Skeletal Muscle

Question 1

Myofibrils

Answer 1

Basic Unit

Question 2

Muscle Types

Answer 2

Fusiform

Penniform

Question 3

Fusiform

Answer 3

Fibers are parallel

Velocity

Question 4

Penniform

Answer 4

Fibers are pennate
Force
Uni-pennate
Bipennate
Multipennate

Question 5

Uni-pennate Example

Answer 5

Lumbricals

Question 6

Bipennate Example

Answer 6

Rectus femoris

Question 7

Multipennate

Answer 7

Gastroc

Deltoid

Question 8

Type I Muscle Fibers

Answer 8

Slow-oxidative
One joint muscles
Involved in arthrokinematics
First to atrophy
Prone to weakness

Question 9

Type IIa Muscle Fibers

Answer 9

Fast oxidative glycolytic

Question 10

Type IIb Muscle Fibers

Answer 10

Fast glycolytic (anaerobic)
Two joint muscles
Involved in osteokinematics
Prone to tightness
Dominate with fatigue/learning

Question 11

“Size Principle” of Recruitment

Answer 11

Smaller, more fatigue resistant units being used first followed by larger and more powerful units
Type I>IIa>IIb

Question 12

Motor Unit

Answer 12

Single motor neuron and muscle fibers it innervates

Question 13

Factors to Produce Force

Answer 13

Initial length (120% of resting)
Stimulus frequency (controlled by SNS)
Recruitment of motor units (type and number)

Question 14

Single Twitch

Answer 14

Single response

Question 15

Summation

Answer 15

Repeated stimulation leads to an increase in tissue

Question 16

Tetanus

Answer 16

Highest tension developed in response to high frequency of stimulation

Question 17

Motor Unit Action Potential

Answer 17

Electrical impulse that propagates along length of muscle fibers from motor endplate

Question 18

Electromyography (EMG)

Answer 18

Measure of neural activation of motor units

Electrodes placed parallel to muscle fibers

Question 19

Force-Velocity Curve

Answer 19

Concentric contraction - greater force at slower speed

Eccentric contraction - greater force with faster speeds

Question 20

Length-Tension Relationship

Answer 20

120% of resting length is greatest force production because of max cross-bridge interaction

Question 21

Moment Arm Distance

Answer 21

For same muscle force production, longest moment arm will have greatest torque

Question 22

Isometric

Answer 22

Same muscle length or joint position

Accommodative load

Question 23

Isotonic

Answer 23

Fixed resistance

Variable speed and torque

Question 24

Isokinetic

Answer 24

Constant speed

Accommodative load

Question 25

Isodynamic

Answer 25

Variable load/torque/speed

Question 26

Neurogenic Adaptation to Strength Training

Answer 26

Alterations in neural control (greater synchronicity, ability to recruit and discharge frequency)

Question 27

Hypertrophy Adaptation to Strength Training

Answer 27

Increase in muscle size