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Biomechanics final review > Biomechanics Final Review > Flashcards

Biomechanics Final Review Flashcards

1
Q

What are statics?

A

Body is at rest

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2
Q

What are dynamics?

A

Body is in motion

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3
Q

What is the description of the movement of the human body as a whole?

A

Translation of the center of mass

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4
Q

What is movement powered by?

A

Muscles that rotate the limbs

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5
Q

What is rotation of a joint called in biomechanics? Why?

A
  • Angular motion
    Because it has an axis
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6
Q

What is an axis?

A

The pivot point for angular motion of the whole body or body segments

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7
Q

What is the motion of the rotating body at the axis?

A

zero

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8
Q

What is a kinematic chain?

A

A series of articulated segmented links

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9
Q

What are the two perspectives of a movement at a joint?

A
  1. proximal segment rotating on fixed distal segment
  2. distal segment rotating on fixed proximal segment
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10
Q

What are the two persectives for knee flexion?

A
  1. femoral - on - tibial movement
  2. tibial on femoral movement
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11
Q

What is roll in arthrokinematics?

A

multiple points along one rotating surface contact multiple points on another articular surface

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12
Q

What is slide in arthrokinematics?

A

A singular point on one articular surface contacts multiple points on another articular surface

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13
Q

What is the roll and slide of a convex on concave joint?

A

Rolls and slides opposite directions

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14
Q

What is the rolls and slide of a concave on convex joint?

A

Rolls and slides same

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15
Q

What are kinetics?

A

The effect of forces on the body

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16
Q

What is a force?

A

A push or pull that can produce/arrest/ or modify movement

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17
Q

What is the standard unit of force?

A

Newtons

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18
Q

What is the force on the body?

A

Load

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19
Q

What does force do?

A

Move, fixate, stabilize (also potential to deform/injure)

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20
Q

What type of force can happen in a car accident?

A

Shear

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21
Q

What kind of force happens to the anterior disc during neck flexion?

A

Bending

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22
Q

What kind of force happens to the posterior disc during neck flexion?

A

Tension

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23
Q

What kind of force happens with rotation and extension of the neck?

A

Combined loading

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24
Q

What is the ability of the periarticular connective tissues to accept and disperse loads impacted by?

A

Aging, trauma, prolonged immobilization, disease

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25
Q

What is X in a stress strain curve?

A

The % increase in a tissue related to the original length

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26
Q

What is Y in a stress strain curve?

A

The internal resistance generated as it is resisting deformation

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27
Q

What is a toe region in a stress strain curve?

A

Collagen fibers are crimped

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28
Q

What is the elastic region in a stress strain curve?

A

return to original length and energy is recovered

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29
Q

What is the plastic region in a stress strain curve?

A

Plastic deformation - energy lost

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30
Q

What is the ultimate failure point for tendons?

A

8-13%

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31
Q

What is the yield point in a stress strain curve?

A

The point at which it turns from elastic to plastic

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32
Q

What is creep?

A

Increasing deformation under constant load

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33
Q

What is internal torque?

A

Internal force and internal moment arm

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34
Q

What is external torque?

A

External force (gravity) and external moment arm

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35
Q

What happen if internal torque and external torque are equal?

A

Rotary equilibrium

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36
Q

What is leverage?

A

Moment arm length possessed by a particular force, changes throughout the ROM

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37
Q

What is FY in a force diagram?

A

Force that rotates

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38
Q

What is F in a force diagram?

A

The muscle

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39
Q

What is FX in a force diagram?

A

Compressing or distracting joint

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40
Q

What is an isometric muscle activation?

A

Maintains a constant length; internal = external torque

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41
Q

What is a concentric muscle activation?

A

Muscle shortens; internal torque is more than external; rotation in direction of activated muscle

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42
Q

What is a eccentric force?

A

Muscle lengthens as it is being elongated by another more dominant force; external torque is more than internal torque; joint rotation is dictated by external torque

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43
Q

What is an agonist?

A

Muscle that initates or executes the particular movement

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44
Q

What is an antagonist?

