Motor Control 2 - Corticobulbar Tract

Question 1

what parts of cortex contribute to UMN

Answer 1

PSC
PMS
Pre MA
somatic motor association area

Question 2

course of the corticobulbar tract

Answer 2

cortex gives out UMN
corona radiata
genu of internal capsule
brainstem
synapses with cranial nuclei
LMN to muscle

Question 3

what is a supranuclear fibre

Answer 3

UMN

Question 4

when passing through the internal capsule what is the difference between the corticobulbar and corticospinal tracts

Answer 4

bulbar in genu
spinal in post limb

Question 5

oculomotor path

Answer 5

UMN synapses bilaterally
LMN are ipsilateral

Question 6

trochlear path

Answer 6

UMN synapses bilaterally
LMN are contralateral

Question 7

trigeminal path

Answer 7

UMN synapses bilaterally
LMN are ipsilateral

Question 8

abducens path

Answer 8

UMN synapses bilaterally
LMN are ipsilateral

Question 9

facial upper nucleus path

Answer 9

UMN synapses bilaterally
LMN are ipsilateral

Question 10

facial lower nucleus path

Answer 10

UMN synapses unilaterally and contralaterally
LMN are ipsilateral

Question 11

nucleus ambiguus path

Answer 11

UMN synapses bilaterally
LMN are ipsilateral

Question 12

which CN are involved in the nucleus ambiguus

Answer 12

glossopharyngeal
vagus
cranial accessory

Question 13

hypoglossal path

Answer 13

UMN synapses unilaterally and contralaterally
LMN are ipsilateral

Question 14

spinal accessory path

Answer 14

UMN synapses bilaterally
LMN are ipsilateral to SCM and contralateral to trapezius

Question 15

which CN are exceptions to the golden rule of the corticobulbar tract

Answer 15

trochlear
facial
hypoglossal

Question 16

pseudobulbar palsy

Answer 16

this is a mild weakening of affected muscles when there is a UMN lesion in the corticobulbar tract everywhere except the lower facial and hypoglossal as these do not have bilateral synapsing of the UMN so don’t have contralateral backup - these suffer paralysis / overaction of contralateral muscles

Question 17

UMN lesion in lower facial nucleus

Answer 17

this should supply the contralateral lower quadrant of face so get paralysis here

Question 18

LMN lesion in lower facial nucleus

Answer 18

all facial muscles paralysed on ipsilateral side

Question 19

UMN lesion in hypoglossal

Answer 19

the muscle on each side of the tongue push against each other to keep the tongue central - so when the UMN is injured the tongue deviates to contralateral side when stuck out as the UMN synapses unilaterally and contralaterally

Question 20

LMN in hypoglossal

Answer 20

tongue deviates to the ipsilateral side as the LMN is ipsilateral to the nucleus and controls the ipsi muscle in the tongue