motor pathways W3

Question 1

what structures does the motor system incorporate

Answer 1

cerebral hemispheres
basal ganglia
cerebellum
thalamus
brain stem
spinal cord
peripheral nerve
NMJ/skeletal muscle

Question 2

where are cell bodies of lower motor neurons located

Answer 2

lamina 9 of Rexeds laminae in the ventral horn of spinal cord

Question 3

A-alpha fibre function

Answer 3

motor to skeletal muscle

Question 4

A-beta fibre function

Answer 4

sensory - touch, pressure, vibration

Question 5

A-gamma fibre function

Answer 5

muscle spindles (stetch detection)

Question 6

A-delta fibres function

Answer 6

sensory - pain (localised), temperature, touch

Question 7

B fibres function?

Answer 7

pre-ganglionic autonomic

Question 8

C fibres function

Answer 8

sensory - pain (diffuse), temperature, post-ganglionic autonomic

Question 9

neuromuscular junctions size number and variation

Answer 9

size - 50um across
number - one per muscle fibre
variation - all cholinergic (acetylcholine, excitatory)

Question 10

what can regulate the firing pattern of lower motor neurons?

Answer 10

upper motor neurons

Question 11

are upper motor neurons always excitatory?

Answer 11

no!!!!!!

Question 12

structures upper motor neurons are influenced by or reside in?

Answer 12

cerebral cortex (motor and sensory)
basal ganglia
thalamus
red nucleus
reticular formation
vestibular system
visual system
cerebellum
inferior olivary complex

Question 13

what motor function is the corticospinal pathway

Answer 13

control of voluntary and precise movement

Question 14

where are upper motor neuron cell bodies found

Answer 14

primary motor cortex
pre-motor cortex
supplementary motor cortex
cingulate motor cortex
somatic sensory cortex

Question 15

what is the corticospinal pathway from the cortex to brainstem?

Answer 15

cortical grey matter
corona radiata (axons)
internal capsule (axons)

Question 16

parts of internal capsule and function?

Answer 16

anterior limb = ascending
genu
posterior limb = descending

Question 17

external features of brain stem - anterior view - midbrain?

Answer 17

mammillary body
crus cerebri

Question 18

external features of brain stem - anterior view - pons?

Answer 18

middle cerebellar peduncle

Question 19

external features of brain stem - anterior view - medulla?

Answer 19

olive lateral to pyramid
decussation of pyramids at caudal end

Question 20

external features of brain stem - posterior view - midbrain?

Answer 20

thalamus
superior colliculus
inferior colliculus

Question 21

external features of brain stem - posterior view - pons?

Answer 21

superior cerebellar peduncle
middle cerebellar peduncle
floor of 4th ventricle
inferior cerebellar peduncle

Question 22

external features of brain stem - posterior view - medulla?

Answer 22

cuneate tubercle
gracile tubercle
fasciculus cuneatus
fasciculus gracilis

Question 23

where does the corticospinal pass after the internal capsule

Answer 23

crus cerebri of midbrain

Question 24

where does the corticospinal pass after the crus cerebri

Answer 24

pontine corticospinal tracts

Question 25

where does the corticospinal pass after pontine corticospinal tracts

Answer 25

pyramid of medulla

Question 26

where does the corticospinal pass after pyramid of medulla

Answer 26

lateral and ventral corticospinal tracts of spinal cord

Question 27

what occurs to upper motor neurons in pyramids?

Answer 27

75-90% decussate
10-25% remain ipsilateral (and decussate at level of their LMN synapse)

Question 28

where do axons run in the lateral corticospinal tract?

Answer 28

contralateral

Question 29

where do axons run in the ventral corticospinal tract?

Answer 29

ipsilateral

Question 30

extra-pyramidal motor pathways? contra/ipsilateral?

Answer 30

rubrospinal tract - contralateral
vestibulospinal tract - ipsilateral
tectospinal tract - contralateral
reticulospinal tract - ipsilateral

Question 31

where does the rubrospinal tract come from

Answer 31

red nucleus in midbrain

Question 32

where does the vestibulospinal tract come from

Answer 32

vestibular nuclei in pons and medulla

Question 33

where does the tectospinal tract come from

Answer 33

superior colliculus in midbrain

Question 34

upper motor neuron loss causes what?

Answer 34

weak voluntary movements of affected muscles
slow wasting muscle atrophy
spasticity
positive Babinski reflex

Question 35

lower motor neuron loss causes what?

Answer 35

weak or paralysed affected muscles
profound muscle atrophy
tendon reflexes weak/absent
fibrillation potentials can be recorded from denervated muscle
fasciculation occurs

Question 36

what are the basal ganglia?

Answer 36

group of subcortical nuclei that interact with each other

Question 37

parts of the basal ganglia?

Answer 37

caudate
putamen
globus pallidus external
globus pallidus internal
subthalamic nucleus
substantial nigra