A

Opposite action of a particular agonist

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45
Q

What is a synergist?

A

Cooperating muscles for execution of a particular movement

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46
Q

What is a force couple?

A

2 or more muscles produce forces in different linear directions - resulting torques act in same rotary direction

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47
Q

What is an evolute?

A

The path of serial locations for the instantaneous axis of rotation

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48
Q

What happens to the path of the evolute when the opposing joint surfaces are less congruent?

A

Longer and more complex

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49
Q

What are goniometric measures?

A

An estimate of the average axis of rotation that is used

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50
Q

When is the estimate of the IAR more accurate?

A

The smaller the angular range

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51
Q

What is collagen made up of structurally?

A

A triple helix

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52
Q

If stress is always in the same direction, what will the collagen fibers do?

A

Orient themselves to run paralell

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53
Q

If the stress is in different directions, it leads to what? ( in terms of collagen)

A

Interlaces lattice effect

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54
Q

What are the 2 basic elements of connective tissue?

A

Cells and extra-cellular matrix made of fibrous components and ground substance

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55
Q

What is ground substance?

A

A water saturated matrix or gel

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56
Q

What gives ground substance physical resilience?

A

GAGs

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57
Q

What is associated with the matrix? Why?

A

A large quantity of water - as a function is to enable diffusion of nutrients and waste products and friction free movement of fibers

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58
Q

What does the ground substance do?

A

Transmits loads

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59
Q

What is the composition and role of the matrix determined by?

A

The stress that impacts the cells

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60
Q

What do GAGs do?

A

Give physical resiliance

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61
Q

What are GAGs?

A

Glycoaminoglycans - large protoglycan complex

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62
Q

How does cartilage get nutrition?

A

Milking action via synovial fluid caused by intermittent joint loading

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63
Q

What happens to the large proteoglycan complexes in regards to nutrition of the cartilage?

A

They are trapped, attract water, but repel eachother

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64
Q

What helps the PGs protect the cells from outside forces?

A

The stiffness and hydrophilic nature of the sugar chains

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65
Q

What does the nutrition to the cartilage do?

A

Increases the capacity for loads

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66
Q

What do bone spurs form from?

A

Increased spinal stresses

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67
Q

Where is bone laid down?

A

Areas of high stress

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68
Q

Where is bone reabsorbed?

A

Areas of low stress

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69
Q

What are obeoblasts constantly doing?

A

Synthesizing ground substance/collagen; deposition of salts

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70
Q

What do osteoclasts do?

A

Remove bone

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71
Q

What do osteoblasts do?

A

Lay down new bone

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72
Q

What happens with immobilization?

A

marked changes in the structure and function of connective tissues - loss of mass, volume, and strength

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73
Q

What happens with mechanical strength with immobilization?

A

Reduced

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74
Q

How long until mechainical strength is lost with immobilizaiton?

A

within days

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75
Q

What should we know about the recovery after immobilizaiton?

A

Slow - often incomplete

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76
Q

What is aging accompanied by?

A

A slowing of the rate of fibrous proteins and proteoglycan replacement and repair in all periarticular tissues and bone

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77
Q

What does aging cause us to use in terms of forces?

A

Loss of ability to restrain and disperse forces - microtrauma

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78
Q

How can we mitigate the effects of aging?

A

Physical activity and resistance training

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79
Q

What is endomysium?

A

A thin layer of connective tissue that surrounds an individual muscle cell/fiber; external to the sarcolemma

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80
Q

What does endomysium do?

A

Helps transfer the contractile force inside it from the actin/myosin to the tendon

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81
Q

What is the perimysium?

A

A sheath of connective tissue surroudning a bundle of muscle fibers (fascicle)

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82
Q

What does the perimysium do?

A

Provides a conduit for blood vessels and nerves; tough and resiliant to stretch

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83
Q

What is the epimysium?

A

A sheath of fibrous elastic tissue surrounding a muscle belly

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84
Q

What should we know about the epimysium ?

A

Resistant to stretch

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85
Q

What are contractile proteins?

