Ch. 4 - Biomechanics Flashcards
0
Q
How do muscles transmit force to the environment?
A
Muscles do not act directly to exert force on ground or other objects
They function by pulling against bones that rotate about joints and transmit force through the skin to the environment
1
Q
Musculoskeletal system consists of …. and is configured to…
A
bones, joints, muscles, and tendons
allow variety of movements
2
Q
How many bones in the human body?
A
approx 206
3
Q
function of skeleton
A
provides leverage, support and protection
4
Q
portions of the skeleton
A
axial skeleton and appendicular skeleton
5
Q
axial skeleton components (4)
A
consists of skull (cranium), vertebral column, ribs, and sternum
6
Q
appendicular skeleton components (8 groups)
A
shoulder (pectoral) girdle, bones of arms, wrist, and hands, pelvic girdle, and bones of legs, ankles, and feet
7
Q
joints definition
A
junctions of bones
8
Q
3 types of joints
A
fibrous joints
cartilaginous joints
synovial joints
9
Q
fibrous joints
A
virtually NO movement
ex. sutures in skull
10
Q
cartilaginous joints
A
allow little movement
ex. intervertebral discs
11
Q
synovial joints
A
considerable movement
ex. elbow and knee
12
Q
important features of synovial joints
A
low friction and large ROM
13
Q
sport and exercise movements mainly occur about which type of joint?
A
synovial joints
14
Q
how are joints characterized?
A
by # of directions about which rotation can occur
15
Q
categories of joints (3)
A
uniaxial joints
biaxial joints
multiaxial joints
16
Q
uniaxial joints
A
operate as hinges
rotate about ONE axis
ex. elbow joint (NOT knee joint)
17
Q
is the knee joint a uniaxial joint?
A
NO
18
Q
biaxial joints
A
allow movement about 2 PERPENDICULAR AXES
ex. ankle and wrist
19
Q
multiaxial joints
A
allow movement about ALL 3 perpendicular axes that define space
ex. shoulder and hip ball + socket joints
20
Q
vertebral column components
A
7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 sacral vertebrae 3-5 coccygeal vertebrae
21
Q
cervical vertebrae
A
7
neck region
22
Q
thoracic vertebrae
A
12
middle-upper back
23
Q
lumbar vertebrae
A
5
lower back
24
sacral vertebrae
5
fused together
make up rear part of pelvis
25
coccygeal vertebrae
3-5
"vestigal internal tail"
extending down from pelvis
26
skeletal musculature
system of muscles that enables the skeleton to move
27
origin and insertion
skeletal muscle attached to bone with connective tissue
origin = proximal attachment
insertion = distal attachment
28
origin
proximal attachment
29
insertion
distal attachment
30
fleshy attachments
muscle fibers directly attached to the bone
usually over wide area so force is distributed rather than localized
most often found at proximal end of muscle
31
where are fleshy attachments most often found?
proximal end of muscle
32
are fleshy attachments usually localized or over a wide area?
wide area
33
fibrous attachments
blend into and are continuous with both the muscle sheaths and the connective tissue surrounding the bone
additional fibers that extend into the bone itself for strong union
ex tendons
34
agonist
muscle most directly involved in bringing about a movement
| aka prime mover
35
agonist aka
prime mover
36
antagonist
muscle that can slow down or stop the movement
| assists in joint stability and in braking the limb toward end of fast movement
37
antagonist portects...
