L3 Reflexes Flashcards
Balance, postural stability
maintaining stability in an upright posture to keep the body up against gravity
Center of mass
single point at which the entire mass of an object lies
Base of support
all points of body contact with supporting surface
described, visualized as area enclosed within the perimeter of all points of contact
Limits of stability
maximum distance a person can intentionally move or displace thier COM in each direction without losing balance
Postural REsponses
developed during childhood, these reflexive/stereotypical response occur to certain sensory stimuli
Righting reactions
Orient head in space, orient body in relation to head and the support surface.
Occur in response to visual, vestibular, somatosensory cues
Somatosensory cues
body on head righting
Protective Reactions
Prevent fall after COM moves beyond LOS
Reach to prop on surface by one or more extremity to prevent injuries, avoid falls, reset BOS
develops 6-9 months anteriorly, 10-12 months posteriorly
Equilibrium Reactions
-integration of righting and protective reactions
-multidirectional responses to intrinsic/extrinsic forces
-involves trunk rotation in conjunction w/extension and abduction
becomes adaptable at 1 year, declines later in life
Mild perturbation causes…
righting reaction
Moderate perturbation causes
equilibrium reaction
Strong perturbation causes
protective responses
Ankle Strategy
utilized with subtle balance responses to environment
shifts a person’s COM toward center of BOS for increased postural stability
works from distal to proximal
Hip strategy
utilized when greater force reactions needed than ankle strategy to keep from falling
proximal to distal muscle activation
Stepping Strategy
occurs to recover stability when COM becomes suddenly outside of BOS, occurs when ankle/hip strategies don’t work
Afferent sensory system
Vision, Vestibular, Somatosensory
CNS regulates goal-directed postural control and automatic postural responses with integrated info from all three systems
Vision Sensory Input
Environmental info, particularly for orientation
Involved in static and dynamic conditions
Begins in early development
Navigation of obstacles, objects in environment
vision helps with negotiation of movement parameters
Vestibular Sensory Input
-Semicircular canals and otolith organs in the inner ear
-Position of the head relative to gravity
-Stabilization of gaze during head movements
-Regulation of postural tone and muscle activation
-used most when other systems are limited
Somatosensory Sensory Input
-Cutaneous touch, pressure from skin
-proprioceptive, kinesthetic info from muscle spindles, golgi tendon organs, joint capsule receptors
Aging and Sensory Systems
decline in each system
increased difficult for elderly to maintain balance because of decreased sensory input
Posturography
objective data obtained via computerized balance assessment, force platform
examines location of center of pressure, postural sway, limit of stability
Static Posturography
Maintains quiet stance while on force platform
Visual feedback provided via computer monitor to keep cursor within central target box
Dynamic Posturography
standing on force platform, and shifting their COP towards ends of BOS