A

Actin
myosin

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86
Q

What are non-contractile proteins?

A

Cytoskeleton within muscle fibers
supportive structure between fibers

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87
Q

What do non-contractile proteins do?

A

Play a role in transmission of force but do not contract

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88
Q

What provides passive tension within the muscle cell?

A

Titin

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89
Q

What stabilizes the alignment of adjacent sarcomeres?

A

Desmin

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90
Q

What is a fusiform muscle?

A

Fibers run parallel to one another and to a central tendon

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91
Q

What are fusiform muscles designed for?

A

Mobility, low force over long range

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92
Q

What are pennate muscles?

A

Fibers approach their central tendon obliquey, contain a larger number of fibers per area

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93
Q

What do pennate muscles do?

A

generate larger forces

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94
Q

What type of muscle are most muscles in the body?

A

Pennate

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95
Q

What does a physiologic cross-section area tell us?

A

The amount of active proteins available to generate active force

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96
Q

What is a max force potential of a muscle proportional to?

A

the sum of the cross sectional area of all its fibers

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97
Q

What is a pennation angle?

A

The angle of orientation between the tendon and the fibers

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98
Q

Which type of muscle fires quicker?

A

Fusiform

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99
Q

Most muscles have pennation angles between __ and __

A

0 and 30

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100
Q

What is a series?

A

All components are connected end to end forming a single path

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101
Q

What is a parallel?

A

All components connected across each other

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102
Q

What is a series elastic component?

A

Tissues attached end to end with the active proteins: tendon, titan

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103
Q

What is a parallel active component?

A

Tissues lie parallel with active proteins: epi/peri/endomysium

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104
Q

What does a stretched muscle do?

A

Has elasticity and temporarily stores a fraction of the energy that created the stretch

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105
Q

Muscle is viscoelastic, what does this mean?

A

Time changes its behaviour

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106
Q

What is elasticity in terms of protection?

A

Dampening mechanism, protects muscle

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107
Q

When are muscles loaded? (what action)

A

Eccentric action

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108
Q

What does increasing the stretch load do?

A

Increases intensity

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109
Q

What are the components of plymetric exercise?

A

Elasticity and viscoelasticity

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110
Q

What is the ultimate force generator?

A

The sarcomere

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111
Q

What are muscle fibers and cells composed of?

A

Myofibrils

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112
Q

What are repeating subunits of myofibrils known as?

A

Sarcomeres

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113
Q

What are dark bands / A bands?

A

Thick myosin

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114
Q

What are light bands/ I band?

A

Thin actin

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115
Q

What helps keep sarcomeres aligned?

A

Structural proteins, also provide mechanical stability

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116
Q

How do all the structural proteins disperse forces?

A

Longitudinally and laterally

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117
Q

What does the shortening of sarcomeres in unison do?

A

Creates movement

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118
Q

What forms a cross bridge?

A

Each myosin head attaches to an adjacent actin filament

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119
Q

What does the amount of force in a sarcomere depend on?

A

the simultaneously formed cross bridges & the length at any moment

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120
Q

What length gives the greatest possible crossbridges?

A

Resting

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121
Q

What is an action potental?

A

A sum of all competing inhibitory/excitatory inputs

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122
Q

What is rate coding?

A

The rate of sequential activation - smooth increasing muscle force

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123
Q

What happens with smaller sized units?

A

Less force/more fine motor control

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124
Q

What happens with larger units?

A

Larger force and high innervation ratio

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125
Q

What is recruited first? small or large?

A

Smaller recruited before larger

126
Q

What is the rate coding and recruitment of the motor unit specific for?

A

highly specific to demand

127
Q

Which muscle activation requires less units and more cross bridges?

A

Eccentric

128
Q

What do concentric movements require?

A

more motor units for same muscle force

129
Q

What is muscle fatigue?

A

Exercise-induced decline in max voluntary muscle force despite max effort

130
Q

What is the basis of neuromuscular overload and adaptation training?

A

muscle fatigue

131
Q

What reverses muscle fatigue normally?

