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Biomechanics Winter 2024 > Intro to Biomechanics > Flashcards

Intro to Biomechanics Flashcards

1
Q

What is kinesiology?

A
  • the study of movement
  • what happens with the body during movement
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2
Q

What is biomechanics?

A
  • the study of forces applied to the outside and inside of the body and the bodies reaction to those forces
  • uses physics
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3
Q

What is the difference between kinematics and kinetics?

A

Kinematics:
- describes motion of the body WITHOUT regard to the forces/torques that may produce the motion

Kinetics:
- describes the effect of forces on the body
- includes forces, torques, physics principles

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4
Q

Is naming the plane of motion considered part of kinetics or kinematics?

A

kinematics
- it focuses on the movement of the body WITHOUT taking force into account

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5
Q

What are rotary movements?

A
  • this is an angular displacement (uses a pivot point)
  • rigid body moves in a circular path around a pivot point
  • ROTATE in same angular direction and same number of degrees
    measured in degrees or radians
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6
Q

What are translatory movements?

A
  • this is linear displacement (gliding or sliding)
  • all parts of a rigid body move parallel to and in the same direction
  • Rectilinear (straight line) or curvilinear (curved line)
  • measured in meters or feet
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7
Q

What are the main differences in how rotary and translatory motions are performed in the body?

A

Rotary:
- more from muscle stimulation

Translatory:
- are more passive

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8
Q

What is an axis of rotation?

A
  • pivot point for angular motion
  • usually through a joint (or very close to it)
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9
Q

What is an evolute axis of rotation?

A
  • a migrating axis of rotation
  • AoR will stay in one place only if bone is completely circular
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10
Q

How does active movement differ from passive movement?

A

Active: caused by stimulated muscle

Passive: caused by sources other than stimulated muscle (therapist does movement)

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11
Q

Explain the frontal cardinal plane

A

splits body/body part into anterior and posterior (front and back)

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12
Q

What axis of rotation is usually associated with the frontal plane?

A
  • sagittal AoR
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13
Q

Explain the sagittal plane

A
  • splits the body/body part into left and right halves
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14
Q

What axis of rotation is usually associated with the sagittal plane?

A
  • frontal AoR
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15
Q

Explain the transverse (horizontal) plane

A
  • splits the body/body part into superior and inferior (top and bottom)
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16
Q

What axis of rotation is usually associated with the transverse (horizontal) plane?

A
  • vertical AoR
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17
Q

What member of the joint does the AoR usually run through?

A
  • usually the convex member of the joint
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18
Q

What is degrees of freedom?

A
  • number or independent directions of movements allowed at a joint
  • can have up to 3 degrees of freedom that corresponds with the cardinal planes
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19
Q

What usually occurs if a joint loses a degree of freedom?

A
  • this greatly inhibits the joints normal function
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20
Q

Define a uniaxial joint

A
  • 1 plane
  • 1 axis
  • 1 degree of freedom
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21
Q

Define a biaxial joint

A
  • 2 planes
  • 2 axis
  • 2 degrees of freedom
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22
Q

Define a triaxial/multiaxial joint

A
  • 3 planes
  • 3 axis
  • 3 degrees of freedom
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23
Q

What is osteokinematics?

A
  • motion of bones relative to the 3 cardinal planes
  • movement occurs b/w shafts of 2 adjacent bones as they move
  • PROM (rotary)
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24
Q

What is arthrokinematics?

A
  • motion that occurs b/w the articular surfaces of joints
  • focuses specifically on the minute movements occuring within the joint and b/w joint surfaces
  • joint mobilizations
  • rotary or translatory
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25
Q

What is meant by end feel?

A
  • a joints resistance to further motion
  • dictated by joint structure
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26
Q

What are some normal and abnormal end feels?

A

Normal:
- hard or bony
- firm or capsular
- soft

Abnormal:
- empty
- pain until end of motion
- anything that is abnormal for that joint

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27
Q

What is the difference between open and closed chained kinematic movements?

A

Open:
- distal segment free
- usually distal on proximal
- kicking

Closed:
- proximal segment free
- usually proximal on distal
- pushups

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28
Q

What movements are considered arthrokinematic movements?