"gamentous and cartilaginous" joint structures from potentially destructive forces
38
triceps and biceps during baseball throw is an example of...
triceps agonist and biceps antagonist
| during baseball throw (fast movement) biceps work to slow the arm and protect from destructive forces
39
synergist
muscle assisting indirectly in movement
| ex. muscles stabilizing the scapula are synergists in arm movement
40
synergists are required to control body motion when...
the agonist is a muscle that crosses 2 joints (ex. rectus femoris flexes hips and extends knee with contraction)
so, ex. synergist would be gluteus maximus counteracting hip flexion during rectus femoris facilitated knee extension for upward movement of squat
41
synergist for upward movement of squat
gluteus maximus
42
body movements in sports/exercise act through...
bony levers of the skeleton
43
lever (def)
rigid/ simerigid body that, when subjected to a force whose line of action does not pass through its pivot point, exerts force on an object impeding its tendency to rotate
44
fulcrum (def)
pivot point of a lever
45
moment arm (def)
perpendicular distance from the line of action of the force to the fulcrum
46
torque aka
moment
47
torque (def)
degree to which a force tends to rotate an object about a specified fulcrum.
defined quantitatively as the magnitude of a force x the length of its moment arm
48
SI unit for torque
Nm
49
Torque (quantitatively)
force x moment arm
50
muscle force (def)
force generated by biomechanical activity, or the stretching of noncontractile tissue, that tends to draw the opposite ends of muscle toward eachother
51
resistive force (def)
force generated by a source external to the body that acts contrary to muscle force
ex. gravity, inertia, friction
52
mechanical advantage (def)
ratio of moment arm through which applied force acts to that through which a resistive force acts
mech. adv. = Mm/Mr (M=moment arm)
53
mech. adv. > 1
allows the applied (muscle force) to be less than the resistive force to produce an equal amount of torque
54
mech. adv. < 1
disadvantage, applied force must be greater to be equal to resistive force
55
patella in terms of mech. adv.
patella increases mech. adv. of quads by increasing moment arm
absence of patella allows tendon to fall closer to the knee's center of rotation
56
first class lever
a lever for which the muscle force and resistive force act on OPPOSITE sides of the fulcrum
ex. elbow extension/triceps extension
57
EFR
first class lever
58
mech adv first class lever
<1
59
Lever that resembles a teeter totter
```
1st class lever
EFR
```
60
second class lever
a lever for which the muscle force and resistive force act on the SAME side of the fulcrum, with the muscle force acting through a moment arm LONGER than that of the resistive force
ex. calf muscles work to raise body onto balls of feet (plantatflexion)
61
FRE
second class lever
62
mech adv second class lever
> 1
63
Lever that resembles a wheel barrow
```
second class lever
FRE
```
64
third class lever
a lever for which the muscle force and the resistive force act on the SAME side of the fulcrum, with the muscle force acting through a moment arm SHORTER than that of the resistive force
ex. elbow flexion
65
FER
third class lever
F____^E_____vR
66
mech adv of third class lever
< 1
67
lever that resembles a shovel
third class lever
68
most human muscles rotate the limbs about body joints that operate at .... mech adv
< 1 or mechanical disadvantage
69
during sports/PA, forces in muscles and tendons are....
MUCH HIGHER than those exerted by the hands or feet on external objects or the ground
70
a person whose tendons are inserted on the bone further from the joint center should be able to lift .... weights because ....
able to lift HEAVIER weights
| because muscles force acts through a longer moment arm and thus can produce greater torque around the joint
71
variation in tendon insertion -- mech adv of insertion farther from joint center is accompanied by... because...
LOSS OF MAX SPEED
because as the tendon is inserted farther from the joint center, the muscle has to contract more to make the jiont move through a given ROM
72
To produce a given joint rotational velocity, a muscle inserted farther from the joint center must contract at a ... speed, at which it can generate ... force due to the .... relationship of muscles
contract at a HIGHER SPEED
can generate LESS force
due to INVERSE FORCE-VELOCITY relationship
73
tendon insertion farther from joint than normal is advantageous for?
disadvantageous for?
slow movements such as power lifting
disadvantageous for athletic activities at HIGH SPEEDS such as tennis
74
anatomical planes of the human body
sagittal plane - L/R
frontal plane - front/back
transverse plane - upper/lower
75
sagittal plane and ex
L/R
| ex. standing barbell curl
76
frontal plane and ex
front/back
| ex. standing lateral dumbbell raise
77
transverse plane and ex
upper/lower
| ex. dumbbell fly
78
as weight is lifted, the moment arm (MR) changes with the horiz distance from the weight to the elbow.
how does this relate?
think ideal angle of elbow to manage weight due to mech adv.
