Upper Motor Neurones and Control of Movement Flashcards Preview

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Flashcards in Upper Motor Neurones and Control of Movement Deck (28)
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1
Q

no input is needed from the motor cortex to rhythmically co-ordinate walking - true or false?

A

true - neuronal circuits causing flexion / extension of the legs can control this at spinal level

2
Q

describe the 3 levels of motor control?

A

strategy - aim of the movement? how can it best be achieved?

tactics - what sequence of muscle contractions and relaxations will fulfil the strategic aim?

execution - activation of neurones which command the desired movement

3
Q

what areas of the brain are involved in producing a “strategy” for movement?

A

neocortical association area and basal ganglia

4
Q

what areas of the brain are responsible for the “tactics” or a motor movement?

A

motor cortex

cerebellum

5
Q

what parts of the CNS cause execution of the planned movement?

A

brain stem

spinal cord

6
Q

what brodmanns area make up the motor cortex in pre-central gyrus?

A

brodmann areas 4+6

7
Q

name the two lateral descending motor tracts and their shared function?

A

lateral corticospinal tract + rubrospinal tract

function:

  • voluntary control of distal musculature
  • particularly discrete, skilled movements
  • involved in fractioned movement (lots of different muscles making different movements at the same time)
8
Q

there are various ventromedial pathways which descend the brainstem - name some examples and their main function?

A

ventral corticospinal
tectospinal
reticulospinal
vestibulospinal

function - control of posture and locomotion

9
Q

the ventromedial pathways are under cerebral cortex control - true or false?

A

false

the lateral pathways are under cerebral cortex control whereas the ventromedial pathways are under brainstem control

10
Q

where in the corticospinal tract does decussation of most fibres occur?

A

medullary pyramids

most fibres cross at pyramidal decussation to form lateral corticospinal tract - remainder stay ipsilateral to form central corticospinal tract

11
Q

where do axons of the lateral corticospinal tract terminate in the ventral horn of the spinal cord, and what muscles does this associate them with?

A

terminate in dorsolateral region of ventral horn

associated with distal muscles, particularly flexors

12
Q

where are cell bodies of the rubrospinal tract located, and where does this nucleus receive input from?

A

red nucleus

receives input from the motor cortex and the cerebellum

13
Q

where do fibres from the rubrospinal tract decussate?

A

at the ventral tegmental decussation

14
Q

where do fibres from rubrospinal tract terminate?

A

descends spinal cord ventrolateral to the lateral corticospinal tract and terminates in the ventral horn

15
Q

what muscles does the rubrospinal tract control?

A

limb flexor muscles

16
Q

if there is damage to only the corticospinal tract, then the rubrospinal tract has the potential to compensate for damage - true or false?

A

true

17
Q

if both lateral tracts are damaged, explain the characteristics of patients movement?

A

less fractionated - all muscles trying to do same thing at same time, movement is larger and less accurate and also slower

little effect on normal posture

18
Q

what are the two nuclei of the vestibulospinal tract?

A

medial (goes to cervical region) and lateral (goes to lumbar region)

19
Q

what is the function of signals descending via the lateral vestibular nucleus (deiters nucleus)?

A

helps to hold upright and balance posture

causes extension in antigravity muscles esp lower limb

20
Q

what is the function of signals descending via the medial vestibular nucleus?

A

activate cervical spinal circuits (neck muscles etc)

guiding head movements

21
Q

where are cell bodies of tectospinal tract found?

A

superior colliculus

22
Q

where does the superior colliculus receive input from?

A

retina
visual cortex
sensory and auditory afferents

eg helps to guide eyes to new important visual stimulus

23
Q

where do axons of the tectospinal tract decussate?

A

decussate in the dorsal tegmental decussation and descend close to the midline

24
Q

what are the two parts of the reticulospinal tract and where do they arise from?

A

pontine (medial) and medullary (lateral)

arise from the reticular formation (diffuse mesh of neurones at the core of brainstem)

25
Q

what are the functions of the medial / pontine reticulospinal tract?

A

enhances antigravity reflexes of the spinal cord

maintain standing posture by helping contract extensor muscles in the lower limbs

26
Q

what are the functions of the lateral / medullary reticulospinal tract?

A

opposes the action of medial tract

releases antigravity muscles from reflex control

27
Q

both of the reticulospinal tracts descend bilaterally - true or false?

A

false
medial / pontine descends ipsilaterally
lateral / medullar descends bilaterally

28
Q

activity in both the medial and lateral reticulospinal tract is controlled by what?

A

descending signals from the cortex