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Biomechanics > 3 > Flashcards

3 Flashcards

1
Q

Meyerhold’s theory

A

N=A1+A2

actor = moving/material + thinking /organizing of material

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2
Q

Static work

what is it and what kind of contraction

A

no mechanical work performed
posture/joint position maintain
isometric contraction - muscle tension is equal to external load with muscle length constant

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3
Q

Dynamic work

A

mechanical work performed
posture/joint position changes
Concentric contraction - muscle tension is at least equal too external load with muscle shortening
Eccentric contraction - muscle tension is equal to external load with muscle lengthening (equal to/less than)

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4
Q

Concentric and eccentric contraction make (2)

A

Isokinetic contraction - constant joint velocity (variable load) that requires maximum force
using a dynomometer which changes the load depending on how much you put in (maximum voluntary contraction

Isoinertial contraction - constant resistance (variable velocity) for submaximal muscle force production

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5
Q

tendons
connect?
made of?

A

connect muscles to bones
fibrous tissue entwine with periosteum (outer bone) - extension of fascia
Periosteum - tendon - surface fascia of muscle

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6
Q

Fascia

A

fibrous connective tissue that surrounds and seperates individual muscles

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7
Q

Fasiculus

A

bundle of muscle fibres

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8
Q

Muscle fibre

A

single complete full length muscle cell of multiple nuclei and motor end plates

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9
Q

Myofibril

A

delicate strand that makes one muscle fibre.

has contractile elements and striations

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10
Q

sarcoplasm

A

cytoplasm in muscle

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11
Q

sarcomere

A

repeated section in myofibril between z lines

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12
Q

sarcolemma

A

cell membrane

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13
Q

i band (2)

A

only actin

bysected by z line

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14
Q

When the muscle is relaxed

A

open space

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15
Q

when the muscle is contracted

A

loss of center space

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16
Q

thick bands

A

myosin - h zone

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17
Q

thin bands

A

actin

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18
Q

a band

A

both myosin and actin

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19
Q

how does cross bridge from

A

troponin pulls tropomyosin off the actin

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20
Q

z line (3)

A

anchor point for actin filaments
connection point for sarcomere packages
define limit of sarcomere

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21
Q

M line

A

centre f myosin filaments

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22
Q

motor nerve

A

multiple motor axons to the same area

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23
Q

motor unit

A

single motor axon and all the muslce fibre it innervates

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24
Q

motor endplate

A

junction between axon and sarcolemma (terminal nerve branches)

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25
Q

Huxley’s sliding filament theory - 11 steps

A
  1. ap travels in on motor axon
  2. ap createds end plate potential
  3. epp depolarize sarcolemma
  4. depolarization of sarcolemma opens transverse tubules
  5. ca release
    6 ca bind to troponin on actin filament
  6. troponin and tropomyosin change shape, receptor sites exposed
  7. actin receptor binds with myosin apt cross bridge
  8. actin activates atp, adp and phosphate removed, energy released
  9. energy release causes power stroke of cross-bridge, thin over thick
  10. new ATP binds to cross bridge, breaking actin myosin bond
    IF NOT - no breaking bond and RIGOR MORTIS
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26
Q

last four steps of the sliding filament theory will repeat as long as

A

Ca is in system (muscle activation)

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27
Q

3 Biomechanical spinoffs of the sliding filament theory

A

force length relationship
length tension relationship
positional insufficiency

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28
Q

force length relationship

3 scenarios

A

sarcomere length and difficulty of contraction
small - centre space already used up
medium - space and lots of cross bridge
large - lots of space but not enough crossbridging so no force production

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29
Q

Length tension relationship

3

A

active tension and passive tension - total tension
right around resting length is when tension is produced by sliding filament theory.
increasing passive tension is produced by muscle elasticity, lose active tension but capitalize for muslce for contraction - tensile properties for muscles

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30
Q

positional insufficiency

A

position gives not max force production

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31
Q

muscle vector components (3)

A

rotary, stabilizing, dislocating components

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32
Q

Relationship between A1 and A2

A

(motor commands and efferent copy feeds proprioceptive info (visual and vestibular also) to thinking

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33
Q

granulation to cartilage to bone

A

strength (weight bearing) goes up
stiffness goes up
ultimate strain (how much it takes before it breaks) goes down - different things in place to do different things