79
strength (def)
ability to exert force.
80
how to measure strength? (controversy)
the weight that a person can lift is the oldest quantitative measure
isometric strength testing and isokinetic strength testing are more recent measurements
81
acceleration (def)
change in velocity per unit time
82
resistive force (Def)
force = (mass)x(acceleration)
83
Strength (Knuttgen and Kraemer)
the maximal force that a muscle or muscle group can generate at a specified velocity
THIS DEF IS MORE MEANIGFULLY RELATED TO SPORT ABILITY THAN ARE STATIC MEASURES
84
what def of strength is more meaningful for sport ability than static measures?
Knuttgen and kraemer: "the max force that a muscle or muscle group can generate at a specific velocity"
(must control for velocity during strength training)
85
controlling and monitoring velocity during strength training requires... but
sophisticated equipment
| but there are more meaningful strength scores than static strength measures or maximum loads lifted
86
Power (def)
the time rate of doing work
```
Work = force x distance
POWER = WORK/TIME
```
87
WORK =
FORCE x DISTANCE
88
SI unit for forocoe
N
89
SI unit for distance
meter
90
SI unit for time
seconds
91
SI unit for work
Joule or Nm
| note: convert kg --> N
92
volume of work =
(force)(distance)(reps)
93
distance component of work refers to...
distance moved along the line of action of the force
94
SI unit for power
watt (W)
| J/s
95
weight SI unit
includes acceleration by gravity (m/s^2)
| if local g is not available, 9.8 m/s^2 is approximate
96
weight=
(mass)(acceleration of gravity)
97
angular displacement (def)
the angle through which an object rotates
98
SI unit for angular displacement
radian (rad)
99
1 radian =
180/pi = 57.3deg
100
angular velocity (def)
object's rotational speed
101
SI unit for angular velocity
rad/s
102
distance component of the torque unit refers to...
length of the moment arm (perpendicular to line of action of force)
103
SI unit for torque
Nm or joules (J)
104
work done in rotating an object is measured in...
J (joules)
105
rotational work =
torque x angular displacement
106
rotational power
work / time
107
SI unit for rotational power
watts
108
although strength is often associated with ... speeds and the word power with .... speeds of movement, both variables reflect...
strength - slow speed of movement
power - high speed of movement
both variables reflect the ability to exert force at a given speed
109
difference between strength and power
strength - capcity to exert force at any given speed
| power is mathematical product of force and velocity at whatever speed
110
CRITICAL: the ability to exert force at speeds characteristic of a given sport to overcome gravity and accelerate the body or an implement
ex...
O Line and D Line exert force/power at slow speed
badmitton/tennis player exerts force/power at high speed
111
biomechanical factors in human strength include... (8)
```
neural control
muscle cross-sectional area
muscle fiber arrangement
muscles length
joint angle
muscle contraction velocity
joint angular velocity
body size
```
112
neural control affects maximal force output of a muscle by...
recruitment and rate coding
113
recruitment
neural control
| determining which and how many motor units are involved in a muscle contraction
114
rate coding
neural control
| the rate at which the motor units are fired
115
force is greater when (regarding neural control)
more motor units are involved in contraction
motor units are greater in size
the rate of firing is faster
116
much of improvement in strength in the first few wks of RT is attributable to...
neural adaptations, where brain learns how to generate more force from a given amount of contractile tissue
117
improvements in strength after first few wks of is through (slower or faster) mechanisms than neural adaptations?
slower
118
muscle cross-sectional area
force a muscle can exert is related to its cross-sectional area rather than its volume
