Test 1 (Into, Musculoskeletal system, WMSD, Anthropometry, Range of Motion) Flashcards
(90 cards)
1
Q
Ergonomics Definition
A
Process of designing or evaluating products, tasks, environments and systems to improve performance and/or reduce risk of injury
2
Q
3 areas of ergonomics
A
- )Physical Ergonomics
- )cognitive ergonomics
- )Organizational ergonomics
3
Q
Types of Physical Ergonomics
A
- anthropometric (dimension conflicts)
- musculoskeletal (posture)
- metabolic/cardiovascular
- Environmental
4
Q
Ergonomic Process
A
- ) Characterize existing or potential problems.
- ) Perform job analysis
- ) Implement controls
- ) Evaluate the effectiveness of controls and educate employees
5
Q
Guiding principle of ergonomics
A
Maintain Demands < Capacity
6
Q
Hooke’s Law
A
y = Ex where stress = E(strain)
7
Q
Young’s Modulus
A
Slope of stress/strain curve (E)
8
Q
Yield Stress/Strain
A
Where blue meets red, point where less force is required to elongate, permanent change beyond
9
Q
Ultimate stress/strain
A
Right before negative slope
10
Q
Anisotropic
A
mechanical properties vary as a function of orientation with material
11
Q
Wolff’s Law
A
Bone adapts to its mechanical environment: added where needed and reabsorbed where not needed
12
Q
Ligaments connect ___ to ___
A
bone, bone
13
Q
Tendons connect ___ to ___
A
bone, muscle
14
Q
Viscoelasticity
A
Material response to force (or displacement) depends not only on force, but also time
15
Q
Creep
A
Given a constant force applied for an extended time, the material exhibits some additional strain over time before reaching steady-state length.
16
Q
Load (Stress) Relaxation
A
change in stress for a constant strain
17
Q
5 Structural units of skeletal muscle
A
muscle, fascicle, muscle fiber, myofibril, thick and thin filaments
18
Q
Muscle Fiber diameter
A
100 um diameter
19
Q
Sliding theory
A
muscles contract not because of shortening of individual myofilaments, but because they slide.
20
Q
Types of muscle contractions
A
isometric concentric, eccentric, isokinetic, isotonic
21
Q
isometric
A
constant length or joint angle
22
Q
eccentric
A
muscle lengthening due to an external load
23
Q
Muscle Grouping
A
co-contraction, agonist, antagonist
24
Q
Antagonist
A
opposes desired effort (good for stabiliztion)
25
Mechanical Properties of Muscle
force-length, force-velocity, force-activation
26
A motor unit
single nerve and all of the muscle fibers it innervates
27
Which muscle fibers are aerobic and which are anaerobic
1 = aerobic, 2 = anaerobic
28
Force-length relationship
looks like an n, amount of force produced depends on length. Capacity of generating force depends on posture.
29
WMSD abbr.
Work-related Musculoskeletal Disorder
30
What are WMSD
injuries to soft tissues that develop over time
31
Risk Factor
an individual characteristic or exposure associated with an increased risk of a disease or injury
32
3 types of Risk Factors for WMSD
Individual(intrinsic), Task-Related(extrinsic), Psychosocial
33
Examples of Individual Risk Factors
age, sex, obesity
34
Ex. of Task-related risk factors
awkward extreme postures, static work, vibration, environmental stress, high force exertions
35
Ex. of Psychosocial risk factors
mental stress, supervisory control, job security
36
Tendinitis
inflammation of tendon. (without sheaths), it is tenosynovitis if the tendon has a sheath
37
Importance of force-velocity relationship
The amount of force generated depends on how quick you are working. Faster work affects strength which is a capacity.
38
What is also a process for preventing WMSDs?
The ergonomics process. All of the steps are focused around risk factors.
39
What is the hierarchy of controls in order?
elimination, substitution, engineering controls, administrative controls, PPE
40
Awkward Posture
requires excessive effort against gravity, or other issue
41
Extreme Posture
At or near a joint's limit of motion
42
Why are awkward and extreme postures bad?
Both require more muscle effort, and that results in greater force on joints/tissues
43
What do we look for when analyzing awkward or extreme postures AND high force exertions AND contact force?
Determine frequency, duration and/or magnitude
44
How to calculate mechanical stress?