A

Rest

132
Q

What is rate of fatigue specific to?

A

Task and rest-work cycle

133
Q

What do high intensity short duration activities do in terms of fatigue?

A

Rapid fatigue, recover after a few minutes of rest

134
Q

What does low intensity low duration activity require afterwards?

A

longer rest

135
Q

Are women or men less fatiguable?

A

Women

136
Q

Are older of younger people less fatiguable with isometrics?

A

Older

137
Q

When does DOMS peak?

A

24-72 hours

138
Q

What is a 1RM used for?

A

Quantify strength gains

139
Q

What does strength training do with sarcomeres?

A

Added in parallel

140
Q

When does atrophy occur?

A

Within first few weeks (3-6% in first week)

141
Q

What does immobility do to muscle type?

A

Increase slow twitch

142
Q

What does Excursion do? (jaw)

A

Serves as a pivot point with contralateral condyle making a wider arc of rotation

143
Q

What do protrusion and retrusion do?

A

Follow slope of articular prominence

144
Q

What is depression and elevation of the jaw?

A

combo rotation and translation, axis contantly moving, no set ratio of rot/translation

145
Q

What happens during the early phase (jaw)?

A

35-50% primarily rotation, posterior rotation on concave inferior surface of the disc; mandible goes inferior/posterior

146
Q

What happens during late phase?

A

Final 50-65%, primarily translation, condyle and disc slide forward and inferior along articular eminence

147
Q

What are the primary muscles of mastication?

A

Masseter, temporalis, medial pterygoid, lateral pterygoid

148
Q

What is the neutral zone?

A

The amount of intervertebral movement that occurs with the least passive resistance from the surrounding tissues

149
Q

What increases the neutral zone?

A

Injury or weakness of surrounding tissues

150
Q

What is spinal instability?

A

Loss of intervertebral stiffness that can lead to abnormal and increased interverterbal motion

151
Q

Where can core stability also be viewed from?

A

A segmental or a whole spine level

152
Q

What makes the neutral zone decrease?

A

muscle force

153
Q

What are the sagittal plane kinematics of the neck ?

A

120-130 degrees combined
80 degrees ext
40-50 flex (20-25% total at OA/AA, rest C2- C7)
Medial -lateral axis

154
Q

When is the vertebral canal greatest?

A

Full flexion, least in ext

155
Q

What creates restraint in the neck in flexion?

A

Ligamentum nuchae, interspinous ligaments in flexion, compression forces on anterior margin of AF

156
Q

What creates restraint in the neck in extension?

A

Approximation of apophyseal joints, compression forces on posterior margin of AF

157
Q

What are the arthrokinematics of the AO joint?

A

Occipital condyles roll backwards in ext/ forwards in flexion, slide in opposite direction

158
Q

How much flexion and ext at the AA joint?

A

15 degrees

159
Q

What are the arthrokinematics of C2-C7?

A

Follows plane of facets, overall 90-100 degrees of motion

160
Q

What are the arthrokinematics of extension an C2-C7?

A

Inferior facets slide inferior and posterior 55-60 degrees and load inferior apophyseal joints

161
Q

What are the arthrokinematics of flexion of the c2-c7 joints?

A

Inferior facets slide superiorly and anteriorly, 35-40 degrees, stretches capsule and less joint surface contact

162
Q

What percentage of flexion of the neck do we need to back up while driving?

A

42-48% flexion

163
Q

What degree of flexion on each side do we need to drive?

A

65-75 degrees and 50-60% axial rotation

164
Q

What is the AA designed for?

A

rotation

165
Q

How much rotation each direction at the AA joint?

A

35-40

166
Q

What slides and what is the axis at the AA joint?

A

Atlas slides, axis is dens

167
Q

What does full rotation stretch?

A

Both vertebral arteries

168
Q

What is the movement at C2-C7 guided by?

A

Facets at 45 degrees

169
Q

What is the glide at C2-C7 joints?

A

Inferior glides posteriorly/inferiorly same side, opposite is anterior and superior

170
Q

What are the arthrokinematics of side bending of the neck in the frontal plane?

