neural control of movement

Question 1

name the 4 structures that control movement

Answer 1

lower motoneurons
upper motoneurons
cerebellum
basal ganglia

Question 2

what do LMNs do?

Answer 2

produce muscle contractions via motor units

Question 3

what is the general function of UMNs?

Answer 3

produce voluntary movements

give commands to the LMNs which are effectors

Question 4

what is the function of the cerebellum in movement?

Answer 4

coordinate muscle movement - esp complicated multi-joint movements

Question 5

what is the function of basal ganglia?

Answer 5

contain motor programs for the initiation and maintenance of movements

Question 6

what are the 4 anatomical points where lower motor neuron weakness can occur?

Answer 6

origin of the signal in the anterior horn of the spinal cord
where axons go through the ventral horn then join a nerve lower down
neuromuscular junction
muscle

Question 7

what is a clinical feature of lower motoneuron damage?

Answer 7

muscle wasting esp in bulbar muscles in the tongue and the upper and lower limb

Question 8

which neurons never innervate muscles?

Answer 8

upper motoneurons

Question 9

where are UMN cell bodies found?

Answer 9

in the cerebral cortex - mainly the precentral gyrus

Question 10

what are the 3 functionally distinct motor pathways that upper motoneurons contribute to?

Answer 10

CST
rubrospinal tract
vestibulospinal and reticulospinal tracts

Question 11

what is the function of the CST?

Answer 11

precise movements

Question 12

what is the function of the rubrospinal tract?

Answer 12

large muscle movements and facilitates flexor movements

Question 13

what is the function of the o vestibulospinal and reticulospinal tracts?

Answer 13

posture & balance, muscle tone, position of head and limbs

Question 14

what does the corticobulbospinal tract supply?

Answer 14

the musculature of the head and neck

Question 15

what does voluntary movement require?

Answer 15

knowledge of where the body is in space
where it intends to go
selection of a plan and how to get there

Question 16

what are the functions of UMNs?

Answer 16

•	Excitation of muscles 
•	Inhibition of muscles 
•	Reflex modulation (e.g. Jendrassic)
•	Efference copy (important for smooth movements)
activation of other brainstem UMNs

Question 17

what is an efference copy?

Answer 17

an internal copy of a movement signal

used to reduce cognitive load by decreasing sensory processing of incoming sensory info

Question 18

what regions of the cortex are involved in motor control?

Answer 18

ore frontal cortex
frontal eye fields
pre motor cortex and supplementary cortex
primary motor cortex

Question 19

how does the anatomical position of the cortical region relate to its role?

Answer 19

the more anatomically anterior the cortical region, the more complex/abstract the role in movement

Question 20

what are the steps needed to carry out a movement and what regions assist in this?

Answer 20

decision to move - areas 5 and 7
plans to move are stored until required - association motor cortex - area 6
activation of descending pathways - area 4

Question 21

what is the result of signal mismatch?

Answer 21

uncoordinated movements

Question 22

what are the 3 main structures of the cerebellum?

Answer 22

anterior lobe
tonsils
posterior lobe

Question 23

what are the 3 main cerebellum pathways?

Answer 23

vestibulocerebellum
spinocerebellum
cerebrocerebellum

Question 24

what is the function of vestibulocerebellum pathway?

Answer 24

balance and posture

eye movements

Question 25

what is the function of spinocerebellum pathway?

Answer 25

locomotion | voluntary movements of arms and legs

Question 26

what is the function of cerebrocerebellum pathway?

Answer 26

skilled motor tasks, e.g. speech, hand-eye co-ordination and cognitive eye movements

Question 27

what are the basal ganglia?

Answer 27

a group of neurons involved in brake theory

Question 28

describe the brake theory

Answer 28

if you stay still you must brake all movements (except the reflexes that keep you in the position) to move, you must break some of these postural reflexes and release the brakes on voluntary movement

Question 29

what are the 5 nuclei of basal ganglia?

Answer 29

caudate, putamen, globus pallidus, substantia nigra, subthalamic nuclei

Question 30

what do the 5 nuclei of basal ganglia do?

Answer 30

o Involved with initiation and maintenance of motor actions – decision making o Work with motor association cortex to determine  Strength of the response  Organise correct sequences of activity

Question 31

what causes tension in muscles?

Answer 31

partial state of contraction

Question 32

what does muscle tone depend on?

Answer 32

monosynaptic reflexes

Question 33

what is muscle tone maintained by?

Answer 33

reflexively

Question 34

what regulates muscle tone?

Answer 34

descending motor pathways

Question 35

where is most of the body weight found?

Answer 35

anterior to the vertebral column

Question 36

which muscles are important in maintaining postural stance?

Answer 36

deep back muscles

Question 37

how is muscle tone constantly finely adjusted?

Answer 37

by muscle fibres contracting in relays

Question 38

what does damage to the cerebellum cause?

Answer 38

ataxia and hypotonia

Question 39

what is ataxia?

Answer 39

group of disorders that affect coordination, balance and speech

Question 40

what is hypotonia?

Answer 40

a state of low muscle tone

Question 41

what does damage to the basal ganglia cause?

Answer 41

hyper/hypokinesia

Question 42

what is hyperkinesia?

Answer 42

exaggerated unwanted movement

Question 43

what is hypokinesia?

Answer 43

decreased bodily movement

Question 44

what does damage to the associated motor cortex cause?

Answer 44

apraxia

Question 45

what is apraxia

Answer 45

difficulty performing movements they already know

Question 46

what does damage to descending pathways cause?

Answer 46

spasticity and hypertonia

Question 47

define spasticity

Answer 47

an increase in muscle tone due to the loss of inhibition of gamma motoneurons

Question 48

define rigidity

Answer 48

increase in muscle tone due to the loss of inhibition of alpha motoneurons

Question 49

what controls the strength of stretch receptors?

Answer 49

gamma motoneurons

Question 50

what causes spasticity?

Answer 50

Increased excitation/decreased inhibition of gamma MNs increases tension of intrafusal muscle fibres which becomes hypersensitive to muscle stretch

Question 51

what are neuromuscular disorders?

Answer 51

conditions affecting muscles, nerves, motor or sensory cell body or the neuromuscular junction – the area where muscle and nerve make connection

Question 52

what is the function of association motor cortex and BG?

Answer 52

strategy – planning & selecting programmes to produce desired movements

Question 53

what is the function of primary motor cortex and CB?

Answer 53

tactics – sequences of muscle contractions over time to produce smooth accurate movements

Question 54

what is the function of brainstem and spinal cord in movement?

Answer 54

execution of voluntary movement and any necessary postural adjustment.