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Flashcards in Week 6 Deck (44)
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1

Define static and dynamic posture.

static - not moving posture

dynamic - moving posture

2

Define base of support and center of gravity/center of mass.

BoS - area bounded posteriorly by tips of heels and anteriorly by tips of toes

CoG - point where mass of body is centered

3

What systems play a role in postural control?

Afferent
- proprioceptive
- vestibular
- visual

Efferent
- muscular contraction

4

What are reactive responses?

- compensatory
- occur as reactions to external forces that displace the body's CoM

5

What are proactive responses?

- anticipatory
- occur in anticipation of internally generated destabilizing forces

6

What may happen to posture when an individual has altered or absent inputs? What are some examples of altered or absent inputs?

altered posture and stability is compromised

ex: decreased sensation of the lower extremities or post injury

7

What may happen to posture when an individual has altered or absent outputs? What are some examples of altered or absent outputs?

- compromise posture

ex: inability of muscles to respond appropriately to signals from CNS due to a neuromuscular disorder

8

What are sensory perturbations?

perturbations that may be caused by altering visual input

9

What are mechanical perturbations?

displacement causing changes in the relationship of the body's CoM to BoS

ex: leaning forward to the point you have to step forward to catch yourself

10

What are fixed support synergies/strategies?

Centrally organized patterns of muscle activity that occur in response to perturbations of standing postures

11

What are ankle strategies?

Discrete bursts of muscle activity that occur in a distal-to-proximal pattern

12

What are hip strategies?

Discrete bursts of muscle activity that occur in a proximal-to-distal pattern

13

What are change-in-support strategies?

movement to counteract large perturbations
- stepping strategies
- grasping strategies

14

What are stepping strategies?

forward, backward, or sidewise steps to increase BoS after large perturbation

15

What are grasping strategies?

using one's hands to grab a fixed surface after a large perturbation

16

What are internal forces vs external forces?

Internal forces - produced by muscle activity and passive tension in ligaments, tendons, and joint capsules

External forces - inertia, gravity, and ground reaction forces

17

Define ground reaction force

force of the ground pushing back on the body in standing

18

Define Line of Gravity

Line extending from center of gravity to the base of support

19

Define Center of Pressure

- Point of application of the GRFV – ground reaction force
- Located between the feet in bilateral stance

20

Describe the relationship of the position of the LOG and a joint axis

LoG THROUGH a joint = no torque

LoG at a DISTANCE = external gravitational moment

21

What impacts the magnitude and direction of the external moment?

Magnitude of the external moment increases as the distance between the LoG and joint axis increases

Direction depends on the location of the LoG in relation to the joint axis

22

Describe the alignment associated with ideal standing posture from a side view

- through external auditory meatus
- midway through the shoulder
- slightly posterior to hip
- slightly anterior to knee
- slightly anterior to lateral malleolus

23

Describe the alignment associated with ideal standing posture from a posterior view

Midline
- Head
- Spine
- Feet evenly spaced

Shoulder and scapula
- Scapulae lie flat on the thorax
- Approximately between T2 and T7
- Approximately 4 inches apart
- Shoulder ipsilateral to handedness is often lower – dominant hand shoulder is typically lower

24

Describe the alignment associated with ideal standing posture from an anterior view

Alignment of Knees
- Patellae face directly forward
- Slight physiological valgus

Alignment of Ankles
- Neutral- neither supinated or pronated

Alignment of Feet
- Heels separated by about 3 inches
- Out-toeing 8° - 10°

25

Where does LoG fall at lateral malleolus and what direction is the external moment? What is the internal moment?

LoG - slightly anterior

external moment - dorsiflexion

internal moment - plantarflexion

26

Where does LoG fall at the knee and what is the direction of the external moment? What is the internal moment?

LoG - anterior

external moment - extension

internal moment - flexion

27

Where does LoG fall at the hip and what is the direction of the external moment? What is the internal moment?

LoG - posterior

external moment - extension

internal moment - flexion

28

Where is LoG during swayback posture and what does this cause?

through the body of L5 causing slight extension moment
- creates shear ere is force rather than torque

29

Where does LoG fall at the head and neck and what is the direction of the external moment? What is the internal moment?

LoG - through external auditory meatus, anterior to axis for head

external moment - flexion of cervical spine

internal moment - extension of cervical spine

30

Where is the plumb line aligned in a side view? Where is the plumb line aligned in a posterior view?

side view
- just anterior to lateral malleolus

posterior view
- equidistant from each heel