A

Inferior facets slide inferiorly and slightly postieriorly, lateral flexion side moves superiorly and anteriorly

  • small rolling @ occipital condyles, slide opposite
171
Q

What are the ostrokinematics of elevation of the SC joint?

A

Frontal plane
A-P axis
35-45 degrees elevation
10 degrees degression

172
Q

What are the arthrokinematics of elevation and depression at the sc joint?

A
  • longitudinal diameter
  • elevation: convex surface rolls superiorly and slides inferiorly
  • depression: convex surface rolls inferiorly and slides superiorly
173
Q

Which shoulder joint is not a true joint?

A

ST joint

174
Q

What are the arthrokinematics of abduction and adduction of the shoulder?

A
  • frontal plane, AP axis
  • convex head of humerus rolls superiorly and slides inferiorly along the longitudinal diameter of the fossa, adduction is opposite
175
Q

Why does the large humeral head not roll off?

A

Sliding

176
Q

Where is the ICL stretched? (Shoulder movement)

A

in 90 degrees of abduction

177
Q

What is the ratio of the scapulohumeral rhythum?

A

2:1 - every 3 degrees of abduction: 2 degrees at GH joint/ 1 at ST upward rotation

178
Q

What is the 60 degrees of the scapula during full abduction a result of?

A

Simultaneous elevation of the clavicle at the SC joint combined with upward rotation of the scapula at the AC joint

179
Q

What does the clavicle do during full abduction?

A

Retracts at the Sc joint

180
Q

Where is the clavicle to start?

A

Horizontal about 20 degrees posterior to frontal plane

181
Q

How much does the clavicle retract during abduction?

A

15-20 degrees

182
Q

What does the scapula do with full abduction?

A

Tilts posteriorly and slightly rotates outward

183
Q

What does the postierior tilt and external rotaion of the scapula help with?

A

Keeps scapula flush with the thorax, orients the fossa, moves the coracoacromial arch away from the advancing humeral head

184
Q

How much does the clavicle rotate during full abduction?

A

20-35 degrees

185
Q

What is the most predominant motion of the clavicle with abduction?

A

rotation

186
Q

What does the natural external rotation of the humerus during abduction allow for?

A

the greater tubercle on the humerus to pass posterior to the acromion

187
Q

What are the retractors?

A

middle trap, rhomboids, lower trap

188
Q

What are retractors essential for?

A

Pulling activities

189
Q

What do the retractors do?

A

Anchor scapula to axial skeleton

190
Q

What are the upward rotators of the ST joint essential for?

A

elevation of the UE

191
Q

What do the upward rotators provide?

A

Stable attachments for the more distal mobilizers

192
Q

What are the athrokinematics of abduction at the GH joint regarding the supraspinatus?

A

Supraspinatus rolls the humeral head superiorly toward abduction while also compressing the joint for added stability

193
Q

What muscles do shoulder IR?

A

subscapularis
pec major
lat dorsi
teres major
anterior deltoid

194
Q

What muscles do shoulder ER?

A

Infraspinatus
Teres minor
posterior deltoid

195
Q

What is kinematics?

A

Describes the motion of a body without regard to the forces or torques that may have produced the motion

196
Q

What is kinetics?

A

Describes the forces or toruqes that act on or within a body

197
Q

What muscles activation is used when slowing lowering a book to a table?

A

Eccentric to decelerate the descent of the book

198
Q

What is a force?

A

The magnitude of a push applied against a patients skin

199
Q

What is a pressue?

A

The force divided by the contact area

200
Q

What can a force do when applied to a small surface area?

A

create large and potentially damaging pressure (also called stress)

201
Q

Why does bone heal better than articular cartilage?

A

Bone has blood supply and a well developed periosteum and endosteum

202
Q

Describe two natural effects of aging on connective tissues?

A
  • slower rate of synthesis of fibrous proteins and proteoglycans
  • tendons of muscles become less stiff and unable to quickly and effectively transmit stabilizing forces
203
Q

What is the function of synovial fluid?

