Lesson 2: Biomechanics of Postural Control

Question 1

POSTURE

Answer 1

The orientation, or alignment, of the human body, and can be either static or dynamic
● Arrangement of body segments in relation to a task (e.g., upright sitting, slouched sitting, upper extremities oriented forward).
● Position or attitude of body, characteristic matter of bearing one’s body (e.g., slouched/upright walking)
● Through evolution, man became bipedal.

Question 2

IDEAL UPRIGHT POSTURE

Answer 2

Position in which all the body segments are
aligned relatively vertically, and the Line of
Gravity (LoG) passes through or is as close to
the joint axis as possible

Question 3

Postural Control

Answer 3

The act of maintaining balance at rest, during
movement, or with positional changes given
the constraints of the individual, the
environment, or the task

Question 4

Postural Control Involves what?

Answer 4

Orientation / Posture
○ Stability / Balance

Question 5

To have intact postural contact, one should
have good:

Answer 5

Vision Sense
Vestibular Sense
Proprioception
Tactile/cutaneous system

Question 6

ORIENTATION/POSTURE

Answer 6

Ability to maintain an appropriate relationship
between the body and body segments for a
particular task.
○ For example, the optimal posture for
cooking is standing, with the arms
positioned at a 90-degree angle on the
table.

Question 7

STABILITY/BALANCE

Answer 7

Ability to control or maintain the center of
gravity/mass within the base of support
(BOS).
○ The LOG must be located within the
base of support. Thus, in this image,
the LOG is positioned somewhere
between the two feet (BOS)

Question 8

Reactive Postural Control

Answer 8

Happens as a response to external forces
acting on the body.

Question 9

Proactive Postural Control

Answer 9

Happens when the body readies itself in
anticipation of upcoming movements.

Question 10

Adaptive Postural Control

Answer 10

Happens when adaptations occur in the
sensory and motor systems in response to
the task and environmental demands

Question 11

The motion of an upright body characterized
by constant, minute displacements and
corrections to maintain the center of mass
(COM) over the body’s BOS
○ Usually due to breathing, cardiac
movements (heartbeats), blinking, etc.
○ Is most noticeable to an observer
when a person closes their eyes and
attempts to stand completely still.
● The body’s attempt to bring back stability

Answer 11

POSTURAL SWAY

Question 12

Where postural sway primarily occurs at

Answer 12

e ankle-foot segment

Question 13

If a person is standing with a 4-in distance in
between the feet:

Answer 13

○ Sagittal plane: sway can be as large
as 12”
○ Coronal plane: sway can be as large
as 16”