Chapter 10/Upper Motor Neuron

Question 1

What are the descending motor systems?

Answer 1

motor cortex

brainstem centers

Question 2

What are the descending pathways?

Answer 2

medial upper motor neuron (UMN) tract
Lateral UMN tracts
Nonspecific UMN tracts

Question 3

Medial UMN tract:

Answer 3

postural and gross movements

Question 4

Lateral UMN tract:

Answer 4

fractionated movements and distal limb movements

Question 5

What do neural centers include?

Answer 5

vestibular nuclei
reticular formation
superior colliculus

Question 6

What is the reticular formation?

Answer 6

a network of neurons in the core of the brainstem

Question 7

What are the tracts of the medial upper motor neuron (UMN) tracts?

Answer 7

medial vestibulospinal
lateral vestibulospinal
reticulospinal
medial corticospinal

Question 8

Where is the medial vestibulospinal tract from?

Answer 8

brainstem

Question 9

Where is the lateral vestibulospinal tract from?

Answer 9

brainstem

Question 10

Where is the reticulospinal tract from?

Answer 10

brainstem

Question 11

Where is the medial corticospinal tract from?

Answer 11

cerebral cortex

Question 12

What does the medial vertibulospinal tract to?

Answer 12

concerning information about head movement and position from the vestibular systems and controls neck and upper back muscles

Question 13

What does the lateral vestibulospinal tract do?

Answer 13

• Responds to gravity information from the vestibular apparatus
• facilitate LMN to extensors and inhibit LMN to flexor muscles (maintaining balance on moving vehicle)

Question 14

What does the reticulospinal tract do?

Answer 14

• Facilitates bilateral LMN innervating postural and gross movement of muscles throughout the body
• engaged in anticipatory postural adjustments (getting ready for running while awaiting go signal)

Question 15

What does the medial corticospinal tract do?

Answer 15

Has a direct connection from cerebral cortex to the spinal cord
- UMNs from this tract synapse with LMNs that control neck, shoulder and trunk muscles

Question 16

Where does the medial corticospinal tract facilitate motor neurons to?

Answer 16

neck, shoulder and trunk muscles

Question 17

Where does the reticulospinal tract facilitate motor neurons to?

Answer 17

bilateral postural muscles and gross limb movement muscles of entire body

Question 18

Where does the lateral vestibulospinal tract facilitate motor neurons to?

Answer 18

postural muscles

Question 19

Where does the medial vestibulospinal tract facilitate motor neurons to?

Answer 19

neck

Question 20

What do motor cortices do?

Answer 20

plans and directs execution of voluntary or volitional somatic movement (pyramidal motor system)

Question 21

Why are motor cortices pyramidal?

Answer 21

due to the fact that the pathway from the cortex to the spinal cord runs through medullary pyramids, also called “corticospinal tract”

Question 22

What does the motor cortex include?

Answer 22

1. primary motor cortex

2. supplementary motor area

Question 23

Where is the primary motor cortex?

Answer 23

pre-central gyrus

Question 24

What does the primary motor cortex do?

Answer 24

• governing execution of voluntary movements

Question 25

Where is the supplementary motor area (SMA) and lateral premotor cortex?

Answer 25

- part of three long frontal gyri | - superior, middle and inferior frontal gyri

Question 26

What does the supplementary motor area (SMA) and lateral premotor cortex do?

Answer 26

organize movement sequences and planning movements

Question 27

What is fractionation?

Answer 27

ability to activate individual muscles independently of other muscles - essential for ADLs

Question 28

Fractionation is part of what tract?

Answer 28

lateral upper motor neuron tract

Question 29

What happens without fractionation?

Answer 29

the fingers and thumb would act as a single unit, as they do when picking up a water bottle

Question 30

What is the most important pathway for controlling voluntary movements?

Answer 30

lateral corticospinal tract (CST)

Question 31

Where does the CST arise?

Answer 31

from motor cortex

Question 32

Where do the axons project in the CST?

Answer 32

axons project downward to pass first through the internal capsule, cerebral peduncles, anterior pons, medullary pyramids and lateral spinal cord to synapse with LMNs that control fine movements

Question 33

What percentage of CST cross midline?

Answer 33

88

Question 34

What percentage of CST travel ipsilaterally?

Answer 34

10

Question 35

What percentage of CST travel in the medial CST?

Answer 35

2

Question 36

The lateal corticospinal tract projects?

Answer 36

mainly contralateral

Question 37

The lateral corticospinal tract facilitates what?

Answer 37

fractionate movements of the distal limbs

Question 38

The retrospinal tract projects?

Answer 38

contralateral upper limb

Question 39

The retrospinal tracct facilitates what?

Answer 39

extend wrist and fingers

Question 40

Where does the lateral corticospinal tract arise?

Answer 40

fibers arise in the primary motor, premotor and SMA

Question 41

The the primary motor cortex, what is there an equivalent to?

Answer 41

somatotopy to cortical sensory representation

Question 42

What does the corticobrainstem tract facilitate?

Answer 42

lower motor neurons innervating the facial, vocalizing, eating, and large superficial neck muscles

Question 43

Where does the corticobrainstem arise?

Answer 43

fibers arise in the cerebral cortex, then project to the CN nuclei in the brainstem

Question 44

What are the two descending tracts associated with non-specific UMN?

Answer 44

1. ceruleospinal tract | 2. raphespinal tract

Question 45

When are both tracts of the non specific UMN tracts active?

Answer 45

during excessively limbic activities, hence being called part of the emotional motor system

Question 46

Where is the origin of the cereulospinal tract?

Answer 46

locus coeruleus in the brainstem

Question 47

What is the function of the cereulospinal tract?

Answer 47

enhances activity of interneurons and motor neurons throughout the spinal cord

Question 48

What is the origin of the raphespinal tract?

Answer 48

raphe nucleus in the brainstem

Question 49

What is the function of the raphespinal tract?

Answer 49

enhances activity of interneurons and motor neurons throughout the spinal cord