A

Provides nutrients to the articular cartilage, act as a lubricant that reduces the coefficient of friction between joint surfaces

204
Q

What happens with a smaller pennation angle?

A

More force able to be generated

205
Q

What tissues are responsible for a muscles passive length-tension curve?

A
  • extracellular connective tissues
  • structural proteins
206
Q

Do myofiliments contract with the muscle?

A

NO, they slide past one another (sliding filament theory)

207
Q

What is tetanization?

A

To sustain a force beyond the twitch duration, the muscle fibers must receive additional action potentials before the muscle force from the previous action potential is lost

208
Q

What does tetanization allow?

A

a muscle fiber to accumulate tension

209
Q

What happens as a muscle starts to fatigue from prolonged submax effort?

A

The EMG from the agonist muscle progressively increases

210
Q

What will the EMG amplitude be for a muscle during eccentric vs concentric

A

eccentric will be less than that for lifting the same load (concentric)

211
Q

How does the nervous system increase muscle force?

A
  • recruitment
  • rate coding
212
Q

What is a motor unit?

A

A single alpha motor neuron and all its innervated muscle fibers

213
Q

What is the Henneman size principle?

A

Motor units are naturally recruited by the nervous system in order of increasing size - smaller before larger

214
Q

What does immobilization increase?

A

fast twitch fibers

215
Q

Adding sarcomeres in parallel increases…

A

Skeletal muscle hypertrophy and contractile force

216
Q

What does adding sarcomeres in seres increase?

A

The speed of contraction of the muscle fiber

217
Q

What is efferent innervation?

A

Nerves traveling from the CNS to a muscle

218
Q

What is afferent innervation?

A

Nerves traveling from the muscle towards the CNS

219
Q

Which variable is most responsible for the magnitude and direction of the joint reaction force at the elbow?

A

Muscle force

220
Q

What is the mass determined by?

A

the number of particles

221
Q

What does the mass moment of interia depend on?

A

Mass and how it is distributed relative to the axis of rotation

222
Q

Where is the COM in the human bodY?

A

Anterior to S1

223
Q

Would a muscle force through the axis of rotation create torque?

A

NO

224
Q

What is a clinical example of Mechanical advantage?

A

MMT

225
Q

What is the arthrology of the HU joint?

A

Contributes to flexion/extension and stability

226
Q

What is the arthrology of the HR joint?

A

Contributes to flexion/ext; is a MODIFIED hinge joint

227
Q

What is excessive cubitus valgus?

A

20-25 degrees

228
Q

What does the elbow capsule incompass?

A

3 joints - HR, HR, prox RU

229
Q

What do the ligaments in the capsule of the elbow provide?

A

Multiplanar stability

230
Q

What can injury to the MCL cause?

A

Compression Fx, ulnar nerve injury, anterior capsule, medial musculature at epicondyle

231
Q

What can cause a NWB MCL injury?

A

Repetitive valgus producing strain, overhead athletes

232
Q

What is tommy john surgery?

A

Repair of the anterior fibers of the UCL through a tendon graft from palmaris longus, gracillis, or plantaris

233
Q

What is a terrible triad injury?

A

FOOSH and supinated
- elbow joint dislocation ( lig injury)
- fx radial head
- fx coronoid process

234
Q

What problems can the terrible triad cause?

A

persistent instability, nerve damage, heterotopic ossification, stiffness

235
Q

What happens during flexion of the elbow? (roll and slide)

A

radius rolls and slides up

236
Q

How many joint capsules are there for the RU, HU, and HR joints?

A

one joint capsule shared

237
Q

What holds the radial head by the ulna?

A

fibro-osseous ring; radial notch and annular ligament

238
Q

What stabalizes the distal RU joint?

A

TFCC, pronator quadratus, ECU tendon, distal oblique fibers interosseous membrane

239
Q

What do the radius and carpal bones do during rotation?

A

Rotate around the fixed humerus and ulna

240
Q

What happens proximally do the raidus during supination?

