Postural Control Flashcards
What is postural control?
Postural Control: Controlling the body’s position in space for the dual tasks of stability and orientation
What are the two main components of postural control?
(1) Postural stability:
- Ability to control center of mass (COM) inrelationshipto the base of support (BOS )
(2) Postural orientation:
- Ability to maintainanappropriaterelationshipbetweenbody segmentsand betweenthe bodyand the environment foratask
Why is postural control important?
It is critical for independence and safety, and provides efficiency for performing functional tasks such as walking, sit-to-stand, reach and grasp, and sitting.
Which systems interact for postural control?
(1) Sensory/perceptual systems
- Vision
- Vestibular
- Somatosensory
(2) Higher-level CNS processing
- Integrates and makes action plan
(3) Motor systems
- Organize and execute motor movement
What are the sensory/perceptual systems involved in balance?
Vision, vestibular system, and somatosensory system.
What is steady state postural control?
The ability to control the body’s center of mass within the base of support under predictable and non-perturbed conditions.
What factors influence steady state postural control?
- Body alignment/posture
- Muscle intrinsic properties (tone and stiffness)
- Postural tone
- Movement strategies
What is anticipatory postural control?
Anticipatory Postural Control: The ability to generate postural adjustments in the legs and trunk prior to the onset of a voluntary movement.
What is reactive postural control?
Reactive Postural Control: The ability to recover a stable position following an unexpected perturbation.
What are the different motor strategies for balance?
- Ankle strategy
- Hip strategy
- Stepping strategy
- Upper limb reach and grasp
When is the ankle strategy used?
When sway frequencies are low and disturbances of COM are small.
When is the hip strategy used?
For faster sway frequencies, larger disturbances of COM, and when the support surface is small.
- Muscles activated proximal to distal
When is the stepping strategy used?
When displacement is fast and/or large and ankle/hip strategies prove inadequate.
What are the limits of stability?
The maximum distance one can move in any direction without loss of balance or changing the BOS.
What is sensory reweighting?
Sensory Re-weighting: The process where reliance on one sensory system for balance increases while another decreases.
What are common reasons for impaired steady state balance?
Motor impairments, altered alignment, increased postural sway, disrupted sensory reweighting, and reliance on vision.
What are common abnormalities in anticipatory balance?
- Loss of anticipatory processes
- Impaired timing
- Hesitant movement initiation
- Altered direction of movement
What are common abnormalities in reactive balance?
- Sequencing problems
- Delays in muscle activation
- Adaptation problems
- Difficulty scaling postural responses
What are common deficits in steady state balance for patients with neurological impairment?
- Inability to maintain position
- Excessive postural sway
- Reliance on UE support
What are common deficits in anticipatory balance for patients with neurological impairment?
Abnormal BOS, impaired timing, loss of balance, and altered movement direction.
What are common deficits in reactive balance for patients with neurological impairment?
- Excessive sway
- Hesitant reaching
- Ineffective LE stepping
What is postural stability?
Postural Stability: The ability to control center of mass (COM) in relationship to the base of support (BOS).
What is postural orientation?
Postural Orientation: The ability to maintain an appropriate relationship between body segments and between the body and the environment for a task.
What are the three key constructs of balance?
- Steady state postural control
- Anticipatory postural control
- Reactive postural control
What produces steady state postural control?
- Body alignment/posture
- Muscle intrinsic properties
- Postural tone
- Movement strategies
What is body alignment/posture in the context of postural control?
Alignment helps minimize the effects of gravitational forces which pull us off center.
What is intrinsic muscle tone?
Keeps the body from collapsing in response to gravity.
What is postural tone?
Activation of antigravity muscles during quiet stance.
What is the role of movement strategies in postural control?
Postural sway and adjustments made to maintain balance during quiet stance.
What is the role of the CNS in anticipatory postural control?
The CNS ‘pre-tunes’ the system for movement based on previous experience and learning.
What are the motor strategies for reactive postural control?
Activation of multiple muscles in the legs and trunk to recover a stable position of COM relative to the BOS.
