Motor Control of Balance (Part 1)

Question 1

Impact of Disequilibrium

Answer 1

Moves balance from subconscious to conscious activity
Reduces mobility and motor skills
Affects ability to concentrate on other tasks
Creates uneasiness, motion sickness, and vertigo

Question 2

Postural Control

Answer 2

dynamic process by which the body’s position is maintained in equilibrium

Question 3

equilibrium

Answer 3

ability to control center of mass over base of support in a given sensory environment

Question 4

Multisensory integration systems used for balance

Answer 4

vestibular
visual
somatosensory

Question 5

sensory reweighting

Answer 5

ability to adjust the relative contributions of the multisensory systems that are available to maintain postural balance depending on current environmental conditions

Question 6

Diabetes mellitus impact on multi-sensory integration:

Answer 6

Nerve signals are impacted by blood sugar levels

Question 7

Multisensory integration

With no sensory conflicts:

Answer 7

inputs from sensory systems are available and congruent

Question 8

In sensory conflict situations:

Answer 8

CNS is selective

Question 9

How do we assess sense of postural control?

Answer 9

• Sensory organization test (SOT)
• Clinical Test for Sensory Interaction in Balance (CTSIB)

Question 10

Postural control emerges from interaction of which 3 factors?

Answer 10

• Task
• Individual
• Environment

Question 11

What happens as the difficulty of dual tasking increases?

Answer 11

• Dual task becomes more difficult
• More cognitive processing is required
• Secondary tasks influence posture differently

Question 12

Hedman model of control & its components

Answer 12

used to monitor postural control (mostly in neuro conditions)
* initial condition
* preparation
* initiation
* execution
* termination

Question 13

Initial Condition

Answer 13

state of individual’s system and the prevailing environmental conditions
(posture, interactions w/ environment)

Question 14

Preparation

Answer 14

period of time when the movement is being organized within the CNS

Question 15

Initiation

Answer 15

Instant when displacement of the segment begins
Coordination plays a part in effective movement

Question 16

Execution

Answer 16

period of actual segment movement

Question 17

Termination

Answer 17

instant the movement stops
delayed or ineffective movement if they overshoot it

Question 18

COM

Answer 18

Center of Mass
point at which the body is in perfect equilibrium

Question 19

COP

Answer 19

Center of Pressure
location of the vertical projection of the GRF

Question 20

BOS

Answer 20

Base of Support
the perimeter of the contact area between the body and its support surfaces

Question 21

LOS

Answer 21

Limits of stability
the sway boundaries in which an individual can maintain an equilibrium without changing his or her BOS

Question 22

Balance control requires interaction of:

Answer 22

• nervous system
• musculoskeletal system
• contextual effects

Question 23

Balance control systems

Musculoskeletal System factors that impact balance

Answer 23

• Muscle performance
• Joint integrity
• ROM
• Flexibility
• Postural alignment
• Sensation

Question 24

Balance control systems

Nervous System factors that impact balance

Answer 24

• Sensory processing
• Sensorimotor integration
• Motor strategies
• Adaptive mechanisms
• Anticipatory mechanisms

Question 25

# Balance control systems Contextual effect factors that impact balance

Answer 25

* Environment * Support surface * Gravity * Lighting * Task characteristics

Question 26

Types of postural control tasks

Answer 26

steady state reactive (feedback) proactive/anticipatory (feedforward)

Question 27

# Postural control tasks Steady state

Answer 27

maintain position | quiet stance

Question 28

# Postural control tasks reactive (feedback)

Answer 28

response to external forces | pertubed stance

Question 29

# Postural control tasks Proactive/anticipatory (feedforward)

Answer 29

postural adjustments prior to movement | early detection of obstacles

Question 30

Motor strategies for balance control depend on:

Answer 30

speed, intensity of perturbation subject's awareness, posture, and prior experience support surface

Question 31

# Describe activation, plane, pertubation, & surface Ankle strategy

Answer 31

muscle activation distal to proximal slow/small perturbation A-P plane hard surface

