Descending motor pathways

Question 1

how many motor neurones?

Answer 1

2

Question 2

upper motor neuron definition

Answer 2

from cortex to cranial nerve nucleus in brain stem or to ventral grey horn of spinal cord

Question 3

lower motor neuron definition

Answer 3

from ventral grey horn or ventral roots

Question 4

what happens if lower motor neuron is damaged?

Answer 4

muscle wasting
muscle weakness
hypotonia
absent tendon reflexes
fasciculation/fibrillation

Question 5

corticospinal nerve routes

Answer 5

cortex to spine - spinal nerves

Question 6

corticobulbar nerve routes

Answer 6

cortex to brainstem - cranial nerves

Question 7

upper motor neurons path to the brain stem

Answer 7

cerebral cortex -> precentral gyrus -> internal capsule -> brainstem/spinal cord

Question 8

interruptions of the motor neuron path leads to…

Answer 8

parkinson’s

Question 9

corticospinal does what type of movement

Answer 9

finer motor movements

Question 10

descending fibres for the body pass through

Answer 10

the posterior limb

Question 11

descending fibres for the face pass through

Answer 11

the genu

Question 12

posterior part of the posterior limb innervates what

Answer 12

the leg

Question 13

path of motor through brain stem

Answer 13

cerebral peduncles through the pons and then through the pyramids

Question 14

where does decussation for motor occur

Answer 14

the medulla

Question 15

left hand pre central gyrus controls

Answer 15

right hand side of body

Question 16

85% run

Answer 16

contralaterally

Question 17

15% run via

Answer 17

ipsilateral lateral corticospinal tract

Question 18

path of the 15%

Answer 18

cross and decussate at appropriate spinal cord level via ventral white commisure

Question 19

where do these upper motor neurons synapse?

Answer 19

ventral grey horn

Question 20

corticobulbar pathway features

Answer 20

influences lower motor neurons in cranial nerve motor nuclei

fibres originate laterally within pre central gyrus

invervation of lower motors neurons is largely bilateral with one exception

Question 21

cranial nerves with motor fibres

Answer 21

oculomotor (III)
trochlear (IV)
abducens (VI)

Question 22

cranial nerve nuclei are served

Answer 22

bilaterally

Question 23

all are served bilaterally except

Answer 23

facial and hypoglossal

Question 24

hypoglossal is served via

Answer 24

the contralateral hemisphere

Question 25

above lateral sulcus what is mapped

Answer 25

the upper face

Question 26

below lateral sulcus what is mapped

Answer 26

lower face

Question 27

upper face lower motor neurons run ipsilateral or contralateral from the facial nerve nucleus?

Answer 27

ipsilateral

Question 28

damage at lower motor neuron at parotid gland

Answer 28

ipsilateral side damaged

Question 29

upper face is served

Answer 29

bilaterally

Question 30

lower face fibres are serving

Answer 30

contralateral side

Question 31

right corticobulbar damage (UMN) would cause what damage

Answer 31

lower left face

Question 32

left facial nerve damage would cause

Answer 32

right side of face damage