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34
Q

Modelling of bone

A

process of bone development from immature to mature

osteoblast from new bone

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35
Q

remodelling of bone

A

process of bone repair and maintenance
osteoblast forms new bone
osteoclast resorb old bone and repurpose Ca

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36
Q

what turns osteoblast on

A

load of material/ stress

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37
Q

what turns osteoclast on

A

not stressed bone

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38
Q

wolff’s law

A

1892 - modelling/remodelling of bone is influenced by mechanical stressed

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39
Q

anisotropy of bone
stress vs strain
points and regions

A

at different orientations you have different yielding points
stress as pressure on material to cause deformity and strain as change of change
elastic region to yield point to plastic region to ultimate strain

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40
Q

plastic region

A

change in material property for permanent alteration and deformation

41
Q

long bone and stress

A

lots but the final bit is ultimate

42
Q

loading that fractures bones

A

combination of bending, torsion and compression

43
Q

3 point bending fracture

A

boot top fracture
top of leg falling forward, ski boot stationary but going forward, resistance at boot top which creates a torsion
beyond yield point reactive force at ground and top of long bone, counter force in the middle

44
Q

torsion

3

A

rotating opposite ends at opposite directions

can be horizontal, vertical, or shear forces that make spiral or torsional fractures

tension is along the plane of shear (instantaneous) high speed torsion can be drastic

45
Q

4 steps of recovery of a bone fracture

A

blood escapes from ruptures blood vessels and form a hematoma

spongy bone forms near developing blood vessels, fibrocartilage forms in more distant regions

fibrocartilage replaced by boney callus

osteoclasts remove excess bony tissue/making new bone structure much like original

46
Q

How to develop spongy bone in a gap

A

workable gap to develop spongy bone
perturbations will stop the advancement
too small and it will never heal because new material is never loaded - load transferred from side to side and therefore resorbed therefore you dont get a boney callus

47
Q

young vs old bone

A

compact vs spongy

48
Q

normal and immobilized bone vs load

A

normal bone can take more before bone integrity is compromised, and immobilized can take less because you lose bone strength by not loading it

49
Q

narrow dynamic compression plate

A

organize the gap activity
changes load distribution of bone
shared force between plate and bone - rigid plate + surface of endosteal reabsorption = increased cortical porosity because osteoclast thinks we do not need as much material

50
Q

possible solution to plate

A

bio dissociate plate

51
Q

epileptic patients and bone recovery (3)

A

decreased bone content because antiepileptics cause vit D deficiency
seizures can disrupt bone remodelling
tonic muscle contractions cause irregular loading

52
Q

does highly loaded bone mean accelerated loading/ roboust development?

A

G.A ilizarov came up with the idea of external fixation with horizontal wire through leg (compressed unions with movable rods) - loads bony callous - actively immobilized - pulls it apart so callus doesnt get resorbed

53
Q

what promotes osteoblast activity

A

Increased calcium and loading for bone deposition

54
Q

Total hip replacement started in _______ by _______________

A

1950 by Charnley

55
Q

Parallel advances between total joint replacement and gait analysis

A

hip - charnley movements - sutherland
knee - gunston Forces - Inman
Gait analysis enabled joint placement by providing functional assessment design/redesign criteria

56
Q

unassembled total hip

A

hip implant, femoral head, polythylene liner, acetabular shell

57
Q

Why do they need lots of revision surgeries?

A

wear at the bearing surface (plastic cup)

loosening of metallic femoral head

58
Q

Risks of total hip replacement in younger patients

A

fracture of femoral stem
lifetime loosening of fixation
a lot needs second injuries

59
Q

most stress on the hip replacement

A

stress on bottom of femoral implant and femoral head and this causes the osteoclast to resorb bony tissue and the bone thins
implant takes more of the loading of the medial aspect often resorbs due to unloading

60
Q

pros and cons if the hip replacement is thinner (4)

A

more elastic, better load transfer, easier to fracture, smaller surface for weight bearing

61
Q

pros and cons if the hip replacement is thicker (4)

A

less elastic
little load transfer
resistant to fractures
larger surfaces for weight bearing

62
Q

improved design of the hip replacement

A

better load transfer
fins limit rotation and promote bony growth
better biological behaviour

63
Q

solving the THR design conundrum - clinical biomechanics

A

moments and counter moments overload tissues at pivot point

force plates to assess loading on the ground

64
Q

Solving the THR design conundrum - experimental biomechanics

A

Gluteus maximus/abductor distance is small

strain gauges fro medial and lateral side of loading/biological loading of real femur to keep bone healthy

65
Q

total force = 0 at the hip how?

