Upper Motor Neurons

Question 1

what are the two main subdivisions of upper motor neurons?

Answer 1

pyramidal
extrapyramidal

Question 2

what does the corticospinal tract of the pyramidal system control?

Answer 2

complex and fine movements
some control facilitating limb flexion

Question 3

where does the corticonuclear tract of the pyramidal system project?

Answer 3

to the brainstem

Question 4

where does the corticonuclear tract originate?

Answer 4

motor cortex

Question 5

what does the corticonuclear tract innervate in the midbrain?

Answer 5

motor nuclei of the oculomotor (III) and trochlear nerves (IV)

Question 6

how much of the white matter of the spinal cord is corticospinal tracts in primates and carnivores?

Answer 6

20-30% in primates
10% in carnivores

Question 7

what nuclei are considered part of the descending extrapyramidal system?

Answer 7

red nucleus (midbrain)
tectum (midbrain)
vestibular nuclei (pons and medulla)
reticular formation (pons and medulla)

Question 8

what is the primary regulator of voluntary locomotor activity in many animals?

Answer 8

rubrospinal system

Question 9

where does the rubrospinal tract originate from?

Answer 9

red nucleus in the midbrain

Question 10

where does the medial tectospinal tract originate?

Answer 10

tectum: rostral and caudal colliculi

Question 11

where does the medial tectospinal tract run through?

Answer 11

only through cervical spinal cord

Question 12

what is the primary function of the medial tectospinal tract?

Answer 12

orient head and neck in response to visual and auditory stimuli

Question 13

________________________________ is a bundle of bilateral fibers that connect nuclei involved with coordinating eye movement

Answer 13

medial longitudinal fasciculus (MLF)

Question 14

where does the medial longitudinal fasciculus receive input from?

Answer 14

vestibular nuclei
cranial nerves III, IV, VI

Question 15

what is the reticular formation?

Answer 15

indistinct group of cell bodies that are clustered in the core of the brainstem

Question 16

what does the pontine reticular formation facilitate?

Answer 16

standing

Question 17

what does the medullary reticular formation do?

Answer 17

suppresses standing

Question 18

what is activity in the lateral vestibulospinal tract influenced by?

Answer 18

input from vestibular nuclei from the cerebellum

Question 19

what is the lateral vestibulospinal tract important for?

Answer 19

maintaining posture
balance

Question 20

what is the medial vestibulospinal tract important for?

Answer 20

visual orienting and righting reflexes

Question 21

signs associated with damage to the cerebellum and basal nuclei are __________ impairments

Answer 21

motor

Question 22

are there direct projections from the cerebellum to the lower motor neurons?

Answer 22

no

Question 23

what does the cerebellum integrate information concerning?

Answer 23

limb and trunk position
muscle stretch
voluntary movements in process or planned

Question 24

what is the basal nuclei?

Answer 24

set of nuclei in forebrain and midbrain important for initiating and modulating movement

Question 25

what are the forebrain nuclei of the basal nuclei?

Answer 25

caudate and putamen (striatum)
nucleus accumbens
globus pallidus

Question 26

where are the main upper motor neuron nuclei found in most quadrupeds?

Answer 26

brainstem

Question 27

what do upper motor neurons do by regulating lower motor neurons in the spinal cord?

Answer 27

initiate and maintain voluntary movement
muscle tone for weight support
regulation of extensor muscle tone
partial inhibition triceps/patellar reflexes

Question 28

in whom is the corticospinal tract of the pyramidal system better developed?

Answer 28

primates

Question 29

what does the corticonuclear tract of the pyramidal system do?

Answer 29

voluntary control over cranial nerves

Question 30

the corticospinal tract controls movement on the ________________ side

Answer 30

contralateral

Question 31

how are motor neurons organized?

Answer 31

somatotopically

Question 32

what does the corticonuclear tract innervate in the midbrain?

Answer 32

motor nuclei of the oculomotor (III) and trochlear nerves (IV)

Question 33

what do extrapyramidal tracts regulate?

Answer 33

instinctive and rhythmical movement and posture

Question 34

what is the primary regulator of voluntary locomotor activity in many animals?

Answer 34

rubrospinal system

Question 35

what does the medial longitudinal fasciculus do?

Answer 35

coordinates eye movement

Question 36

does the reticular formation form distinct nuclear groups?

Answer 36

no

Question 37

where does the medial vestibulospinal tract descend to?

Answer 37

mid-thoracic cord

Question 38

clinically, what is damage to the cerebellum or basal nuclei associated with?

Answer 38

motor impairments

Question 39

what does the paravermis do?

Answer 39

regulates error correction in evolving movements

Question 40

what does the vermis do?

Answer 40

regulates muscle tone for posture and locomotion

Question 41

what is the substantia nigra?

Answer 41

contains dopamine containing cell bodies that project to striatum and play a critical role in movement
midbrain structure

Question 42

what do the lateral hemispheres of the cerebellum do?

Answer 42

project to lateral nucleus, regulate fine/skilled movement

Question 42

where does the corticospinal tract decussate?

Answer 42

level of caudal medulla