Midterm Part 2 Muscle types, action, function, and mechanical levers

Question 1

How many skeletal muscles are there? how much our body weight?

Answer 1

over 600.

40-50%

Question 2

Definition: muscles work in groups rather than independently to achieve a given joint motion

Answer 2

aggregate muscle action

Question 3

diff shapes and fiber arrangements affect a muscle’s ability to exert…

Answer 3

force.

Question 4

diff shapes and fiber arrangements affect the ____ through which a muscle can effectively exert _____ onto a bone.

Answer 4

diff shapes and fiber arrangements affect the range through which a muscle can effectively exert force onto a bone.

Question 5

greater cross section diameter of muscle means…

Answer 5

greater force

Question 6

longer muscles can shorter through a greater range and are more effective at what?

Answer 6

moving joints through large ranges of motion.

Question 7

What are the five fiber arrangements?

Answer 7

parallel, fusiform, pennate, convergent, circular

Question 8

Parallel muscles fiber arrangement?

Answer 8

arranged parallel to length of muscle (sartorius). - produce greater range of movement than similar sized muscle w pennate arrangement.

Question 9

Fusiform muscles fiber arrangement?

Answer 9

spindle. parallel. w large cross section diameter.
produce greater range of movement than similar sized muscle w pennate arrangement.

ex. biceps brachii

Question 10

Pennate muscles fiber arrangement?

Answer 10

feather-like. shorter fibers. obliquely to tendons like a feather. increases cross sectional area of muscle, increasing POWER (tension).

uni, bi, multi

Question 11

Pennate Muscles: uni, bi, multi?

deltoid?
extensor digitorum?
rectus femoris?

Answer 11

deltoid - multi
ext - uni
rectus - bi

Question 12

convergent fiber arrangement?

Answer 12

broad origin, pointed insertion. versatile w direction of pull.

ex. pec major

Question 13

Circular muscles fiber arrangement?

Answer 13

derr

sphincter, orbicularis oris

Question 14

Strength definition

Answer 14

max force a muscle can generate for a single max effort.

amt of tension muscle produces.

Question 15

power definition

Answer 15

work done over a given period of time (work/time)

Question 16

torque definition

Answer 16

muscle force causing rotary movement of a body around an axis

Question 17

Contraction definition

Answer 17

tension developed in a muscle as a result of a stimulus

Question 18

muscle contractions used to…

Answer 18

control or prevent joint movement: isometric or isotonic.

Question 19

Isometric Contraction

Answer 19

same length.
static contractions. stabilizes joints.

tension in muscle = force applied to muscle

Question 20

Isotonic Contraction

Answer 20

same tone. muscle contraction with change in muscle length. initiates or controls movement.

concentric - shortening contraction
eccentric - lengthening contraction

Question 21

Concentric Contraction. definition?

when is it used?

Answer 21

isotonic.
“coming to center”
used to initiate movement against gravity or resistance.

Question 22

Eccentric Contraction. definition? when is it used?

Answer 22

isotonic.
“away from center”
used to decelerate body segment movement.

Question 23

Line of Pull

Answer 23

direction of movement produced by the contracting muscle — origin to insertion —

Question 24

line of pull is a function of?

Answer 24

muscle’s attachment, plane of joint motion, muscle’s distance from the joint’s axis of rotation

Question 25

Angle of Pull

Answer 25

angle between the line of pull of the muscle and the bone on which it inserts - changes w every degree of joint motion

Question 26

When is the force 100% rotational?

Answer 26

when angle of pull is 90 degrees

Question 27

rotational and stabilizing forces are equal when?

Answer 27

the angle of pull is 45 degrees.

Question 28

Reverse-Action of Concentric Muscle Contractions

Answer 28

muscle w origin and insertion - (usually, one bone's attachments is more stabilized than the other so the less stabilized bone moves to the more stabilized bone.) USUALLY: biceps curl (open chain) - biceps brachii origin on scapula and insertion on radius REVERSED: a chin up - closed chain - radius is relatively stable and scapula moves

Question 29

ROM depends on?

