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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
Ankle synergy is for smaller/larger perturbations?
Smaller
26
What muscles are primarily activated during ankle strategies? Forward sway - Backward Sway -
Forward sway - gastroc, hamstrings, paraspinals | Backward Sway - tib ant, quads, abs
27
Hip synergy are discrete bursts of muscle activity that occur in what type of pattern?
Proximal to distal pattern
28
Hip synergy is for smaller/larger perturbations?
Larger
29
What muscles are primarily activated during hip strategies? Forward sway - Backward Sway -
Forward sway - abs, quads | Backward Sway - paraspinals, hamstrings
30
What are stepping strategies?
Forward, backward or sidewise movement
31
What are grasping strategies?
Using one's hands to grab a fixed surface
32
Stepping/grasping strategies (decrease/enlarge) body's BoS so that it remains under the CoM
Enlarge
33
T/F Changes in support strategies are the only ones that are successful with large perturbations.
True
34
What are the differences between young and old individuals in stepping strategies?
Younger individuals usually only take 1 step whereas older individuals more commonly take multiple shorter steps
35
Be able to explain the difference between internal and external forces in regard to posture. What is each produced by?
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
When the sum of internal and external forces equal to zero?
Equilibrium
37
What is a ground reaction force?
Ground Reaction Force Vector (GRFV) - Force of the ground pushing back on the body in standing
38
What is the line of gravity?
Line of Gravity (LoG) - Line extending from center of gravity to the base of support
39
What is the center of pressure?
Center of Pressure (CoP) o Point of application of the GRFV o Located between the feet in bilateral stance
40
When the LoG passes directly through joint axis =
No torque created around the joint
41
When the LoG passes at a distance from the joint axis =
external gravitation moment
42
What will an external gravitational moment cause?
Results in rotation around the joint axis unless opposed by a counterbalancing internal moment or muscle contraction
43
As the distance between the LoG and joint axis increase, what happens to the magnitude of the external moment are?
It will increase
44
If LoG is anterior to the joint axis, an external moment will cause (ant/post) motion of (distal/proximal) segment supported by that joint?
Anterior motion of proximal segment
45
In initial contact of gait, GRFV passes posterior to ankle creating ____ moment so we must create ____ moment to counter
External plantarflexion moment Internal dorsal moment
46
In initial contact of gait, GRFV passes anterior to the knee and hip creating ______ moment so we must create ____ moment to counter
``` Knee - external extensor moment Hip - External flexion moment We must create: Knee - internal flexion moment Hip - internal extension moment ```
47
What are the goals of performing a postural assessment?
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
What are the keys to success of performing a postural assessment?
o Assess from multiple angles o Remove obstructive clothing o Observe more than the area of complaint
49
In ideal standing posture, LoG passes through or very close to all joint axes to do what?
Minimize external moments
50
Large deviations from ideal standing posture result in -
1. Excessive strain on passive structures | 2. Increased muscular activity
51
Long-term deviations from ideal standing posture result in -
Structural changes
52
Where does the LoG pass through ankle in ideal standing posture? What external moment arm created?
Anterior to ankle joint axis | external moment arm - dorsiflexion
53
What internal moment created at ankle in ideal posture? What structures contribute?
Internal moment = plantar flexion o No passive structures contribute o Active contraction of soleus, with contribution from gastrocnemius
54
Where does the LoG pass through knee in ideal standing posture? What external moment arm created?
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
What internal moment created at knee in ideal posture? What structures contribute?
Internal moment = flexion  Passive tension of posterior joint capsule and associated ligaments  Active contraction of hamstrings  Active contraction of gastrocnemius
56
Where does the LoG pass through hip in ideal standing posture? What external moment arm created?
Passes slightly posterior to axis of hip | External moment arm = extension (postural sway may cause LoG to pass anterior to create flexion moment)
57
What internal moment created at hip in ideal posture? What structures contribute?
Internal moment = flexion o Passive tension of hip ligaments o Active contraction of iliopsoas
58
Where does the LoG pass through Lumbosacral Joint in ideal standing posture? What external moment arm created?
LoG passes through body of L5 = slight extension moment
59
When is pelvic tilt considered neautral?
When ASIS and pubic symphysis are in same frontal plane
60
What structures contribute to internal moment arm at lumbosacral joint?
Creates shear force rather than true torque | o Opposed by anterior longitudinal ligament, iliolumbar ligaments, facet joint approximation
61
Where does the LoG pass through head and neck in ideal standing posture? What external moment arm created?
Passes through external auditory meatus, anterior to axis for head o External moment: flexion of cervical spine
62
What internal moment created at head and neck in ideal posture? What structures contribute?
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
What is the ideal standing posture from the posterior view (midline and shoulder/scapula)?
``` 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
What is the ideal standing posture from the anterior view? 1. Alignment of Knees 2. Alignment of Ankles 3. Alignment of Feet
``` 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
T/F relationship between CoM and BoS determine stability
True - can move depending on a variety of factors
66
T/F Strategies will not change as we age
False, they will change as we age

Kines Exam 2 (6 decks)

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