Force/cross-sectional area
45
Anthropometry definition
study of the physical dimensions of the human body
46
Static anthropometry
physical dimensions of the body (ie body segment length, mass, COM location, MOI)
47
What are the two types of anthropometric data
1. ) Static anthropometry
| 2. ) Functional or dynamic anthropometry
48
Functional anthropometry
physical dimensions for completion of particular activities (ie reach distance)
49
Units of mass
slug or kg
50
Center of mass
point at which all the mass of a body can be concentrated so that it results in external forces and moments equivalent to the actual distributed body
51
Design strategies for anthropometric variance
1. ) Design for the average
2. ) Design for extremes(max or min)
3. ) Design for adjustability
52
4 steps of percentile calculation
1. ) sketch distribution
2. )title distribution
3. ) include the mean, s, percentile of interest
4. ) SHADE the area of interest
53
Equation for percentile calculation
X = mean +/- Z*S
| on calc, use invNorm
54
Why evaluate ROM and strength
1. ) Identify high-risk work tasks
2. ) Identify high-risk workers
3. )Assess "return to work" status
4. ) Help improve understanding how risk factors affect capacity
55
Definition of Joint Range of Motion
Maximum possible angular deviation of segments forming a joint
56
What are the 2 types of ROM measurements
1.) Active ROM: muscle force used to reach ROM limits
2.) Passive ROM: external force used to reach limit.
Active ROM
57
What is Anatomical Position
A universally accepted reference position. Standing normally with feet together palms facing forward and thumbs away from body
58
What are the anatomical planes of motion
1. )Sagittal Plane
2. )Frontal Plane
3. ) Transverse Plane
59
What movements occur in sagittal plane?
flexion and extension
60
What movements occur in the frontal plane?
abduction and adduction
61
What movements occur in the transverse plane?
Rotation
62
Definition of Muscle Strength
Maximum force/moment a group of muscles can develop under prescribed conditions.
63
What are the types of strength measurements
1. ) Isometric (static)
2. ) Dynamic (isokinetic or free dynamic)
3. ) Psychophysical (subjective)
64
What are some things that affect strength
posture, sex, age, obesity
65
What are the types of interactions that are typical in ergonomic studies?
Human with machine, machine with human, environment with human
66
Definition of stress as a property of bone
Force/initial cross sectional area
67
Definition of strain as a property of bone
Change in length/original length
68
Structural differences between ligaments and tendons
Tendon: parallel bundles of collagen fibers
Ligaments: nearly parallel bundles of collagen fibers
69
What is cartilage
smooth elastic tissue that covers the ends of long bones at joints to provide a low-friction for movement.
70
What is fascia
a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs
71
Types of joints
Cartilage, synovial, and fibrous
72
Intervertebral Discs are composed of
Nucleus pulposus(gel-like material) and annulus fibrosus (connective tissue)
73
Ex. of Back WMSD and contributing factors
Degenerative disc disease, herniated disc ligament sprain
Prolonged static load, award posture, repetitive lifting
74
What are muscle spindles?
Specialized muscle fibers that provide CNS feedback on muscle strain and strain rate
75
What are Golgi Tendon Organs
provide CNS feedback on muscle force. Oriented in series with muscle. Could play role in strength testing due to its inhibitory action.
76
Shoulder WMSD. Examples and contributing factors
Ex. shoulder or rotator cuff tendonitis
FActors: prolonged shoulder flexion/abduction, frequent reaching above the shoulders, prolonged load on shoulders, repetitive throwing of heavy loads.
77
What are triggers to start the ergonomic process
injuries, employee/supervisor concerns, bottlenecks, quality problems
78
What are some tools to start the ergonomic process
employee interviews, review company medical claims, review safety committee meeting minutes, review OSHA 300 reports
79
Questions to ask during step 4 of economic process involving WMSD.
Did you reduce or create new risk factors? Are workers feeling better? do the employees have a basic awareness of ergonomic principle?
80
What do high force exertions cause?
high muscle effort, increased force on joints/tissues, increased risk of muscle fatigue, reduced/no circulation, increased risk of chronic muscle, tendon, and nerve disorders
81
What are some controls for high force exertions?
enhance or reduce friction where appropriate, pick up fewer objects at a time, select lighter tools, use hoists or articulated arms to support objects...........
82
What are some controls for high repetition or sustained exertions or postures?
adjust the work rate, use mechanical aids, use worker rotation, use work enlargement
83
What are some controls for contact mechanical stress?
elongated handles, rounded edges, compliant handle material, lower force requirements
84
What are some limitation of using Anthro data to design
- population-based data can have selection bias
- averages and proportions don't represent individuals
- functional data may vary with things
- even if guidelines are followed, the workstation may not be completely functional or comfortable
85
When is a D vs C comparison done?
When considering a risk factor that is an exposure
86
What are some methods to measure joint angle
manual goniometer or electrogoniometer, inclinometer
87
What individual risk factors affect ROM?
Age, sex, training, joint or muscle pathology, genetics
88
What are the adv and disadv of isometric strength measurements
adv: simplicity, cheap
disadv: poor association with dynamic performance
89
Adv and disadv of dynamic strength measurements
adv: more realistic
disadv: more difficult
90
adv and disadv of psychophysical strength measurements
adv: mimics actual task well
disadv: workers may have difficulty extrapolating or judging, sensitive to variables
