motor units and movement

Question 1

somatic nervous system

Answer 1

A branch of the Peripheral nervous system which consists of the skeletal muscles and their neural control elements

Question 2

muscle synergist

Answer 2

muscle that assists the primary movers

Question 3

biceps brachii and brachialis work together. which muscle is the primary mover ?

Answer 3

biceps brachii

Question 4

what muscles are antagonistic to biceps brachii and brachialis (as flexors)

Answer 4

triceps brachii and anconeus ( extensors )

Question 5

Axial muscles

Answer 5

muscles that control movements of the trunk

Question 6

proximal muscles

Answer 6

muscles that are found in the shoulder, elbow, pelvis and knee and the mediate locomotion

Question 7

distal muscles

Answer 7

muscles that move the hands, feet and digits

Question 8

where do upper motor neurons arise?

Answer 8

cerebral cortex

Question 9

what neurotransmitter is used by the upper motor neurons ?

Answer 9

glutamate

Question 10

where do the lower motor neurons arise from ?

Answer 10

spinal cord

Question 11

what neurotransmitter is used by lower motor neurons

Answer 11

acetylcholine

Question 12

how do lower motor neurons exit the spinal cord ?

Answer 12

in spinal nerves

Question 13

motor unit

Answer 13

α motor neuron and all of the skeletal muscle that it innervates

Question 14

motor pool

Answer 14

single muscle innervated by a group of α motor neurons

Question 15

what influences the force of contraction from an α motor neuron ?

Answer 15

• motor unit recruitment
• frequency of action potentials generated

Question 16

what do smaller motor units (small innervation ratio) control ?

Answer 16

finer movements (i.e. extraocular muscles of the eye )

Question 17

what do larger motor units control

Answer 17

postural muscles (i.e. pectoralis and erector spinae)

Question 18

how many motor neurons does a single muscle cell respond to ?

Answer 18

one

Question 19

where do the cell bodies of lower motor neurons reside

Answer 19

ventral horn of the spinal cord

Question 20

innervation ratio

Answer 20

the number of muscle fibers innervated by a single motor neuron

Question 21

what type of movement are fast fatiguing motor units for

Answer 21

short bursts of power (powerlifting)

Question 22

describe fast fatiguing motor units

Answer 22

-very high tension
- fatigues quickly
- large motor neurons and high AP threshold
- type IIx fibers

Question 23

what type of movement are fatigue resistant motor units for

Answer 23

sustained locomotion (long distance running)

Question 24

describe fatigue resistant motor units

Answer 24

-high tension
-intermediate α motor neuron and AP threshold
- type IIa fibers

Question 25

describe slow motor units

Answer 25

-low tension -fatigue resistant - small α motor neurons and low AP threshold - type I fibers

Question 26

what is the oxidative capacity for slow muscle fibers vs fast muscle fibers

Answer 26

slow - high fast - low

Question 27

myoglobin in slow muscle fibers vs fast muscle fibers

Answer 27

slow - high fast - low

Question 28

glycolytic capacity in slow muscle fibers vs fast muscle fibers

Answer 28

slow - low fast -high

Question 29

myosin ATPase activity in slow muscle fibers vs fast muscle fibers

Answer 29

slow- slow fast - fast

Question 30

fatigue resistance in slow muscle fibers vs fast muscle fibers

Answer 30

slow - high fast - low

Question 31

what is the order of motor unit recruitment

Answer 31

1) slow motor units 2) fast fatigue-resistant 3) fast fatigable (aka size principle)

Question 32

what frequency is associated with twitch muscle contractions

Answer 32

5Hz

Question 33

what frequency is associated with unfused tetanus muscle contractions

Answer 33

20Hz

Question 34

what frequency is associated with wave summation muscle contractions

Answer 34

10Hz

Question 35

what frequency is associated with fused tetanus muscle contractions

Answer 35

40Hz

Question 36

fused tetanus

Answer 36

type of muscle contraction where there is no relaxation of the muscle fibers between stimuli

Question 37

unfused tetanus

Answer 37

type of muscle contraction where the muscle fibers do not completely relax before next stimulus

Question 38

wave summation

Answer 38

muscle fibers produce stronger contractions by being stimulated rapidly before they can fully relax, resulting in an increase force of contraction

Question 39

twitch

Answer 39

single AP from a motor neuron that produces a single contraction in the muscle fiber