Normal Postural Control

Front 1

List the 2 frameworks in rehabilitation science for posture and balance

Back 1

1. reflex/hierarchical theory
2. systems theory

Front 2

The postural control system is an integrated system of

Back 2

musculoskeletal and neural systems

Front 3

Define the reflex/heirarchial theory of posture/balance

Back 3

- there is an organization of reflex responces from independent sensory systems
- these transition from initial spinal reflexes to higher cortical responses with age

Front 4

Define the systems theory of posture/balance

Back 4

postural control is an interaction of 3 key things:
- individual
- task
- environment
and the sucessful responce depends on an integrated neuromusculoskeletal system

Front 5

What are the two purposes of postural contol?

Back 5

1. stability
2. orientation

Front 6

Define postural control

Back 6

controlling the body's position in space for the dual purposes of stability and orientation

Front 7

Define postural orientation

Back 7

ability to maintain an apropriate relationship between (1) the body segments and (2) the body and the environment

Front 8

3 keys sensory systems for general postural control in functional tasks

Back 8

- vestibular (gravity)
- somatosensory (support surface)
- visual (relation to objects in environment)

Front 9

General body position in most functional tasks

Back 9

vertical (importance of gravity)

Front 10

Define postural stability

Back 10

- balance
- ability to maintain the body in equilibrium

Front 11

List the two types of postural stability

Back 11

- statis (at rest)
- dynamic (in motion)

Front 12

Describe postural stability in the sense of steady state

Back 12

stable system is one whose movement is not significantly altered from a desired trajectory even when it is given perturbations.

Front 13

Most basic stable body configuration

Back 13

center of mass is maintained over base of support

Front 14

How is center of mass determined

Back 14

the weighted average of the center of mass of each body segment

Front 15

What do we call the vertical projection of the center of mass?

Back 15

center of gravity

Front 16

Define center of gravity

Back 16

the vertical projection of the center of mass

Front 17

Define postural stability in terms of center of mass

Back 17

the abiity to mainatin the center of mass within the limits of the base of support

Front 18

In balance, the base of support is also called

Back 18

stability limits

Front 19

Factors affecting dynamic state of stability limits

Back 19

- task
- individual biomecanics
- environment

Front 20

Define the center of pressure

Back 20

The vertical projection of the muscular forces acting on the center of mass

Front 21

What do we call the vertical projection of the muscular forces acting on the center of mass?

Back 21

the center of pressure

Front 22

7 conceptual systems contributing to postural control

Back 22

1. musculoskeletal
2. internal representations
3. adaptive mechanisms
4. anticipatory mechanisms
5. sensory strategies
6. indivual sensory systems
7. neuromuscular synergies

Front 23

Describe perception and action in postural control

Back 23

need to be able to (1) integrate sensory information to assess the position and motion of the body in space and (2) generate forces for controlling body position systems.

Front 24

Define adaptive postural control

Back 24

modifying sensory and motor systems in response to changing task and environmental demands

Front 25

"other" aspects of cognition that affect postural control

Back 25

- attention
- motivation
- intent

Front 26

Define postural motor strategies

Back 26

organization of movements appropriate for controlling the body's position in space

Front 27

When standing what is the primary direction of sway?

Back 27

forward/backward

Front 28

What three factors contribute to our background muscle tone during quiet stance?

Back 28

1. intrinsic stiffness of muscles themselves
2. background muscle tone
3. postural tone (activation of antigravity muscles)

Front 29

2 general categories of factors that contribute to stability in quiet stance

Back 29

1. alignment
2. muscle tone

Front 30

Through what points does the vertical line of gravity fall if there is good alignment during quiet stance?

Back 30

- mastoid
- anterior to shoulder
- at or just post to hip
- anterior to knee
- anterior to ankle

Front 31

List the muscles that are tonically active during the control of quiet stance

Back 31

- erector spinae
- iliopsoas
- gluteus medius
- gastrocnemius
- tensor fascia latae
- soleus
- abdominals (intermittent)
- tibialis anterior (with backwards sway)
- biceps femoris

Front 32

Define muscle tone

Back 32

the force with which a muscle resists being lengthened (its stiffness)

Front 33

General thoughts about cause of resting muscle tone

Back 33

- caused by low levels of free calcium in muscle fiber
- cause low level of continual recycling of cross-bridges
- considered a non-neural mecahnism

Front 34

Important reflexes in postural tone

Back 34

- tonic neck reflex
- vestibulocollic reflex
- vestibulospinal reflex

Front 35

Center of pressure (COP) mobility in person's with Parkinson's

Back 35

decreased

Front 36

Center of pressure (COP) mobility in dancers

Back 36

increased

Front 37

In general, describe the relationship between center of pressure mobility and postural control

Back 37

Generally more mobility (more sway) reflects less control

Front 38

General range of limits of stability in stance

Back 38

- A/P limits: 50-80% of foot length
- Med/lat limits: 60-80% of stance width

Front 39

Describe a synergy in postural control

Back 39

the functional coupling of groups of muscles such that they are considered to act together as a unit

Front 40

List the 3 major strategies for anterior posterior stability in quiet stance

Back 40

1. ankle strategy
2. hip strategy
3. stepping strategy

Front 41

When is the ankle movement strategy typically used and what must be intact?

Back 41

- usually in situations where the perturbation is small and the support surface is firm
- need intact ROM at ankles and good muscle strength

Front 42

Describe the ankle movement strategy to correct for forward sway

Back 42

gastrocnemius, then hamstrings, then paraspinals

Front 43

Describe the ankle movement strategy to correct for backward sway

Back 43

anterior tibialis, then quadriceps then abdominal muscles

Front 44

In general what is the progression of muscle contraction in the ankle movement strategy?

Back 44

muscles activate in order from distal to proximal

Front 45

General description of the hip strategy for controlling body sway

Back 45

produces large and rapid motion at the hip joints with antiphase rotation of the ankles

Front 46

Typical situations in which the hip strategy is used for controlling body sway

Back 46

- faster, larger perturbations
- support surface is complicated or smaller than the feet (like a beam)

Front 47

When is the stepping strategy used for controlling body sway?

Back 47

when in-place strategies (such as ankle and hip) fail