Postural Control (9/18a) [Integrative Care]

Question 1

Postural control

Answer 1

Involves controlling the body’s position in space for the dual purpose of stability and orientation

Question 2

Postural orientation (posture)

Answer 2

Ability to maintain an appropriate relationship:

1) Between different body segments (alignment)
2) Between the body and the environment for a task

How your mass is centered over your base of support impacts alignment

Question 3

Postural stability (balance)

Answer 3

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

COM does not necessarily stay within the BOS

Question 4

Base of support (BOS)

Answer 4

the area of the body in contact with the support surface

Question 5

BOS relationship

Answer 5

Wide BOS: more stability

Narrow BOS: less stability

Question 6

Center of mass (COM)

Answer 6

the point at the center of the total body mass

COM is a point in 3-dimensional space, usually around L2 in standing

Question 7

COM relationship

Answer 7

Higher the COM: lesser stability

As COM shifts upward the object/subject becomes more “top-heavy”

Lower the COM: greater stability

Question 8

Maintaining vs Controlling COM

Answer 8

Maintaining - COM always stays within BOS

Controlling - COM can move outside BOS but you don’t lose stability

Question 9

Center of gravity (COG)

Answer 9

vertical projection of the COM

COG is vertical projection of COM on 2-dimensional plane, usually the ground

Question 10

COG relationship

Answer 10

COG is within the BOS: greater stability

COG is outside the BOS: lesser stability

Question 11

Center of pressure (COP)

Answer 11

the center of the distribution of total forces applied to the support surface

Represents the average “location” of the ground reaction force vector but NOT the forces themselves → it is a point on a 2- D plane

Question 12

COP and COM relationship

Answer 12

For static equilibrium- COP must be directly under the COM (perfectly aligned with COG)

Standing isn’t static, so rarely aligned

CNS activates muscles to change the location of COP to align it close to COM

If COM goes well beyond the COP, then BOS is changed to ensure that COP and COM are close

Question 13

Static balance (steady-state balance)

Answer 13

ability to maintain COG within the supporting base while standing or sitting

Question 14

Dynamic balance

Answer 14

maintaining an upright position while COG and base of support are moving and the COG is moving outside of the supporting base

Question 15

Functional balance

Answer 15

ability to perform daily movement tasks requiring balance and involves static and dynamic balance

Question 16

Stability vs Orientation relationship

Answer 16

Requirements depend on task, and one may hav to be compromised (complicated relationship)

Postural orientation affects postural stability

Postural orientation is altered to regain postural stability

Question 17

Stability limits

Answer 17

boundaries of the combined COM velocity and position possible without the need to change the base of support

Question 18

Stability limits result from

Answer 18

the interaction between the position and velocity of COM

Question 19

Feedback control (Compensatory or reactive postural responses)

Answer 19

Sensory feedback from unexpected external perturbations triggers postural responses

Response depends on multiple factors:
Amount of perturbation, Properties of support surface, Speed of perturbation, Pathology, Pain

Can test by pushing patient, taking away sensory systems, etc

Question 20

Feedforward control (Anticipatory postural control)

Answer 20

Postural responses are made prior to voluntary movement that is potentially destabilizing in order to maintain stability during the movement

Can test with sit to stand, stepping on toes, etc