L06 Motor Pathways

Question 1

is the lower motor neuron body in the CNS or PNS?

Answer 1

CNS

Question 2

is the axon of the LMN in the CNS or PNS?

Answer 2

PNS

Question 3

name 4 major inputs from the CNS that a LMN receives input from?

Answer 3

vestibular nuclei
reticular formation
cerebral cortex (major)
red nucleus

Question 4

which side do LMNs innervate?

Answer 4

ipsilateral

Question 5

where are the LMNs in the spinal cord?

Answer 5

ventral horns

Question 6

where are the LMNs in the brainstem?

Answer 6

discrete nuclei that form the bodies of the cranial nerves

Question 7

a patient presents with hyporeflexia. where is the lesion?

Answer 7

LMN

Question 8

a patient presents with hyperreflexia. where is the lesion?

Answer 8

UMN

Question 9

biceps tendon spinal segment innervation?

Answer 9

C6

Question 10

triceps tendon spinal segment innervation?

Answer 10

C7

Question 11

patellar tendon spinal segment innervation?

Answer 11

L4

Question 12

achilles tendon spinal segment innervation?

Answer 12

S1

Question 13

name symptoms of LMN lesions

Answer 13

ipsilateral weakness
hyporeflexia
flaccid paralysis
atrophy (lack of tropins from nerves)
fasciculations (early onset)

Question 14

role of the vestibulospinal tract?

Answer 14

balance/equilibrium

Question 15

role of the reticulospinal tract?

Answer 15

gait

Question 16

role of the rubrospinal tract?

Answer 16

upper limb flexors

Question 17

role of the corticospinal tract?

Answer 17

voluntary control of skeletal muscle

Question 18

UMNs are modulated by which parts of the brain?

Answer 18

basal nuclei and cerebellum, via thalamus.

Question 19

function of the lateral corticospinal tract?

Answer 19

skilled asymmetric limb movement

Question 20

where do axons of the UMNs in the corticospinal tract synapse?

Answer 20

in the lower cervical and lumbosacral enlargements. innervate distal limb musculature for fine motor skills.

Question 21

name the path of an UMN from cortex to spinal cord

Answer 21

cortex
corona radiata
internal capsule
cerebral peduncles
pyramids
decussation of the pyramids
lateral corticospinal tract in lateral column

Question 22

name symptoms of UMN lesions

Answer 22

contralateral hemiplegia if in brain, ipsilateral if in spinal cord.
hyperreflexia
atrophy (disuse)
no fasciculations
positive babinski's sign

Question 23

lesion in CN IV nucleus affects which side?

Answer 23

contralateral

Question 24

lesion in CN IV nerve affects which side?

Answer 24

ipsilateral

Question 25

lesion in cranial nerve nuclei affects which side?

Answer 25

ipsilateral (except IV)

Question 26

babinski's sign tests for what?

Answer 26

UMN lesion

Question 27

the corticobulbar tract includes motor for which cranial nerves?

Answer 27

V, VII, IX, X, XI, XII

Question 28

which cranial nerves in the corticobulbar tract are controlled bilaterally?

Answer 28

V, IX, X

Question 29

effect of unilateral LMN lesion in the masticator nucleus (V3)?

Answer 29

ipsilateral defect | weakness in muscles of mastication

Question 30

effect of unilateral UMN lesion in the masticator nucleus (V3)?

Answer 30

little to none. (bilateral control)

Question 31

effect of unilateral LMN lesion in the nucleus ambiguus (IX, X)?

Answer 31

paresis of vocal cords, soft palate, larynx, pharynx

Question 32

effect of unilateral UMN lesion in the nucleus ambiguus (IX, X)?

Answer 32

little to none. (bilateral control)

Question 33

effect of unilateral LMN lesion in the hypoglossal nucleus (XII)?

Answer 33

paralysis of ipsilateral tongue (points in direction of lesion)

Question 34

effect of unilateral UMN lesion in the hypoglossal nucleus (XII)?

Answer 34

paralysis of contralateral tongue (points away from side of lesion)

Question 35

effect of unilateral LMN lesion in the accessory nucleus (XI)?

Answer 35

ipsilateral weakness (shoulder shrug and head turn away)

Question 36

effect of unilateral UMN lesion in the accessory nucleus (XI)?

Answer 36

contralateral shoulder weakness. | ipsilateral SCM weakness.

Question 37

effect of unilateral LMN lesion in the facial nucleus (VII)?

Answer 37

ipsilateral facial weakness

Question 38

effect of unilateral UMN lesion of the facial nucleus (VII)?

Answer 38

eyebrows unaffected. (rostral nucleus controls frontalis and is bilaterally innervated) contralateral caudal paralysis. (caudal nucleus is contralaterally innervated)