week 13- 1 Flashcards

1
Q

biomechanical factors to increase stability

A
  • increase the area of the base of support
  • increased distance from the line of COG
  • decrease of COM over base of support
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2
Q

during quiet standing

A

maintain antigravity posture

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3
Q

during unexpected perturbation

A

reactive balance

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4
Q

during voluntary self-initiated movement

A

anticipatory postural control

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5
Q

reactive balance

A
  • postural control system come into play in response to a destabilizing external force or perturbation
    -utilizes feedback mechanism where the central nervous system responds to info received during and after a movements and attempt to restore stability
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6
Q

muscle synergy

A

particular muscles work together (in synergy) to achieve the task; in the case of reactive balance, it occurs without voluntary control
- muscles involved in the synergy depend on the requirement of the task

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7
Q

ankle strategy

A

involves distal to the proximal sequence of muscles activation
- rotate about ankle only- body stays straight

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8
Q

hip strategy

A

involves proximal to distal activation
- rotate about hip only - legs and torso stay straight

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9
Q

suspensory strategy

A

crouch down- mostly observed on young children (reflective)

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10
Q

step strategy

A

take a step because move outside the limits of stability

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11
Q

reactive balance context dependent

A
  • small balance perturbations usually result in the use of an ankle strategy
  • as perturbation gets larger, there is a switch to hip strategy and finally stepping strategy
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12
Q

if the support surface is changed to a narrow beam

A

use hip strategy at a smaller perturbation magnitude

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13
Q

aging associated with

A

reduced muscle strength and sensory function
-increased postural sway
—– particularly in fallers

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14
Q

response to perturbation are slower with _____ muscle activity

A

greater

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15
Q

hypermetria

A

condition of the dysfunction in which voluntary muscular movements tend to result in the movement of bodily parts (as the arm and hand) beyond the intended goal

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16
Q

sensory contribution to postural control

A

effective postural control requires more than the ability to generate and apply forces and activate appropriate musculature

17
Q

to know when and how to apply forces or to activate appropriate muscles
the

A

CNS must have an accurate picture of where the body is in space and what forces are acting on it

18
Q

3 primary sources of peripheral input (to detect body position and movement relative to space and the environment

A
  1. visual system
  2. vestibular system
  3. somatosensory/ proprioception
19
Q

The contribution of each sensory system is typically assessed by

A
  1. removing or altering/ distorting the sensory information available
  2. using patients population where it is absent or distorted
20
Q

Typically assess the involvement in different settings/contexts. Two common methods

A

(1) Quiet standing (COM or COP)
(2) External perturbations – Re-active

21
Q

vision

A
  • no visual input postural sway increases between 30-40%
22
Q

Physical Perturbation

A

With eyes closed COM displacement is greater following linear translation of support surface beneath feet

23
Q

Visual Perturbation

A

Linear vection. E.g., Sitting in a car, car next to you starts to move, and you perceive that your car is actually moving

24
Q

moving room

A

optic flow important
moving line creates the illusion that person is moving forward shift COM backwards

25
Q

is vision involved in quiet standing

A

yes

26
Q

how do we know

A

Remove vision, greater sway, as indicated by greater movement of the COP/COM
Alter optic flow to give the illusion that a person is swaying in one direction, they
will move the COM in the opposite direction