Balance Flashcards
Define center of mass
point in body where mass is distributed equally in all directions; gravity-ind; changes w/ position
define center of gravity (for location , think plum line)
vertical projection of COM, gravity-dependent
define base of support
area that encompasses every point of contact that a person makes with the surface
define postural control
ability to control CoG over BoS
define postural stability
maintaining CoG over BoS under different sensory circumstances
define postural orientation
orientation of the body in response to gravitational demands
How can we define balance is it relates to postural control, stability and orientation?
it is the control of the CoM over the BoS
What major systems are involved in the sensorimotor integration involved with balance?
vision
somatosensory
vestibular
How does our somatosensory system support our balance
dominant for upright ctrl
provides info about muscle length, stretch, tension/contraction, pressure and joint position
How does our visual system support our balance?
central: orientation, object motion, more conscious recognition, ID hazards and opps
peripheral: self in relation to the environment, largely subconscious
FEEDFORWARD PC in changing environment
How does our vestibular system support our balance?
info> CNS re: position/ motion of head via VOR,VSR, VCR
self motion vs environmental motion
How does our central nervous system integrate multisensory information to allow for us to stay balanced
Compares, combines, weighs and reweighs input for the circumstances
What has been found to be the distribution of visual, somatosensory and vestibular input when we are on firm versus compliant surfaces?
Firm: 70% S, 20%Vest, 10% Visual
Compliant: 60% Vest, 30%Visual, 10% S
Define steady state
without challenge to balance (either statically or dynamically )
Where do we see the movements occurring when our body
demonstrates postural sway
sitting (quiet and unsupported): hips
standing (quiet): ankles
define postural sway
normal , gentle, automatic and involuntary A&P oscillations
Define limits of stability. What is normal?
when CoM approaches the limits of the BoS during postural sway or leaning but doesn’t actually move the BoS–normal is 8 degrees in all directions
Define anticipatory control. What mechanisms are behind our ability to successfully execute this?
voluntary, goal-oriented movements in prep for movement
via feedforward system and cerebellar ocntrol
What UE muscles are most commonly involved with anticipatory control tasks? LE?
biceps; gastroc
Define reactive postural responses. What mechanisms are behind our ability to successfully execute this?
reactions to unplanned perturbations. they are triggered by fast and highly myelinated sensory and motor tracts
What are the 3 major reactive strategies we rely on to maintain balance after a perturbation? Is there a particular order to these strategies
ankle>hip>step (should occur 85-90 ms after perceived instability)
explain the different strategies required to maintain sitting versus standing balance
sitting: fewer degrees of freedom while sitting, A/P most stable, reach/grab strategy is the go-to
standing: lateral is most stable, ankle>hip>step strategies are go-to
List the intrinsic fall risk factors we discussed in class
age, impaired balance, prior history of falls, fear of falling, comorbidities, medication side effects
List the extrinsic fall risk factors we discussed in class
type of surface, obstacles, lighting, footwear, poorly fitted assistive devices, recreational drugs, alcohol
