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Basics of Balance
basics of balance outline
Question | Answer |
---|---|
The maintenance of the COG over the BOS in a given sensory environment | Balance Stability |
Balance Stability + Gaze Stability = ? | Postural Control |
3 pathways of organization | Sensory Input, Central Processing, Motor Output |
3 sensory modalities | Vision, Vestibular, Somatosensory |
3 levels of motor control | Reflexes, Automatic, Voluntary |
3 postural strategies | Ankle, Hip, Stepping |
Dominant sensory input under normal conditions; includes joint & muscle proprioceptors, touch & pressure receptors; Receptors give CNS info about body's position in space | Somatosensory modality |
Plays a significant role when somatosensory is inaccurate; Gives reference of verticality & information about motion of the head | Vision Modality |
Minor role when we have useful somatosensory & visual inputs but it is critical when somatosensory or visual are misleading or unavailable | Vestibular Modality |
Sensory Weighting on a Stable Surface | 70% Somatosensory; 20% Vestibular; 10% Vision |
Sensory Weighting on an Unstable Surface | 60% Vestibular; 30% Vision; 10% Somatosensory |
Muscle spindles improve stiffness properties of the muscle, controlling the effects of external disturbances | Stretch Reflex |
Triggered by external stimuli, occur at fixed latencies, relatively stereotypical & coordinated actions of multiple muscle groups. Amplitude & pattern adapt to task (hip, ankle, stepping strategies) | Automatic Postural Movements |
Which system of movement control can occur in the presence or absence of external stimuli | Voluntary Postural Movement |
Which strategy shifts the COM by rotating the body as a rigid mass from the ankle joints? Mm activity begins in the distal muscle (ant. tib, then quad, then abs); Used when on stable/firm surface & with small perturbations | Ankle Strategy |
Which strategy controls mvmt of COM by flexing & extending the hips; Used when ankles can't exert appropriate torque; Mm activation occurs proximal to distal; Used on small/unstable surfaces with larger & faster perturbations | Hip Strategy |
Which strategy is used when COM is displaced outside BOS? Used in response to fast, large postural perturbations; Vestibular dysfunction can influence which strategy is used | Stepping Strategy |
What is the furthest distance in any direction a person can lean away from midline without altering the BOS? | Limits of Stability |
Normal AP sway in adults is ___ degrees from posterior to anterior | 12.5 degrees; 8 forward & 4.5 backward |
Normal lateral sway | 16 degrees |
Balance Dysfunction | Usually never just 1 cause; May be a major cause with several minor causes; Can be accumulation of multiple minor causes |
Causes of balance dysfunction | Weakness, sensory loss or decrease, loss of joint mobility, central processing problems |