Postural Control Flashcards
postural control
control of body position in space
3 goals of postural control
support body against gravity / external forces
maintain COM over BOS
stabilize some parts of body while others move
limits of stability
perimeter of BOS beyond where we can control
ie. how far COM can be moved over BOS
Centre of pressures
point of ground reaction force vector
Ground reaction force vector
when body contacts ground, ground pushes back on body with equal and opposite magnitude
Centre of Mass
point where equal body mass on all sides
does COM need to be on body
no
Centre of gravity
point where gravity appears to act
base of support
points of contact between body and enviornment
base of support if sitting?
ie. under feet under buttocks etc..
postural sway
small movements of body when unsupported (sitting or standing)
postural sway is NOT normal T/F
false - its normal
What is used to measure postural sway
COM, COP (center of pressure)
Anticipatory postural control enabled by?
feedforward control
feedback control
sensory signals compared with desired state
error = body adjusts
feedback control open or close loop system
closed
feedback forward
predicts disturbances and produces actions to maintain stability
makes “best guess” action
feedback forward open or closed loop system
open
anticipatory postural control
sensory/motor system expectation of postural demands created by internal or anticipated external perturbation
based on learning / exp
examples anticipatory postural control
arms raise while standing, open/pull door, rising on toe etc..
reactive postural control
response to unanticipated external perturbation
Postural response triggered by 3 types of sensory inputs
somatosensory system
vestibular receptors
visual input
function mm spindles
sense length
role golgi tendon
sense force/ strength
parts of somatosensory system
mm proprioceptors, mm spindles, golgi tendons, joint receptors, cutaneous receptors
what do vestibular receptors do
sense sway through head motion
how long does it take somatosensory system to react
60-100 ms
if eyes closed head turned which receptors will be most important
vestibular - but its usually somatosensory otherwise
how long does it take mm reflexes from visual cues to respond
200 ms
name three clinical assessments of balance
berg balance, functional reach, activity specific balance confidence scale (ABC)
What score on berg test makes you a risk for falls
less than 46
berg scale is good for who bad for who
Good for GF strong patient etc.. bad for sport med patient
what score on function reach test is bad
less than 6 or 7 inches means limited functional balance
healthy ppl can hit 10 inches