A
  • Roll
  • Slide
  • Spin
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29
Q

What is the Convex-Concave rule?

A

Convex-on-concave
- roll one way
- slides the opposite way
- must occur in order to stay in the joint

Concave-on-convex
- rolls and slides in the same direction
- can roll and slide around the convex surface

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30
Q

What are the characteristics of a close-packed position?

A
  • position of max congruency
  • most ligaments/capsules taut
  • mechanically compressed (hard to seperate)
  • stable
  • generally near end range
  • reduced need for muscle forces
  • LE associated with habitual function
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31
Q

What are the characteristics of an open-packed position (loose-packed position)?

A
  • joint surfaces incongruent
  • ligaments/capsules most lax
  • joint cavity has greatest volume
  • usually least congruent near midrange
  • LE biased toward flexion
  • usually preferred during long periods of immobilization
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32
Q

Define force

A
  • push or pull that can produce, arrest, or modify movement
  • also called “load”
33
Q

What is the stress-strain curve?

A
  • this is a curve showing a muscle’s ability to lengthen until it reaches its failure point
34
Q

What does stress mean in the stress-strain curve?

A
  • the resistance of the tissue to the force that is being applied to the tissue
35
Q

What does strain mean in the stress-strain curve?

A
  • the percent increase in stretch to the tissue length relative to its original length
36
Q

What does the “toe” region mean in the stress-strain curve?

A
  • the initial wavy or crimped tissue that must become taut before tissue is measured
37
Q

What does the elastic region mean in the stress-strain curve?

A
  • the region where stress is being added to a tissue but length of tissue will return to normal after the force has been removed from the tissue
38
Q

What does the yield point mean in the stress-strain curve?

A
  • the tissue is elongated to a point where no stress/resistance occurs but continues to elongate
  • strain continues but stress does not
  • pulling laffy taffy apart to the point it is super stringy
39
Q

What does the plastic region in the stress-strain curve mean?

A
  • strain continues and microscopic failures begin to form
  • tissue cannot return to normal and stays deformed
40
Q

What is the ultimate failure point in the stress-strain curve?

A
  • point when the tissue fails/tears
41
Q

At what point do tendons usually fail at?

A
  • fail at 8-13% beyond pre-stretch length
42
Q

What does the rate of loading pertain to?

A
  • for viscoelasticity properties
  • faster you load something the more resistance it gives back
  • protective mechanism AS LONG AS it is in elastic range
43
Q

What is viscoelasticity?

A
  • this is property of tissue
  • it is elastic and viscous at the same time
  • allows the tissue to return back to normal as long as still within the elastic region
44
Q

What is creep?

A
  • actual elongation of tissue when exposed to a constant load over time
45
Q

What does “elastic” mean when it pertains to muscle deformation?

A
  • muscles will return to normal length after stretch has finished
46
Q

What does “plastic” mean when it pertains to muscle deformation?

A
  • muscles will NOT return to normal length after stretch has finished
47
Q

Explain Newtons first law of motion

A

Law of Inertia:
- Linear: body remains at rest or at constant linear velocity except when compelled by an external force
- hockey puck

  • Angular: body remains at rest or at constant angular velocity around AoR unless compelled by external torque
  • merry-go-round
48
Q

Explain Newtons second law of motion

A

Law of Acceleration:
- Linear: DIRECTLY proportional to the force causing it and takes place in same direction as the force acts and is INVERSELY proportional to mass
- a=F/M

  • Angular: DIRECTLY proportional to the torque causing it and takes place in same rotary direction as torque acts and is INVERSELY proportional to the mass moment of inertia of the body
  • (a=T/I)
49
Q

Explain Newtons third law of motion

A

Action-Reaction:
- Linear: for every force there is an equal and opposite directed force

-Angular: for every torque there is an equal and opposite directed torque

50
Q

Define Center of Mass

A
  • center of gravity
  • hypothetical point at which all the mass of an object appears to be concentrated (balancing point)
51
Q

What is the line of gravity

A
  • LoG
  • gravitational vector always vertically downward like a plumb line
52
Q

What is the mass moment of inertia?

A
  • an object’s resistance to rotary motion or change in rotary motion
53
Q

What is inertia?

