepping
Definition
Perceived stability limits
Term
Varies greatly between individuals; decreases with age in adults
Definition
Perceived stability limits
Term
Interaction between COM position and velocity determine _ vs _
Definition
Stability
Need to step
Term
4 things required by postural control.
Definition
1. Integration of sensory information to assess the position and motion of the body in space.
2. Ability to generate and coordinate forces for conrolling body position.
3. Adaptive postural control
4. Anticipatory postural control
Term
Modify sensory and motor systems in response to changing task and environmental demands
Definition
Adaptive Postural Control
Term
Prepare sensory and motor systems for postural demands based on previous experience and learning.
Definition
Anticipatory Postural Control
Term
What 2 parts of the brain control higher level planning
Definition
Frontal and Motor cortex
Term
What 2 parts of the brain control coordination
Definition
Brainstem
Spinal networks coordinating muscle response synergies
Term
What controls the generation of movement?
Definition
Muscles and motor neurons
Term
Ideal __ allows maintenance of equilibrium with least energy expenditure
Definition
Alignment
Term
Force with which muscle resists lengthening; stiffness
Definition
Muscle Tone
Term
Increased level of activity in certain antigravity muscles throughout the body to counteract gravity in upright positions
Definition
Postural Tone
Term
Name 2 inputs that influence postural tone
Definition
Somatosensory and vestibular inputs
Term
Name 2 postural movement strategies used to maintain equilibrium in dynamic situations.
Definition
1. Reactive (feedback) control (automatic postural response)
2. Proactive (feedforward) control (anticipatory postural adjustments)
Term
In response to external disturbances. During gait and with disruptions to gait cycle.
Definition
Reactive (feedback) control (automatic postural responses)
Term
To prevent disturbance, prior to voluntary movement. During voluntary COM movements in stance.
Definition
Proactive (feedforward) control (anticipatory postural adjustments)
Term
What muscles are activated during forward sway ankle strategy
Definition
Gastrocs
Hamstrings
Paraspinals
Term
What muscles are activated during backward sway ankle strategy
Definition
tibialis anterior
quads
abdominals
Term
This strategy is used most often when on firm surface, with small perturbations
Definition
Ankle strategy
Term
Large, rapid movement at hips, with antiphase (opposite direction) rotation at the ankles
Definition
Hip strategy
Term
What muscles are activated during forward sway hip strategy
Definition
Abs
Quads
Term
What muscles are activated during backward sway hip strategy
Definition
Paraspinals
Hamstrings
Term
Strategy used most often in response to larger, faster perturbations, when on compliant surface, or when surface is smaller than the feet.
Definition
Hip Strategy
Term
When "in place" strategies are insufficient to recover balance, individual takes a step or reaches to realign BOS under COM
Definition
Stepping Strategy
Term
This movement is primarily at the hips, hip muscles are activated before ankle muscles, and smooth matched unloading and loading of LEs
Definition
Mediolateral Stability in Stance
Term
Flexible and alter in a task-dependent manner
Definition
Muscle synergies
Term
-Easily shift from one strategy to another as needed
-Constantly modulate amplitudes of postural responses, according to context
-With repeated exposure, modulate amplitude of response to optimize efficiency
Definition
Adapting motor strategies
Term
Not organized at the spinal level, but is controlled by higher centers, such as the brainstem and cerebellum
Definition
Postural Stability
Term
In order to know when and how to apply restoring forces, the CNS must have an accurate picture of where the body is in space and whether it is what or what?
Definition
Stationary or in motion
Term
3 roles of sensory systems
Definition
1. Pick up info from environment
2. Develop internal representations (central processes)
3. Trigger pro-active (anticipatory) and reactive (automatic) balance responses
Term
3 senses that are typically used for postural control
Definition
1. Visual
2. Somatosensory (Proprioceptive, cutaneous, and joint receptors)
3. Vestibular
Term
Provides information about verticality and motion in the visual field. It is not always necessary and not always an accurate source of information about self-motion vs. object motion
Definition
Visual system
Term
Provides information about body's position in space with reference to support surface, and relationship of body segments to each other
Definition
Somatosensory
Term
Contains muscle spindles, GTOs, joint receptors, cutaneous mechanoreceptors. It is not as useful when the surface is moving relative to body, or when the surface is not horizontal
Definition
Somatosensory
Term
Provides information about position and motion of head with respect to gravity and intertia.
Definition
Vesticular System
Term
It is important in distinguishing object motion vs self motion. Alone, it cannot provide accurate information about how body is moving in space.
Definition
Vestibular system
Term
Name 4 sensory strategies during quiet stance
Definition
1. Proprioception from all parts of the body is used
2. Even light touch (on stable surface) can reduce postural sway
3. Vision not necessary, but does contribute to postural control
4. In general all three senses contribute to postural control in quiet stance
Term
What type of information is fastest during perturbed stance?
Definition
Somatosensory (80-100 msec muscle response latency vs 200 msec for vision_)
Term
Adults and children over 7 years old rely most on what type of information during perturbed stance?
Definition
Somatosensory
Term
Children under 7 rely most on what 2 systems during perturbed stance?
Definition
Somatory sensory or vestibular
Term
Gain or importance of any of the senses depends on its accuracy as a reference for body motion
Definition
Sensory reweighting hypothesis
Term
A response based on anticipation of what is required for task
Definition
CNS preprograms
Term
CNS preprograms are based on what?
Definition
Experience
Term
What muscles are activated before prime movers?
Definition
postural
Term
Name the 2 phases of anticipatory muscle activation
Definition
1. Preparatory phase
2. Compensatory phase
Term
This phase includes postural muscles activated 50 msec in advance
Definition
Preparatory Phase
Term
This phase includes postural muscles activated again after prime movers
Definition
Compensatory Phase
Term
Adapt to conditions of the task. Also adapts to amplitude of response according to size of anticipated disturbance.
Definition
Anticipatory Postural Control
Term
Including a 2nd task increases sway, but decreases sway if visual focus on second task is aided
Definition
Dual-task paradigms
Term
__ effects are small unless postural system is stressed and secondary task is complex
Definition
Attentional
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