Chapter 7

Question 1

What is the clinical definition of a fall?

Answer 1

An even that results in a person coming to rest inadvertently on the ground (unplanned or unexpected)

Question 2

What is the research definition of a fall?

Answer 2

Movement of the COM outside of the BOS

Question 3

What are the 6 main strategies to maintain balance?

Answer 3

1) Controlling body sway
2) Feedback control
3) Feedforward control
4) Anteroposterior stability
5) Lateral stability
6) Multidirectional stability

Question 4

How does our body control body sway?

Answer 4

The COP works to control the COM moving the body backward and forward

Question 5

What is feedback control?

Answer 5

Postural control that occurs in response to sensory feedback from an unexpected perturbation

Question 6

What is feedforward control?

Answer 6

Postural responses made in anticipation of a voluntary movement potentially destabilizing in order to maintain stability during movement

Question 7

What is a synergy?

Answer 7

Functional coupling of groups of muscles that are constrained to act together as a unit

Question 8

What muscles contract during ankle strategy?

Answer 8

Forward = POST (paraspinals, hamstrings, gastroc)
Backward = ANT (abdominals, quads, tibialis anterior)

Question 9

What order do the muscles activate during ankle strategy?

Answer 9

Distal to proximal

Question 10

When is ankle strategy useful?

Answer 10

In small perturbations

Question 11

What muscles contract during hip strategy?

Answer 11

Forward = large ANT (abdominals, quads)
Backward = large POST (paraspinals, hamstrings)

Question 12

What order do the muscles activate during hip strategy?

Answer 12

Proximal to distal

Question 13

When is hip strategy useful?

Answer 13

Large, fast disturbances

Question 14

What 3 strategies are included within anteroposterior stability?

Answer 14

Ankle strategy
Hip strategy
Stepping strategy

Question 15

What occurs during stepping strategy?

Answer 15

When ankle and hip strategies aren’t enough to maintain balance, a step will restore COM

Question 16

T/F Hip and ankle strategies cannot be combined.

Answer 16

False, they are combined in a continuous way

Question 17

What is lateral stability?

Answer 17

An alternative strategy to recover stability in the ML direction

Question 18

What muscles are used in lateral stability, and in what order?

Answer 18

Muscles at the hip and trunk

Proximal to distal

Question 19

What is multidirectional stability?

Answer 19

A continuum of response patterns that control stability in the 360 degree continuum of possible perturbation directions

Question 20

T/F Muscles can belong to more than one pattern of movement or synergy in multidirectional stability.

Answer 20

True

Question 21

According the Dynamic Systems Model, what factors make up postural control?

Answer 21

• Musculoskeletal components
• Internal representations
• Adaptive mechanisms
• Anticipatory mechanisms
• Sensory strategies
• Individual sensory systems
• Neuromuscular synergies

Question 22

What is the cerebellum’s role in postural stability?

Answer 22

Controls adaptation, the ability to modify postural muscle amplitude in response to changing tasks and environmental conditions

Question 23

What is the basal ganglia’s role in postural stability?

Answer 23

Controls postural set, the ability to quickly change muscle patterns in response to changing tasks and environmental conditions

Question 24

What is the brainstem’s role in postural stability?

Answer 24

Controls level of postural tone in combination with the cerebellum. Circuits for autonomic postural synergies. Vestibular contributions

Question 25

What occurs in the spinal preparation area?

Answer 25

Ground reaction forces for orientation present, though diminished Tonically active extensor muscle for antigravity support for postural orientation No lateral stability Somatosensory contributions

Question 26

Why are perceptual systems needed in postural control?

Answer 26

In order for the body to know when and how to apply restoring forces, the CNS must have an accurate picture of where the body is in space and whether the body is stationary or in motion.

Question 27

What are the 3 sensory inputs that contribute to postural control?

Answer 27

Visual Somatosensory Vestibular

Question 28

Why are visual inputs necessary?

Answer 28

The give the relationship of our body to objects in the environment

Question 29

What do visual inputs help position?

Answer 29

Position and move the head with respect to the surrounding objects (direction and speed)

Question 30

Why are somatosensory inputs important?

Answer 30

The provide a surface of support

Question 31

What do somatosensory inputs help to position?

Answer 31

Position and movement about the body with reference to BOS, relationship of body segments to one another

Question 32

Why are vestibublar inputs important?

Answer 32

They help provide a sense of gravity

Question 33

What do vestibular inputs help to position?

Answer 33

Postion and movement of the head with respect to gravity and inertial forces (angular acceleration)

Question 34

What happens when one of the sensory systems is less reliable?

Answer 34

Input to the CNS from the system is weighted less heavily, and inputs from other systems are weighed more heavily

Question 35

Alignment

Answer 35

Relationship of body segments to one another, as well as to the position of the body with reference to gravity and the base of support

Question 36

COM

Answer 36

Point at center of total body mass

Question 37

COG

Answer 37

Vertical projection of the center of mass

Question 38

COP

Answer 38

Center of distribution of total force applied to supporting surface

Question 39

Posture

Answer 39

the biomechanical alignment of the body and the orientation of the body in the environment.

Question 40

Postural Control

Answer 40

Control of the body’s position in space for orientation and stability

Question 41

Postural Tone

Answer 41

Activity increases in antigravity muscle, which keeps the body from collapsing in response to the pull of gravity during quiet stance.

Question 42

Postural Orientation

Answer 42

Ability to maintain an appropriate relationship between body segments, and between the body and the environment for a specific task  

Question 43

Postural Stability/Balance

Answer 43

Ability to control the center of mass in relationship to the base of support