A

-gluteus maximus - bodyweight +fsupportof hip

66
Q

longer femur

A

more loading

67
Q

safe phases of gait

A

pre initiation
Double limb support?
post termination

68
Q

3 componenets of gait

A

bones - stable multisegment structure
muscles - energy transfer system
sensory motor closed loop control system

69
Q

power if paradox

A

exercise’s promise for rural and urban canadians living with pd

70
Q

historical research with pd

A

deficit and what neurological foundation makes them exist?
retrospective
theoretical
important but inaccessible to patients

71
Q

PD

A

chronic and progressive motor (resting tremor, stiffness and rigidity, slowness of movement, gait and balance problem as legs do not move with will, 70% fall every year) and non-motor (apatheric, depressed) disorder because of the lack of dopamine in basal ganglia

72
Q

New research with pd

A

persistent skills and what that indicates of their neuromechanical potential - accessible and important as it capitalizes applied theory perspective
biopsychosocial benefits and overcome biopsychsocial barriers

73
Q

paradoxical kinesias

A

surprised movements that use tricks to powerful rehab, so they’re enjoyable and functional therapeutic exercises and ADL
can be aroused from negative or positive emotional arousal

74
Q

Why is there low levels of PA support

A

low levels of support due to lack of experience/comfort of health care professionals, more than 90% had little or no info about the benefits of PA

75
Q

age of PD

A

10% is younger than 50 years

doesnt just happen to old people and doesnt make you old

76
Q

Why isolation and stress of PD patients

A

three years between symptoms and diagnosis of PD with GPs and and neurologists and limited support

77
Q

muscle activation increases

A

after activity

78
Q

sensorimotor enhancement could be from

A 
(cues to move) 
- sound 
- visual 
- proprioception 
- smell 
which activates neurological networks underneath
79
Q

phase 1 of experiments

A

preliminary and feasibility

80
Q

phase 2 of experiments

A

futuristic - intervention such as skating training and technical

81
Q

2 experimental studies

A

motion tracking skates

music and walking dual task

82
Q

to increase balance one could (4)

A

bigger base of support, lower centre of mass, further into perturbation so CoM has bigger distance to travel
internal resistance

83
Q

centre of pressure

A

at the bottom between ground and body

84
Q

6 components to balance

A 
bones 
muscles 
sensorimotor system 
proprioceptive
visual 
vestibular
85
Q

mean elliptical sway area

A

measure of magnitude of balance, decrease in older adults after fitball training

86
Q

peak plate velocity

A

measure of rate of balance. decrease in older adults after fitball training

87
Q

to isolate a component

A

take different components away

  • blind/manipulate vision
  • manipulate proprioception
  • presence of sound
88
Q

PD patient balance with only vision

A

2 central points of balance - mediolateral

89
Q

What and persistant skills bring psychosocial advantages

A

supported in community health and rec settings

90
Q

osteoperosis

A

large holes/gaps in bone matrix

think cortical bones with thin trabeculae

91
Q

osteoarthritis

A 
worn cartilage 
rough weight bearing surface 
narrow joint space 
denatured bone at bone cartilage interface 
damage along weight bearing surface
92
Q

metal stem of hip replacement

A

weight bearing against plastic cup which is glued to the socket and the stem is hammered into the long bone

93
Q

Gunsten knee replacement

A

metal stem bearing against plastic cup
stem into distal bone
cup glued to proximal long bone

94
Q

acetabular shell of total hip replacement

A

low friction

screw holds it in place

95
Q

second generation of acetabular shell

A

with more cement

96
Q

elastic mismatch

A

rigid stem but biological and flexible femur

97
Q

increased calcium

A

increased osteoblast activity and bone deposition

98
Q

stress shielding

A

implant takes more of the loading along medial aspect

99
Q

2 components to maintaining balance

A

projection of center of mass and correction afterwards

Biomechanics (10 decks)

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