Question 32

Muscle activation order during forward sway ankle strategy

Answer 32

Gastroc, ->hamstring ->, paraspinal

Question 33

Muscle activation order during backward sway ankle strategy

Answer 33

Tibialis anterior first, followed by quadriceps then abdomen

Question 34

Hip strategy

Answer 34

muscle activation proximal to distal large perturbation compliant surface narrow stance

Question 35

Muscle activation order during forward sway hip strategy

Answer 35

Abdominals first, followed by the quadriceps

Question 36

Muscle activation order during backward sway of hip strategy

Answer 36

Paraspinal first, followed by hamstrings

Question 37

Stepping strategy

Answer 37

used to prevent a fall and when perturbations are fast/large or when other strategies fail occurs in direction of perturbation

Question 38

Weight-shift strategy

Answer 38

used for ML perturbations

Question 39

Suspensory (suspension) strategy

Answer 39

quickly lowers the body COM by flexing the knees

Question 40

How hot is brad?

Answer 40

Like, really hot

Question 41

What combined strategy is often used by elderly people who are at high fall risk?

Answer 41

stepping and hip strategy>ankle strategy

Question 42

3 movement systems for balance control following perturbation:

Answer 42

Reflexes Automatic Postural response Volitional Postural response

Question 43

Which system has the fastest response time?

Answer 43

reflex <70ms

Question 44

# Movement systems for balance control following perturbations Reflexes

Answer 44

controlled by spinal cord fastest response time independent of task demands produce stereotyped ms. contractions in response to sensory stimulus

Question 45

# Movement systems for balance control following perturbations Automatic Postural Response

Answer 45

controlled by brain stem and subcortical structure functionally organized, long loop responses elicited by external stimuli involuntary limited modification stereotyped response pattern

Question 46

# Movement systems for balance control following perturbations Automatic Postural Responses are coordinated from which ms?

Answer 46

leg and trunk ms activate to bring body's COM into equilibrium

Question 47

# Movement systems for balance control following perturbations Response time of automatic postural responses

Answer 47

intermediate 80-120 msec regardless of task complexity & experience

Question 48

# Movement systems for balance control following perturbations volitional postural responses

Answer 48

controlled by cerebral cortex voluntary control, relating specifically to controlling COM over BOS self initiated or following external stimulus pattern strongly modified by prior experience continuum of possible mvmt patterns

Question 49

# Movement systems for balance control following perturbations volitional postural responses response time

Answer 49

slower, >150 msec relative to task complexity & experience

Question 50

Balance Evaluation Components

Answer 50

* Reflective functional capabilties and quality of postural strategies * Sensitive * Reliable and valid * Practical

Question 51

Balance Evaluation Grades & Descriptive measures

Answer 51

Normal, Good, Fair, Poor, Absent & sitting vs standing static vs dynamic

Question 52

# Documenting Functional Balance (Table 6.6) Normal Balance

Answer 52

Patient is able to maintain steady balance w/o support (static) Patient accepts maximal challenge and can shift weight easily within full range of LOS in all directions (dynamic)

Question 53

# Documenting Functional Balance (Table 6.6) Good Balance

Answer 53

Patient able to maintain balance without handhold support, limited postural sway (static) Patient accepts moderate challenge; able to maintain balance while picking up object off floor (dynamic)

Question 54

# Documenting Functional Balance (Table 6.6) Fair balance

Answer 54

Patient able to maintain balance with handhold support; may require occasional minimal assistance (static) Patient accepts minimal challenge; able to maintain balance while turning head/trunk (dynamic)

Question 55

# Documenting Functional Balance (Table 6.6) Poor Balance

Answer 55

Patient requires handhold support and moderate to maximal assistance to maintain position (static) Patient unable to accept challenge or move without loss of balance (dynamic)

Question 56

# Documenting Functional Balance (Table 6.6) Absent Balance

Answer 56

Patient unable to maintain balance