Answer 29

muscle length of fibers. long fibers = large ROM

Question 30

Power depends on?

Answer 30

of muscle fibers. the more, the more power.

Question 31

Properties of muscle force production and movement:

Answer 31

- irritability or excitability - contractility - extensibility - elasticity

Question 32

definition: ability of a muscle to return to its original length following stretching

Answer 32

elasticity

Question 33

definition: ability of a muscle to be passively stretched beyond its normal resting length

Answer 33

extensibility

Question 34

definition: property of a muscle being sensitive or responsive to chemical electrical or mechanical stimuli

Answer 34

irritability/excitability

Question 35

definition: ability of muscle to contract and develop tension (internal force) against resistance when stimulated

Answer 35

contractility

Question 36

Agonist

Answer 36

muscle that assume major responsibility for producing a specific movement

Question 37

Antagonist

Answer 37

oppose or reverse movement by prime mover (agonist) also, helps regulate action of prime mover by partially contracting.

Question 38

Synergist

Answer 38

helper - assists same joint motion as agonist

Question 39

Stabilizer (fixator)

Answer 39

synergist. control motion of prime mover. immobilize origin or prime mover - usually isometric or eccentric pull.

Question 40

Lever definition? What does it allow you to do?

Answer 40

rigid bar that moves on a fixed point. BONES. a lever allows a muscle to move a heavier load or to move a load farther or faster than it otherwise could.

Question 41

Fulcrum

Answer 41

a fixed point of leverage. JOINTS

Question 42

Effort

Answer 42

force applied to move a resistance. TENSION (TORQUE)

Question 43

Load

Answer 43

resistance to be moved. BONE, TISSUE MASS, OBJECTS TO BE MOVED

Question 44

Function of Lever

Answer 44

convert force into torque. contracting muscle to force of rotating a bone. internal and external forces involved

Question 45

Forces involved in musculoskeletal levers produced by:

Answer 45

muscle, gravity, external physical contacts

Question 46

Mechanical Advantage

Answer 46

Power lever. load close to fulcrum effort applied far from fulcrum > small effort applied over a relatively long distance can be used to move large load over small distance

Question 47

Mechanical Disadvantage

Answer 47

Speed Lever. load far from fulcrum. effort applied near fulcrum. force exerted must be greater than load moved. load moves rapidly through larger ROM

Question 48

a ____ difference in the site of a muscle's insertion can translate into a ____ difference in the amt of force that must be generated to move a given load.

Answer 48

small difference in site of muscle's insertion = large difference in amt of force you need to move load

Question 49

First Class Lever

Answer 49

fulcrum between effort and load. think seesaw. atlanto-occipital joint: weight of face (load).... posterior cervical muscles contract (effort)

Question 50

Second Class Lever

Answer 50

load between fulcrum and effort. think wheel-barrel (fulcrum at wheel) mechanical advantage. ex. plantar flexion of foot. toe bones are fulcrum. load is the weight of your body. effort in gastrocnemius. load in between fulcrum and effort.

Question 51

Which lever class is rare in the body?

Answer 51

Second Class Lever

Question 52

Most levers in the body are which class?

Answer 52

third class levers

Question 53

Third Class Lever

Answer 53

effort applied at point between load and fulcrum. think bicep curl. load is the weight in hand. fulcrum is at elbow joint. biceps is between as effort. mechanical disadvantage

Question 54

differences in positioning of the effort, load, and fulcrum modify muscle activity w respect to:

Answer 54

speed of contraction ROM weight of load

Question 55

mechanical advantage or disadvantage? ROM lost.

Answer 55

mech adv

Question 56

mechanical advantage or disadvantage? Effort farther than load from the fulcrum.

Answer 56

mech adv