Descending Motor Pathways

Question 1

descending motor pathways

Answer 1

corticospinal tract- cortex to spinal cord
corticobulbar tract- cortex to brainstem
corticopontine tract- cortex to basilar pons

Question 2

corticospinal tract made up of fibers from:

Answer 2

primary motor area (precentral gyrus)
somatic sensory area (postcentral gyrus)
premotor area; lateral surface of cerebrum
supplementary motor area; medial surface of cerebrum
superior parietal lobule

Question 3

function of the primary motor area

Answer 3

• execution of contralateral voluntary movements

- control of fine digital movements

Question 4

lesion to primary motor area results in:

Answer 4

paralysis of contralateral muscles

Question 5

primary motor area projects to the ____ and ____ with some monosynaptic terminations on spinal cord motor neurons in the ____

Answer 5

brainstem; spinal cord; hand

Question 6

function of premotor area

Answer 6

• plans movements in response to external cues
• control of proximal and axial musculature
• may assemble empathetic facial movements

Question 7

premotor area projects to ____ and _____; some fibers project to all spinal cord levels

Answer 7

primary motor area; reticular formation

Question 8

lesion to premotor area results in:

Answer 8

• moderate weakness of contralateral proximal muscles

- loss of ability to associate learned hand movements to verbal or visual cues

Question 9

supplementary motor area function:

Answer 9

• plans movements while thinking (internally paced)
• assembles or learns new sequence
• assembles previously learned sequence
• “imagines” movements

Question 10

supplementary motor area projects to ____ and _____

Answer 10

premotor; primary motor areas

Question 11

____ and ____ project to primary motor area to direct motor patterns in response to sensory input; also project to areas of ____ and _____ to modulate sensory signals

Answer 11

somatic sensory area (postcentral gyrus); superior parietal lobule; brainstem; spinal cord

Question 12

CST has collateral projections to:

Answer 12

basal ganglia, thalamus, reticular formation, various sensory nuclei (dorsal column nuclei), posterior and intermediate horns of the spinal cord

Question 13

____ and ____ are perforating arteries off the middle cerebral a. that supply the basal ganglia

Answer 13

lateral striate aa. ; anterior choroidal a.

Question 14

corticospinal fibers descend in the ____ third of the cerebral peduncle

Answer 14

middle

Question 15

rubrospinal tract function

Answer 15

control of shoulder and proximal arm musculature

Question 16

reticulospinal tract function

Answer 16

control of axial musculature- walking

Question 17

vestibulospinal tract function

Answer 17

control of axial musculature- balance

Question 18

tectospinal tract function

Answer 18

believed to be important in head turning reflexes in response to visual stimuli ; unclear function in humans

Question 19

origin of vestibulospinal tract

Answer 19

vestibular nuclei in the pons

Question 20

vestibulospinal tract receives input from:

Answer 20

vestibular system and cerebellum (balance)

Question 21

the lateral vestibulospinal tract projects via lateral funiculus to ____ and facilitates _____

Answer 21

ipsilateral spinal cord; antigravity muscles

Question 22

medial vestibulospinal tract projects via anterior funiculus to ____ spinal cord levels bilaterally and controls ____ movements in response to gravity

Answer 22

cervical; head

Question 23

function of vestibulospinal tract:

Answer 23

• mediates postural adjustments and head movements
• antigravity reflexes
• righting reflex in cats

Question 24

lower motor neuron lesion results in:

Answer 24

• atonia
• areflexia
• flaccid paralysis
• fasciculations
• atrophy

Question 25

UMN lesions result in:

Answer 25

• spastic paralysis (paresis)
• hypertonia (increased resting tension)
• pathologic reflexes (i.e. Babinski sign, negative plantar reflex)
• milk disuse atrophy

Question 26

in the corticobulbar tract, CNs ______ receive bilateral input

Answer 26

V, VII, nucleus ambiguus (part of X), XI, and XII

Question 27

corticobulbar pathway originates in ____ portion of motor cortex and other nearby areas

Answer 27

face/mouth