Balance

Question 1

Center of Mass def and location

Answer 1

Point at which distribution of mass is equal in all directions

Slightly anterior to the sacrum

Question 2

What is the difference between CoM and CoG

Answer 2

Com is gravity independent

Question 3

Def and location of CoG

Answer 3

Vertical projection of CoM

Anterior to ankle and knee, posterior to hip, trunk midline, anterior to GH jt, and through external auditory meatus

Question 4

What is the BOS

Answer 4

Area beneath a person that includes every point of contact that a person makes with the supporting surface

Question 5

Balance def

Answer 5

Control of com over bos

Question 6

Postural control v postural stability v postural orientation

Answer 6

Static v dynamic v gravitational demands impacting body position

Question 7

Balance is the result of CNS processing of what 3 systems

Answer 7

Somatosensory, vestibular, and vision

Question 8

Sensorimotor input of balance

Answer 8

Mechano and proprioceptors provide info about muscle length, stretch, tensio, and contraction as well as pressure and jt position

Dominant sense for upright postural control (starts at feet)

Question 9

Visual input for balance is a combination of what 2 types of vision

Answer 9

Central (foveal) vision

Peripheral (ambient) vision

Question 10

What is the central (foveal) vision responsible for

Answer 10

Environmental orientation
Contributes to perception of verticality and object motion
Identify hazards and opportunities

Question 11

Which type of vision receives more conscious recognition than peripheral vision

Answer 11

Central/foveal

Question 12

What is the function of peripheral vision

Answer 12

Detects motion of self in relation to environment (head movements, postural sway)
Largely subconscious

Question 13

What type of postural control comes from a change in environment

Answer 13

Feedforward/ anticipatory

Question 14

Vestibular input on balance

Answer 14

Provides information to cns about position and motion of the head via semicircular canals and otoliths (VOR VSR VCR)

Question 15

How is the vestibular system unique in how it contributes to balance

Answer 15

It can distinguish self motion from environmental motion

Question 16

CNS processes the available sensory by these receptors in varying degrees by….

Answer 16

Comparing available inputs
Combining inputs
And weighing and redesigning input for all circumstances

Question 17

When on a firm surface, postural control is achieved from what ratio of sensory input

Answer 17

70 somatosensory
20 vestibular
10 vision

Question 18

On a compliant surface, postural control is achieved by what ratio of sensory input

Answer 18

60 vestibular
30 visual
10 somatosensory

Question 19

When changes in the environment occur, the relative ________, _____________, and _________ of information from the sensory systems may also

Answer 19

Availability, accuracy, and usefulness

Question 20

When reweighing sensory info, available, accurate, and useful info is _________ and unavailable, inaccurate, or less useful info is _________

Answer 20

Unweighted

Downweighted

Question 21

Any neurological injury to the vestibular, somatosensory, or visual systems will also impact

Answer 21

Balance/ postural stability/control/orientation

Question 22

Sensory input is processed by cns to allow for descending commands to _______ and ____________ systems to allow for our body to be in one of 3 states…

Answer 22

Motor
Neuromuscular

Steady state, anticipatory control, reactive control

Question 23

Postural sway

Answer 23

Normal, gentle, and involuntary A&P oscillations

Question 24

Limits of stability

Answer 24

Points at which CoM approaches the limits of the BOS during postural sway or learning

8º in all directions

Question 25

Describe Anticipatory postural control

Answer 25

Voluntary, goal-directed movements in preparation for movement

Question 26

Anticipatory postural control involves motor planning based on ______________ to avoid loss of balance. Making this a ____________system

Answer 26

Past experience

Feedforward

Question 27

Anticipatory postural control has some _________ control

Answer 27

Cerebellar

Question 28

What are the most common muscles involved in anticipatory control

Answer 28

UE: bicep
LE: gastroc

Question 29

Reactive postural control def

Answer 29

Reaction to unplanned perturbations to balance resulting in displacement of CoG or moving the BOS

Question 30

Reactive postural control is a feedback system dependent on

Answer 30

Fast sensory and motor neurons (heavily myelinated type 1(a) fibers)

Question 31

What are the 3 reactive strategies and when are they used

Answer 31

Ankle- quiet standing or small perturbations
Hip- large perturbations
Stepping- when other strategies fail

Question 32

What reactive strategy is the primary strategy for mediolateral control

Answer 32

Hip

Question 33

What reactive strategy should ultimately increase the BOS

Answer 33

Stepping strategies

Question 34

Reactive strategies should be ____________ and _________

Answer 34

Automatic and fast

Question 35

(Sitting/standing) balance has more DOF

Answer 35

Standing 6 deg

Sitting 3 deg

Question 36

(Sitting/standing) balance is most stable in the A/P position, causing LOB usually laterally

Answer 36

Sitting

Standing is most stable laterally w lob A/P

Question 37

Anticipatory control in standing balance usually involves what muscles

Answer 37

Gastroc and truck postural muscles

Question 38

Anticipatory control for sitting balance involves what muscles

Answer 38

Gastroc
Quad
Glute