Lecture 2: Definitions Flashcards

1
Q

Biomechanics

A

application of physics to the understanding of the motions and deformations of body segments, organs, structures, tissues, cells due to forces, pressures, torques, shears, etc

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2
Q

Linked rigid body biomechanics

A

Rigid bodies are linked at joints
- bones are rigid and muscles deform

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3
Q

Rigid body

A

mass with a volume

assumption that segments btwn links are rigid = not actually rigid

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4
Q

Advantages/disadvantages for X-Rays with biomecahnics

A

no error w/ soft tissue motion

drawbacks: exposure to ionizing radiation
- have to time amount of exposure

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5
Q

Skeletal biomechanics

A

Deformation of the FACIAL SKELETON after getting hit in the face

  • facial skeleton deforms a lot (everyday when chewing)
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6
Q

Facial fractures

A

heal well b/c face is highly vascularized

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7
Q

Vascular biomechanics

A

Modeling BOTH the DEFORMATION of the wall of a blood vessel and the BLOOD FLOW within the vessel

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8
Q

Cellular biomechanics

A

Measuring the FORCES with which cells interact w/ their surroundings

Cells can bear and exert force

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9
Q

Assumptions with linked rigid body biomechanics

A
  1. Body segments are RIGID
  2. Segments connect at JOINTS
  3. Joints have a well-defined number of ‘DEGREES OF FREEDOM’
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10
Q

Degrees of freedom

A

6 total degrees of freedom (3 linear + 3 rotational)

If there are 6 degrees, 2 rigid bodies are NOT attached
- need to constrain at least one degree of freedom to be attached

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11
Q

Max degrees of freedom is needed for a joint?

A

Maximum is 5 degrees b/c at least one has to be constrained

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12
Q

Example of joint with 5 degrees of freedom

A

Temporal mandibular jaw (btwn face and jawline)
- 3 rotational and 2 linear

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13
Q

Degrees of freedom: Hip

A

Hip has 3 degrees of ROTATIONAL freedom (flex/extend, adduct/abduct, internal/external rotation)

NO linear degrees of freedom

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14
Q

Degrees of freedom: Knee

A

Knee is a hinge jt. = 1 degree of freedom (ONLY flexion/extension)

doesn’t move in any other degrees (constrained by bony congruents or ligaments)
- linear degrees constrained by ACL/PCL

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15
Q

Applications of linked rigid body mechanics

A
  • coaching
  • rehab
  • orthopaedic
  • ergonomics in workplace
  • clothing/fashion
  • animation (CGI)
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16
Q

Anthropometrics

A

Measurements of physical characteristics of the human body

  • height and weight (easy to measure)
  • body segment lengths, weights, volumes, shapes (uses cadavers)
  • location of centre of mass
  • moments of inertia
17
Q

Moments of inertia

A

Bigger moment of inertia = harder to rotate

Smaller moment of inertia = easier to rotate

18
Q

Mechanics

A

Physics of forces and motion

2 categories: statics and dynamics

19
Q

Statics

A

the study of bodies WITHOUT acceleration

NO inertia

  • not necessarily still/at rest
20
Q

Dynamics

A

the study of bodies WITH acceleration

Correct way to analyze biomechanics but trickier

21
Q

Acceleration

A

Linear motion

Time rate of change of velocity (2nd derivative of position)

Need to apply a FORCE

measured in m/s^2

22
Q

Velocity

A

Linear motion

Time rate of change of position (1st derivative of position)

measured in m/s

23
Q

Position

A

Linear motion

in meters (m)

24
Q

Angular acceleration

A

Time rate of change of angular velocity

in degrees/s^2

25
Q

Linear and rotational motion relationship

A

Linear and rotational motion are INDEPENDENT of each other

But both are present

26
Q

Kinematics

A

Study of GEOMETRY of motion

Position, velocity, acceleration

Angle, angular velocity, angular acceleration

27
Q

Kinetics

A

studies CAUSES of motion

Force, pressure, torque, tension, shear, compression

28
Q

Inverse kinetics/dynamics

A

Measure KINEMATICS FIRST then work ‘backwords’ to figure out kinetics that must have caused motion

EASIER TO DO IN LAB

29
Q

Forward kinetics/dynamics

A

Measure KINETICS FIRST then try to figure out where the body is going to go

  • really hard to do in lab
  • how you learned to work