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Flashcards in Chapter 2 Deck (42):
1

Biomechanics

focuses on the mechanisms through which the musculoskeletal components interact to create movement

2

Origin

proximal attachment (toward center of body)
-attached to stationary structure

3

Insertion

distal attachment (away from center of the body)
-attached to mobile structure

4

Fleshy attachements

muscle fibers directly attached to bone over a wide area so force is distributed rather than localized.
-most often found at proximal end of a muscle

5

Fibrous attachments

i.e. tendons
blend into and are continuous with both the muscle sheaths and the connective tissue surrounding the bone.

6

Agonist

muscle that brings about movement

7

Antagonist

muscle that can slow down or stop movement
-assist in joint stabilization

8

Cartilaginous joint

joints connected by cartilage

9

Synergist

a muscle that assists indirectly in a movement
-ex. muscles that stabilize scapula act as synergists during upper body arm movement

10

First-class lever

lever for which the muscle force and resistive force act on opposite sides of the fulcrum

11

Fulcrum

pivot point of a lever

12

Lever

rigid or semirigid body that, when subjected to a force whose line of action does not pass through its pivot point, exerts force on any object impeding its tendency to roate

13

Mechanical Advantage

ratio of moment arm through which an applied force acts to that through which a resistive force acts.

14

Moment arm

perpendicular distance from the line of action of the force to the fulcrum.
-aka force arm, lever arm, or torque arm

15

Line of Action

infinitely long line passing through the point of application of the force, oriented in the direction in which the force is exerted.

16

Muscle Force

force generated by biomechanical activity, or the stretching on non-contractile tissue, that tends to draw the opposite ends of a muscle toward each other

17

Resistive Force

force generated by a source external to the body (gravity, inertia, friction) that acts contrary to muscle force

18

Second-class lever

lever for which the muscle force and resistive force act on the same side of the fulcrum, which the muscle force acting through a moment arm longer than that through which the resistive force acts
-i.e. calves raising the body onto the balls of the feet

19

Third-class lever

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 shorter than that through which the resistive force acts

20

Torque

degree to which a force tends to rotate an object about a specified fulcrum.
-defined quantitatively bas the magnitude of force x length of its moment arm.
aka moment

21

Anatomical position

body erect
arms down at sides
palm forward

22

Sagital plane

left right

23

Frontal plane

front back

24

Transverse plane

top bottom

25

Strength

ability to exert force

26

Acceleration

change in velocity per unit time

27

Power

time rate of doing work
-Power = Work / Time

28

Work

product of force exerted on an object and the distance the object moves in the direction in which the force is exerted
-Work = Force x Displacement

29

Weight to equal Newtons

N = pounds x 4.448
N = kg mass x 9.8 m/s2 (gravity)
N = kg force x 9.807

30

Angular Displacement

angle through which an object rotates
-measured by radians (rad)

31

Angular Velocity

object's rotational speed
-measured in rad/s

32

Rotational work equation

Work = torque x angular displacement

33

Rotational power equation

Power = Work / Time (same are power eq.)

34

Recruitment

recruiting motor units during muscle contraction

35

Rating Coding

rate at which motor units are fired

36

Muscle force is greater when:

More motor units are involved in a contraction.
Motor units are greater in size.
Rate of firing is faster.

37

Pennate Muscle

fibers that align obliquely with the tendon
-featherlike arrangement

38

Angle of Pennation

angle between muscle's origin and insertion
-0 degrees corresponds to no pennation

39

Concentric Muscle Action

muscle shortens bc contractile force is greater than the resistive force.
-forces generated within the muscle and acting to shorten it are greater than the external forces acting at its tendons to stretch it

40

Eccentric Muscle Action

muscle lengthens bc contractile force is less than the resistive force.
-forces generated within muscle and acting to shorten it are less than the external forces acting at its tendons to stretch it (increases risk of soreness/injury)

41

Isometric Muscle Action

muscle length does not change, bc contractile force is equal to resistive force.
-force generated within in the muscle and acting to shorten it are equal to the external forces acting at its tendons to stretch it

42

Classic Formula

load lifted / body weight^2/3