A
  • the amount of energy required to alter the velocity of a body
  • directly proportional to mass
  • an object in motion will resist any increase, decrease, or change in motion
54
Q

What are the different equations for speed, velocity, and acceleration?

A

Speed = distance/time
- no direction, scalar

Velocity = distance/time
- with direction, vector

Acceleration = change in velocity/time
- vector, linear angular

55
Q

What would happen to an arms CoM and muscles if weight is added to the wrist?

A

CoM: would move toward the wrist due to the increased weight

Muscles: it would make the muscles work harder due to added weight and an increase in the moment arm

56
Q

What is the relationship between CoM and Mass Moment of Inertia?

A
  • CoM affects Mass Moment
  • closer composite CoM is for each extremity (U + L) the faster velocity will be (this creates less resistance to wind)
  • further away, the slower rotary velocity will be
57
Q

How does the acceleration of an object change if the force to move it remains constant but the mass of the object decreases?

A
  • acceleration will increase because the force remains constant while decreasing the weight being pulled
58
Q

Would force need to increase or decrease from the quads when changing a 5 pound weight from knee Ext to lifting a 10 pound weight if movement speed stayed the same?

A
  • force would need to increase
59
Q

What is an internal force?

A
  • produced from structures in the body
  • active or passive
60
Q

What is an external force?

A
  • produced by forces acting from outside the body
  • gravity or external load
61
Q

What is joint reaction force (JRF) compared to ground reaction force (GRF)

A

Joint Reaction Force:
- joints pushing back against gravity and body weight
- caused in reaction to other forces
- muscle activation, passive tension in connective tissue

Ground Reaction Force:
- ground generates force in opposite direction but EQUAL in magnitude

62
Q

What is a vector?

A
  • a quantity with magnitude and direction
  • shown using arrows
63
Q

What characteristics apply to all force vectors?

A
  • magnitude (size and length)
  • direction (arrowhead pointing)
  • spatial orientation (arrow shaft position)
  • point of application (arrow base contacts segment)
  • angle of insertion (angle formed between tendon and long axis of bone at insertion
64
Q

How can a joint be in static linear equilibrium?

A
  • when sum of forces = 0
  • JRF + Internal + External forces = 0
  • Forces equal each other
65
Q

Define torque

A
  • force in rotary direction
66
Q

What orientation will produce the best torque?

A
  • being perpendicular to the moment arm
67
Q

How can a joint be in static rotary equilibrium?

A
  • Internal torque + External torque = 0
68
Q

Define a “moment arm”

A
  • perpendicular distance between AoR and the force
69
Q

What is an Internal moment arm (IMA)?

A
  • from AoR to Internal force
70
Q

What is an External moment arm (EMA)?

A
  • from AoR to External force
71
Q

What is Internal and External torque?

A

Internal Torque:
= Internal Force x IMA

External Torque:
= External force x EMA

72
Q

What size moment arm creates the most leverage?

A
  • a longer moment arm will create more leverage
  • a shorter moment arm will create less leverage
73
Q

How does moment arm affect the ability of a force to rotate a segment?

A
  • this can determine leverage
  • shorter a moment arm, the less leverage which means force isn’t as effective at producing
74
Q

What is a force couple?

A
  • when 2 or more muscles simultaneously produce forces in different linear directions BUT result in same rotary direction
75
Q

Describe a first class lever

A
  • AoR is b/w IMA & EMA
  • seesaw
  • mechanical advantage can be =, >, < 1
  • cervical head nodding
76
Q

Describe a second class lever

A
  • EMA is b/w AoR & IMA
  • wheel barrows
  • Mechanical advantage always > 1
  • gastrocnemius & soleus plantar flexion
77
Q

Describe a third class lever

A
  • IMA + IF is b/w AoR & EF + EMA
  • mechanical advantage always < 1
  • deltoids
78
Q

Which system allows for a greater arc of motion or angular displacement?

A
  • 3rd class will allow a greater arc of motion
  • because IMA is closer to the AoR allowing for more motion & angular displacement
79
Q

What factors can cause the net torque on a segment to change?

A
  • length of EMA
  • Force of EF
  • Force of IF

Biomechanics Winter 2024 (6 decks)

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