Balance

Question 1

Define center of mass

Answer 1

point in body where mass is distributed equally in all directions; gravity-ind; changes w/ position

Question 2

define center of gravity (for location , think plum line)

Answer 2

vertical projection of COM, gravity-dependent

Question 3

define base of support

Answer 3

area that encompasses every point of contact that a person makes with the surface

Question 4

define postural control

Answer 4

ability to control CoG over BoS

Question 5

define postural stability

Answer 5

maintaining CoG over BoS under different sensory circumstances

Question 6

define postural orientation

Answer 6

orientation of the body in response to gravitational demands

Question 7

How can we define balance is it relates to postural control, stability and orientation?

Answer 7

it is the control of the CoM over the BoS

Question 8

What major systems are involved in the sensorimotor integration involved with balance?

Answer 8

vision
somatosensory
vestibular

Question 9

How does our somatosensory system support our balance

Answer 9

dominant for upright ctrl

provides info about muscle length, stretch, tension/contraction, pressure and joint position

Question 10

How does our visual system support our balance?

Answer 10

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

Question 11

How does our vestibular system support our balance?

Answer 11

info> CNS re: position/ motion of head via VOR,VSR, VCR

self motion vs environmental motion

Question 12

How does our central nervous system integrate multisensory information to allow for us to stay balanced

Answer 12

Compares, combines, weighs and reweighs input for the circumstances

Question 13

What has been found to be the distribution of visual, somatosensory and vestibular input when we are on firm versus compliant surfaces?

Answer 13

Firm: 70% S, 20%Vest, 10% Visual
Compliant: 60% Vest, 30%Visual, 10% S

Question 14

Define steady state

Answer 14

without challenge to balance (either statically or dynamically )

Question 15

Where do we see the movements occurring when our body

demonstrates postural sway

Answer 15

sitting (quiet and unsupported): hips

standing (quiet): ankles

Question 16

define postural sway

Answer 16

normal , gentle, automatic and involuntary A&P oscillations

Question 17

Define limits of stability. What is normal?

Answer 17

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

Question 18

Define anticipatory control. What mechanisms are behind our ability to successfully execute this?

Answer 18

voluntary, goal-oriented movements in prep for movement

via feedforward system and cerebellar ocntrol

Question 19

What UE muscles are most commonly involved with anticipatory control tasks? LE?

Answer 19

biceps; gastroc

Question 20

Define reactive postural responses. What mechanisms are behind our ability to successfully execute this?

Answer 20

reactions to unplanned perturbations. they are triggered by fast and highly myelinated sensory and motor tracts

Question 21

What are the 3 major reactive strategies we rely on to maintain balance after a perturbation? Is there a particular order to these strategies

Answer 21

ankle>hip>step (should occur 85-90 ms after perceived instability)

Question 22

explain the different strategies required to maintain sitting versus standing balance

Answer 22

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

Question 23

List the intrinsic fall risk factors we discussed in class

Answer 23

age, impaired balance, prior history of falls, fear of falling, comorbidities, medication side effects

Question 24

List the extrinsic fall risk factors we discussed in class

Answer 24

type of surface, obstacles, lighting, footwear, poorly fitted assistive devices, recreational drugs, alcohol

Question 25

Why is balance a common problem in the geriatric population?

Answer 25

mainly due to vestibular and visual changes

Question 26

what are the major functional implications of vision changes for the geri population?

Answer 26

higher fall risk @ night or in reduced lighting
at risk for tripping due to peripheral loss
slower anticipatory and rxn time> reduced strategies

Question 27

what are the major functional implications of vestibular changes for the geri population?

Answer 27

less detection of rotation and gravity-related positions, reduced gaze stabilization w/ head movement, increased postural sway,

**sensory substitutions can sometimes mask

Question 28

what are the major functional implications of musculoskeletal changes for the geri population?

Answer 28

reduced strength, power, and muscle endurance, prevalence for OP can lead to higher incidence of fall fractures, postural changes>change in CoM/CoG/BoS, greater axial stiffness and reduced flexibility

Question 29

how do we ID “fall risks” ?

Answer 29

observation, clinical history taking, neuro exam, subjective and objective outcome measures