A

rotation of the radial head in the fibro-osseous ring

241
Q

What happens distally to the radius during supination?

A

Radius rolls and slides the same way - articular discs proximal surface slides across ulnar head

242
Q

What do the radius and carpal bones do during prontation?

A

Rotate around the fixed humerus and ulna

243
Q

What does the proximal surface of the disc do during pronation?

A

Slides across the ulnar head

244
Q

What does the HR joint do during pronation?

A

The fovea of the radial head spins against the capitulum

245
Q

What muscles do supination?

A

Biceps brachii, supinator

246
Q

What bones are in the proximal row of carpals?

A

scaphoid, lunate, triquetrum, pisiform

247
Q

What bones are in the distal row of carpals?

A

Trapezium, trapezoid, capitate and hamate

248
Q

What is the arthrology of the RC joint?

A

Concave radius and disc and convex scaphoid and lunate

249
Q

What is the arthrology at the Midcarpal joint?

A

Between proximal and distal rows, continuous capsule

250
Q

How many joints make up the midcarpal joint?

A

13

251
Q

How many degrees of freedom at the wrist?

A

2 - flx/ext, u/r dev

252
Q

Where is the axis of the wrist?

A

Through the head of the capitate

253
Q

What directs the osteokinematics of the entire hand?

A

the rotation of the capitate

254
Q

What occurs with radial deviation?

A

Extension

255
Q

What are the central columns of the wrist formed by?

A

Linkages between radius and lunate, medial compartment of midcarpal joint

256
Q

What are the roll and slide during extension of the wrist?

A
  • Convex lunate rolls dorsally and slides in a palmar directon
  • head of capitate rolls dorsally on lunate and slides in a palmar direction
257
Q

What is carpal instability?

A

Excessive mobility between carpals, usually laxity or ruptured ligaments

  • can be static or dyamic
258
Q

What is the rotational collapse of the wrist?

A

Mechanically proximal carpals are a row of mobile bone between two relative rigid segments; collapse due to compression

259
Q

What is the most frequently dislocated carpal bone?

A

Lunate

260
Q

When is activation of the wrist extensors necessary?

A

To block the wrist flexion caused by the activated finger flexor muscles

261
Q

When does maximal grip force occur?

A

At about 30 degrees of extension

262
Q

What are the kinematics of the abduction/adduction of the CMC joint?

A

Convex surface of the thumb metacarpal is moving on fixed concave trapezium - rolls palmar and slides dorsally

263
Q

What are the kinematics of the flexion/ext of the CMC joint of the thumb?

A

Concave metacarpal on convex trapezium - flexion: metacarpal rolls and slides in ulnar direction
- extension: slide/glide in lateral direction

264
Q

What happens with the opposition of the CMC thumb?

A

full opposition is closed packed position

265
Q

What are the general features of the MCP joints?

A

Ovoid convex head of metacarpals and shallow concave proximal phalanges

266
Q

Where do the collateral ligaments attach?

A

Proximal attachment at tubercle, cord part (thick and strong)

267
Q

What are the volar plates?

A

Dense, thick, fibrocartilage; runs base of proximal phalnx; thinner elastic portion to MC

268
Q

What are the fibrous digital sheaths?

A

Form tunnels or pulleys for extrinsic finger flexors are anchored on plates

269
Q

What are the kinematics of the DIP and PIP?

A

Concave base rolls and slides in the palmar direction

270
Q

What does the radial nerve innervate? (generally)

A

Extensive extensor muscles

271
Q

What does the median nerve innervate? (generally)

A

Most of the extrinsic flexors

272
Q

What does the ulnar nerve innervate?

A

medial half of FDP, hypothenar muscles

273
Q

Where are the flexor pulleys?

A

Embedded within the fibrous digital sheath

274
Q

How many pulleys are there for each finger?

A

5 annular pulleys

275
Q

Where are the major pulleys?

A

At A2 and A4 attached to the shafts (mid and prox)

276
Q

Where are the minor pulleys?

A

A1, 3, 5, attached to palmar plates

277
Q

Where/What are the cruciate pulleys?

