Skeletal Muscle Flashcards Preview

PTRS 711 Exam 1 > Skeletal Muscle > Flashcards

Flashcards in Skeletal Muscle Deck (27):
1

Myofibrils

Basic Unit

2

Muscle Types

Fusiform
Penniform

3

Fusiform

Fibers are parallel
Velocity

4

Penniform

Fibers are pennate
Force
Uni-pennate
Bipennate
Multipennate

5

Uni-pennate Example

Lumbricals

6

Bipennate Example

Rectus femoris

7

Multipennate

Gastroc
Deltoid

8

Type I Muscle Fibers

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

9

Type IIa Muscle Fibers

Fast oxidative glycolytic

10

Type IIb Muscle Fibers

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

11

"Size Principle" of Recruitment

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

12

Motor Unit

Single motor neuron and muscle fibers it innervates

13

Factors to Produce Force

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

14

Single Twitch

Single response

15

Summation

Repeated stimulation leads to an increase in tissue

16

Tetanus

Highest tension developed in response to high frequency of stimulation

17

Motor Unit Action Potential

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

18

Electromyography (EMG)

Measure of neural activation of motor units
Electrodes placed parallel to muscle fibers

19

Force-Velocity Curve

Concentric contraction - greater force at slower speed
Eccentric contraction - greater force with faster speeds

20

Length-Tension Relationship

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

21

Moment Arm Distance

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

22

Isometric

Same muscle length or joint position
Accommodative load

23

Isotonic

Fixed resistance
Variable speed and torque

24

Isokinetic

Constant speed
Accommodative load

25

Isodynamic

Variable load/torque/speed

26

Neurogenic Adaptation to Strength Training

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

27

Hypertrophy Adaptation to Strength Training

Increase in muscle size