Neurophysiology 3: Motor System (Lecture 77)

Question 1

What does the two motor system consist of?

Answer 1

Upper Motor Neuron (UMN)
Lower Motor Neuron (LMN)

Question 2

What does the upper motor neuron control?

Answer 2

Controls LMN, initiates voluntary motor

Question 3

Where is the Upper Motor Neuron located in?

Answer 3

Within the CNS- “Central”
-Cerebral Cortex
-Brainstem

Question 4

What does the Lower Motor Neuron innervate, and control?

Answer 4

Innervates skeletal muscles
Spinal reflexes

Question 5

Where are lower motor neurons located?

Answer 5

Cell body in ventral grey horn of the spinal cord or brainstem—“peripheral”

Compromise peripheral motor neurons

Question 6

What does conscious motor activity require?

Answer 6

A conductor

Question 7

What can LMN work independently to produce?

Answer 7

“Automatic” movement

“Stereotyped” movement

Question 8

What is the “conductor” of the motor system?

Answer 8

Cerebrum

Question 9

What is the function of the frontal cortex of the cerebrum?

Answer 9

Plans, strategizes, and provides impulse control

Question 10

Where does the frontal cortex of the cerebrum send its plan?

Answer 10

Basal nuclei

Question 11

What does the primary motor area initiate?

Answer 11

Voluntary motor movements

Question 12

What does the primary motor area output to?

Answer 12

Brainstem UMN
Spinal Cord LMN

Question 13

What are the parts of the basal nuclei (ganglia)

Answer 13

Deep Cerebral grey matter
Striatum—caudate, putamen, accumbens
Globus pallidus

Question 14

What are not considered basal nuclei, but work in the system?

Answer 14

Substantial nigra
Subthalamic nuclei

Question 15

What part of the cerebrum is responsible for planning?

Answer 15

Cerebral Cortex

Question 16

What sends inhibiting signals to thalamus?

Answer 16

Globus pallidus

Question 17

When the thalamus is in a ________ state, meaning it is _____ sending impulses back to the cerebral cortex.

Answer 17

Static state
NOT sending impulses

Question 18

What is the striatum a part of?

Answer 18

Basal Nuclei

Question 19

What/Where does the striatum send signals to?

Answer 19

Inhibitory signals to the Globus pallidus

Question 20

If you INHIBIT the Globus pallidus, what is the effect?

Answer 20

“Inhibit the inhibitor”
Green light to thalamus to send excitatory signals to cerebral cortex

Question 21

What are the three pathways of the Descending Motor tracts, that the cerebral motor controls ?

Answer 21

Corticonuclear
Corticopontine
Corticospinal

Question 22

Where does the Corticonuclear go?

Answer 22

Motor cortex of cerebrum -> brainstem nuclei

**runs ipsilateral

Question 23

Where does the corticopontine go?

Answer 23

Motor cortex of cerebrum -> pontine nuclei

**pontocerebellar fibers to contralateral cerebellum

Question 24

Cerebral cortex involved with ________ side of the body

Answer 24

Contralateral side of the body

Question 25

The cerebellum is involved with the _______ side of the body

Answer 25

Ipsilateral

Question 26

Where does the corticospinal go to?

Answer 26

Cerebral cortex -> decussate to contralateral corticospinal tract -“pyramidal tract”

Question 27

What pathway is responsible for DIRECT communication between cerebral cortex UMN and LMN.

Answer 27

The pyramidal tract *responsible for fine motor control

Question 28

What type of activity does the pyramidal tract create?

Answer 28

Voluntary motor activity

Question 29

What are the three upper motor neurons from the brain stem?

Answer 29

Red nucleus Pontine and Medullary Reticular nuclei Vestibular nuclei

Question 30

Pyramidal tracts have a ____ to _____ connection.

Answer 30

One to One One upper motor neuron synapses with One lower motor neuron

Question 31

Extrapyramidal tracts has _____ synapses than actually involved.

Answer 31

More

Question 32

What is the tract for the red nucleus called? What is a key tract for? What does it Facilitate?

Answer 32

Rubrospinal tract Key tract for voluntary movement in animals Facilitate UMN of flexor muscles

Question 33

What is the key tract for voluntary movements in animals?

Answer 33

Rubrospinal tract

Question 34

What does the pontine reticulospinal tract facilitate? Inhibit?

Answer 34

Facilitate: LMN of extensor muscles Inhibit: LMN of flexor muscles

Question 35

What does the Medullary reticulospinal tract inhibit? Facilitate?

Answer 35

Inhibit: LMN of extensors Facilitate: LMN of flexors

Question 36

What two extrapyramidal tracts balance each other out?

Answer 36

Pontine reticulospinal tract Medullary reticulospinal tract

Question 37

What does the vetibulospinal tract facilitate?

Answer 37

Facilitate: LMN of extensors Inhibit: flexors

Question 38

Where are the lateral corticospinal tract, medullary reticulospinal tract, and Rubrospinal tract in the lateral section of the brain?

Answer 38

Lateral funiculus

Question 39

Where are the pontine reticulospinal tract and ventral corticospinal tract in the lateral section of the brain?

Answer 39

Ventral funiculus

Question 40

Which has the largest diameter fibers?

Answer 40

Proproceptive fibers

Question 41

Which has the smallest diameter fibers?

Answer 41

The nociceptive fibers

Question 42

Are nocicpetive or proprioceptive fibers faster?

Answer 42

Proprioceptive

Question 43

Which fibers are least resistent to compressive injury? Which are most resistent?

Answer 43

Proprioceptive Nociceptive

Question 44

Which fibers recover first?

Answer 44

Nociceptive THEN motor THEN proprioception

Question 45

Where are somatic motor neuron cell bodies found?

Answer 45

Ventral horn

Question 46

Where are visceral motor neuron cell bodies found?

Answer 46

Intermediolateral substance (lateral horn)

Question 47

The somatic lower neuron ______ the lower motor neuron. It is a _____ neuron pathway

Answer 47

IS One

Question 48

The autonomic motor neuron has an ________ ______.

Answer 48

Autonomic ganglion Preganglionic neuron Postganglionic neuron

Question 49

What is a motor unit?

Answer 49

Somatic motor neuron and the muscle fibers it innervates

Question 50

What do alpha motor neurons innervate?

Answer 50

Extrafusal muscle fibers

Question 51

What is the role of alpha motor neurons? (Somatic lower motor neuron)

Answer 51

Contraction of extrafusal muscle fibers

Question 52

What do gamma motor neurons innervate?

Answer 52

Contractile poles of intramural muscle fibers of the muscle spindle

Question 53

What is the role of gamma motor neurons? (Somatic lower motor neuron)

Answer 53

Contraction of poles of intramural fibers stretches the muscle spindles

Question 54

What are two types of somatic lower motor neurons?

Answer 54

Alpha motor neurons (outside the muscle spindle) Gamma motor neurons (inside muscle spindle)