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Kines Exam 2 > Posture > Flashcards

Posture Flashcards

1
Q

Body and its segments are aligned and maintained in a specific position (sitting, standing) is what type of posture?

A

Static

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2
Q

Body and its segments are moving (walking, running, squatting) is what type of posture?

A

Dyamic

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3
Q

what is meant by the base of support?

A

(BoS) - Area bounded posteriorly by the tips of the heels and anteriorly by a line jointing the tips of the toes

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4
Q

what is meant by the center of gravity?

A

(CoG) - Point where mass of the body is centered

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5
Q

Where does normal center of mass lie on humans?

A

CoM just anterior to S1/S2 vertebra

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6
Q

What does an assistive device do to our base of support?

A

Using an assistive device increases the size of an individual’s BoS, providing for more postural stability

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7
Q

What is the maintenance of center of mass (CoM) over base of support (BoS) to control body’s orientation in space and stabilize head with respect to vertical to orient gaze?

A

Postural Control

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8
Q

What portions of the central nervous system contribute to postural control?

A 
1. Afferent Inputs
	Somatosensory
	Vestibular
	Visual
2. Efferent Output
	Muscular contraction
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9
Q

What is reactive (compensatory) responses?

A

responses occur as reactions to external forces that displace the body’s CoM

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10
Q

What is proactive (anticipatory) responses?

A

responses occur in anticipation of internally generated destabilizing forces (raising arm to catch ball)

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11
Q

What is postural sway?

A

Small oscillations in which the body sways anteriorly, posteriorly, and side to side

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12
Q

Is it normal to have postural sway?

A

Up to 7 mm is normal during quiet stance

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13
Q

How do we determine sway?

A

Center of pressure through the feet can be mapped to determine sway

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14
Q

Increased sway = increased fall risk due to what?

A

CoM nearing or getting outside the BoS

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15
Q

What are common causes of increased sway?

A

o Hemiparesis
o Sensory Deficits
o Flat and high-arched feet
o Vestibular dysfunction

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16
Q

How do altered or absent inputs influence posture/balance?

A

Decreased sensation of the lower extremities or post-injury may alter posture and stability

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17
Q

How do absent or altered outputs influence posture/balance?

A

Inability of muscles to respond appropriately to signals from CNS due to a neuromuscular disorder

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18
Q

Maintenance of standing posture is the result of what type of controls?

A

Dynamic controls

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19
Q

What are sensory perturbations?

A

may be caused by altering visual input

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20
Q

What are mechanical perturbations?

A

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

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21
Q

What are common muscle strategies for responding to perturbations?

A

Synergies or strategies - Centrally organized patterns of muscle activity that occur in response to perturbations of standing postures

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22
Q

What are the two types of Synergies/strategies?

A
  1. Ankle

2. Hip

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23
Q

T/F Only ankle synergy has a fixed base of support

A

False, ankle and hip synergy have fixed base of support during perturbations and recovery

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24
Q

Ankle synergy are discrete bursts of muscle activity that occur in what type of pattern?

A

Distal to proximal pattern

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25
Q

Ankle synergy is for smaller/larger perturbations?

A

Smaller

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26
Q

What muscles are primarily activated during ankle strategies?
Forward sway -
Backward Sway -

A

Forward sway - gastroc, hamstrings, paraspinals

Backward Sway - tib ant, quads, abs

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27
Q

Hip synergy are discrete bursts of muscle activity that occur in what type of pattern?

A

Proximal to distal pattern

28
Q

Hip synergy is for smaller/larger perturbations?

A

Larger

29
Q

What muscles are primarily activated during hip strategies?
Forward sway -
Backward Sway -

A

Forward sway - abs, quads

Backward Sway - paraspinals, hamstrings

30
Q

What are stepping strategies?

A

Forward, backward or sidewise movement

31
Q

What are grasping strategies?

A

Using one’s hands to grab a fixed surface

32
Q

Stepping/grasping strategies (decrease/enlarge) body’s BoS so that it remains under the CoM

A

Enlarge

33
Q

T/F Changes in support strategies are the only ones that are successful with large perturbations.

A

True

34
Q

What are the differences between young and old individuals in stepping strategies?

A

Younger individuals usually only take 1 step whereas older individuals more commonly take multiple shorter steps

35
Q

Be able to explain the difference between internal and external forces in regard to posture.
What is each produced by?

A
  1. Internal force: produced by body structures:
    o Muscle activity and
    o Passive tension in ligaments, tendons and joint capsules
  2. External force: produced outside the body
    o Inertia
    o Gravity
    o Ground reaction forces
36
Q

When the sum of internal and external forces equal to zero?

A

Equilibrium

37
Q

What is a ground reaction force?

A

Ground Reaction Force Vector (GRFV) - Force of the ground pushing back on the body in standing

38
Q

What is the line of gravity?

A

Line of Gravity (LoG) - Line extending from center of gravity to the base of support

39
Q

What is the center of pressure?