A

C1-3 thin crisscross over tendons where digital sheaths bend during flexion

278
Q

What happens without the flexor pulleys?

A

Get ‘bowstring’; A2 A4 reduce torque significantly if injured

279
Q

What percentage of climbers have pulley injuries?

A

20%

280
Q

What must act to prevent MCP and wrist flexion?

A

FDS PIP flexion requires ext; extensor digitorum must act

281
Q

What are tendons connected by in the hand?

A

Juncturae tendinae - stabilize the angle of approach

282
Q

What is the extensor mechanism?

A

Primary distal attachment of ED, EDM, EI and most intrisics

283
Q

What does the extensor mechanism allow for?

A

Allows the extensor force to transfer distally throughout the entire finger

284
Q

What is the dorsal hood?

A

Thin aponeurosis perpendicular to tendon, stabilizes the tendon at the MCP, slings around the proximal phalanx, assists ED in extending the MCP joint

285
Q

What do the lumbricals and interossei attach to? What do they do?

A

The hood, assist ED with extension of PIP and DIP

286
Q

What does the isolated ED get the MCP to do?

A

Ext, but needs intrinsics to get PIP and DIP ext

287
Q

EPL and APL are radial deviators at wrist - so during thumb extension _______ _________ muscles must be activated to stabilize the wrist against unwanted radial deviation

A

Ulnar deviator

288
Q

How many intrinsic muscles of the hand are there?

A

20

289
Q

Lumbricals are …

A

4 slender muscles off tendons of FDP
2 lateral, 2 medial

290
Q

What do the lumbricals do?

A

Flexion at MCP, extension at PIP and DIP

291
Q

Lumbricals have …. muscle spindles

A

high levels

292
Q

What do the palmar interossei do?

A

Adduct

293
Q

What do the dorsal interossei do?

A

Abduct

294
Q

What happens with grip with a ulnar nerve injury?

A

38% reduction in max grip effort

295
Q

What happens if wrist extensors are paralyzed?

A

Wrist flexion not neutralized and tendons overstretched in ED

296
Q

What does the broad triangular medial collateral ligament of the elbow allow for?

A

Fibers to pass anterior and posterior to the ML axis of rotation of the elbow

297
Q

What are the arthrokinematics at the HR joint during elbow flexion and supination?

A

Combined spin and a roll and slide in similar directons

298
Q

How many nerves innervate the primary muscles that flex the elbow?

A

three - musculocutaneous, radial, median

299
Q

What does the deltoid do during a pushing action?

A

Flexes shoulder, produces a shoulder flexion torque that neutralizes the shoulder extension torque potential of the long head of the triceps

300
Q

What muscle is the antagonist of the brachialis?

A

Medial head of triceps

301
Q

What happens during flexion at the RC joint?

A

Proximal carpal bones roll palmarly and slide dorsally; capitate rolls palmar direction and slides dorsally

302
Q

What happens during extension at the RC joint?

A

The proximal row of carpal bones rolls dorsally and slides in a palmar direction

303
Q

Which muscle is the most direct antagonist to the FCU?

A

Extensor pollicis longus or extensor carpi radialis brevis

304
Q

What happens with flexion of the wrist?

A

Ulnar deviation

305
Q

What muscles attach at the lateral epicondyle of the humerus?

A

Brachioradialis
ECRB
ECBL
ECU
ED
anconeus
supinator

  • all innervated by radial nerve
306
Q

What happens with the FCU and the FCR during active flexion of the wrist?

A

Both produce flexion, but each muscle neutralizes the others frontal plane actions

307
Q

What does ulnar neuropathy cause?

A

Atrophy in the hypothenar eminence, the interosseous spaces, and the web space of the thumb

308
Q

What does median neuropathy cause?

A

atrophy in the thenar eminence

309
Q

What is the opposition of the thumb a combination of?

A

Abduction and flexion

310
Q

What ligaments help prevent a valgus elbow?

A

The MCL of the elbow

Biomechanics final review (1 decks)

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