Motor Unit

Question 1

Initial tension and length of the relaxed fibers, prior to their activation

Answer 1

Preload

Question 2

The opposing force against which a muscle pulls when its activated

Answer 2

Afterload

Question 3

Extrafusal fiber is innervated by____

Answer 3

a single alpha motor neuron

Question 4

The particular group of fibers innervated by one particular alpha motor neuron

Answer 4

Motor unit

Question 5

T/F each muscle fiber is innervated by one alpha motor neuron

Answer 5

True

Question 6

T/F each alpha motor neuron innervates one muscle fiber

Answer 6

False- alpha motor neurons innervate many muscle fibers

Question 7

Force generated by a muscle is dependent on what 2 variables

Answer 7

Strength of activation to each neuron fibers (frequency)

Number of fibers activated ( # of motor units)

Question 8

T/F all motor units are all or none

Answer 8

True- a motor unit is active or not, there is no inbetween

Question 9

Expresses how many fibers are innervated by one alpha motor neuron

Answer 9

Innervation ratio

Question 10

Muscles that require precise adjustment in force (ration)

Answer 10

Small innervation ratio

Question 11

Muscles that produce large sustained levels of force

Answer 11

large innervation ratio

Question 12

Duration and peak force measured in a single twitch

Answer 12

response characteristic

Question 13

long contraction time, less force production but fatigue resistant (muscle type)

Answer 13

slow-twitch muscle

Question 14

Short contraction time, great force production but quick to fatigue

Answer 14

fast-twitch muscle

Question 15

T/F Muscle contraction is all or none

Answer 15

False- depends on motor unit recruitment and level of activation of motor units

Question 16

T/F Slow twitch fibers are activated first then Fast twitch

Answer 16

True

Question 17

T/F All muscles are a mix of slow and fast twitch fibers

Answer 17

True

Question 18

____ neurons supply slower, weaker motor neurons

Answer 18

Smaller neurons

Question 19

____ neurons supply faster, stronger motor neurons

Answer 19

Larger neurons

Question 20

The size of the EPSP is ____ proportional to the size of the neuron

Answer 20

inversely proportional

Question 21

The external load determines how much _____ must be generated by the muscle

Answer 21

Counteracting force

Question 22

What are the three parts to voluntary movement

Answer 22

perception
cognition
action

Question 23

development of a “unified sensory representation” of the

external world and the individual within it

Answer 23

Perception

Question 24

decision to initiate a course of action that incorporates the
current perception of the individuals place (location) within the external
world

Answer 24

cognition

Question 25

development of a plan that models the intended action, followed by execution of that plan

Answer 25

action

Question 26

Execution of the motor plan involves both ______ and ______ signaling

Answer 26

feedforward and feedback signaling

Question 27

Feedback runs through the ___ to make corrections of ongoing movements

Answer 27

Cerebellum

Question 28

What reflexes help with feed back in motor planning

Answer 28

spinal level reflexes Myotatic reflexes inverse myotatic reflexes

Question 29

located with the motor regions of the cortex (e.g. primary motor cortex), and within the brainstem (e.g. vestibular nuclei, superior colliculus, reticular formation)

Answer 29

upper motor neurons

Question 30

alpha and gamma motor neurons within the ventral horns of the spine, and the motor nuclei of the cranial nerves located within the brainstem

Answer 30

lower motor neurons

Question 31

descending motor commands that direct fine and specific | movements originate from the______

Answer 31

primary motor cortex

Question 32

The motor plan is developed in these two area

Answer 32

Premotor cortex and supplementary motor cortex

Question 33

“movement planning” relayed to | the supplementary motor cortex via the thalamus

Answer 33

basal ganglia

Question 34

“computation and feedback” relayed to the primary motor and premotor areas via the thalamus

Answer 34

Cerebellum

Question 35

Rather than controlling just one particular muscle, signaling from individual corticomotoneurons is often distributed to pools of lower motor neurons to initiate____- muscular actions

Answer 35

coordinated

Question 36

Specific movements require ___ of neurons to activate

Answer 36

Specific pools