A

Center of Pressure (CoP)
o Point of application of the GRFV
o Located between the feet in bilateral stance

40
Q

When the LoG passes directly through joint axis =

A

No torque created around the joint

41
Q

When the LoG passes at a distance from the joint axis =

A

external gravitation moment

42
Q

What will an external gravitational moment cause?

A

Results in rotation around the joint axis unless opposed by a counterbalancing internal moment or muscle contraction

43
Q

As the distance between the LoG and joint axis increase, what happens to the magnitude of the external moment are?

A

It will increase

44
Q

If LoG is anterior to the joint axis, an external moment will cause (ant/post) motion of (distal/proximal) segment supported by that joint?

A

Anterior motion of proximal segment

45
Q

In initial contact of gait, GRFV passes posterior to ankle creating ____ moment so we must create ____ moment to counter

A

External plantarflexion moment

Internal dorsal moment

46
Q

In initial contact of gait, GRFV passes anterior to the knee and hip creating ______ moment so we must create ____ moment to counter

A 
Knee - external extensor moment
Hip - External flexion moment
We must create:
Knee - internal flexion moment
Hip - internal extension moment
47
Q

What are the goals of performing a postural assessment?

A

o Appreciate static positioning of body segments with relation to each other
o Relate back to patient’s main complaints
o Apply to potential functional impairments

48
Q

What are the keys to success of performing a postural assessment?

A

o Assess from multiple angles
o Remove obstructive clothing
o Observe more than the area of complaint

49
Q

In ideal standing posture, LoG passes through or very close to all joint axes to do what?

A

Minimize external moments

50
Q

Large deviations from ideal standing posture result in -

A
  1. Excessive strain on passive structures

2. Increased muscular activity

51
Q

Long-term deviations from ideal standing posture result in -

A

Structural changes

52
Q

Where does the LoG pass through ankle in ideal standing posture? What external moment arm created?

A

Anterior to ankle joint axis

external moment arm - dorsiflexion

53
Q

What internal moment created at ankle in ideal posture? What structures contribute?

A

Internal moment = plantar flexion
o No passive structures contribute
o Active contraction of soleus, with contribution from gastrocnemius

54
Q

Where does the LoG pass through knee in ideal standing posture? What external moment arm created?

A

Passes anterior to midline of knee and posterior to patella (anterior to knee joint axis)
External moment: extension
 Possible additional extension moment contributed by soleus contraction

55
Q

What internal moment created at knee in ideal posture? What structures contribute?

A

Internal moment = flexion
 Passive tension of posterior joint capsule and associated ligaments
 Active contraction of hamstrings
 Active contraction of gastrocnemius

56
Q

Where does the LoG pass through hip in ideal standing posture? What external moment arm created?

A

Passes slightly posterior to axis of hip

External moment arm = extension (postural sway may cause LoG to pass anterior to create flexion moment)

57
Q

What internal moment created at hip in ideal posture? What structures contribute?

A

Internal moment = flexion
o Passive tension of hip ligaments
o Active contraction of iliopsoas

58
Q

Where does the LoG pass through Lumbosacral Joint in ideal standing posture? What external moment arm created?

A

LoG passes through body of L5 = slight extension moment

59
Q

When is pelvic tilt considered neautral?

A

When ASIS and pubic symphysis are in same frontal plane

60
Q

What structures contribute to internal moment arm at lumbosacral joint?

A

Creates shear force rather than true torque

o Opposed by anterior longitudinal ligament, iliolumbar ligaments, facet joint approximation

61
Q

Where does the LoG pass through head and neck in ideal standing posture? What external moment arm created?

A

Passes through external auditory meatus, anterior to axis for head
o External moment: flexion of cervical spine

62
Q

What internal moment created at head and neck in ideal posture? What structures contribute?

A

Internal moment: extension of cervical spine
o Passive tension of ligamentum nuchae, tectorial membrane and posterior facet joint capsules
o Active contraction of cervical extensors

63
Q

What is the ideal standing posture from the posterior view (midline and shoulder/scapula)?

A 
1. Midline
◦	Head
◦	Spine
◦	Feet evenly spaced
2. Shoulder and scapula
◦	Scapulae lie flat on the thorax
◦	Approximately between T2 and T7
◦	Approximately 4 inches apart
64
Q

What is the ideal standing posture from the anterior view?

  1. Alignment of Knees
  2. Alignment of Ankles
  3. Alignment of Feet
A 
1. Alignment of Knees
o	Patellae face directly forward
o	Slight physiological valgus
2. Alignment of Ankles
o	Neutral- neither supinated or pronated
3. Alignment of Feet
o	Heels separated by about 3 inches
o	Out-toeing 8° - 10°
65
Q

T/F relationship between CoM and BoS determine stability

A

True - can move depending on a variety of factors

66
Q

T/F Strategies will not change as we age

A

False, they will change as we age

Kines Exam 2 (6 decks)

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