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motor and neuromuscular control Flashcards

1
Q

what is meant by hierarchical organisation in motor control

A

high order areas of hierarch are involved in more complex tasks e.g coordinating muscle movement
lower level areas perform lower level tasks e.g execution of movement

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2
Q

what is meant by functional segregation in motor control

A

motor system is organised in number of different area that control diff aspects of movement

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3
Q

what are the major descending tracts

A

pyramidal tracts - corticospinal and corticobulbar
extrapyramidal -
vestibulospinal, tectospinal, reticulospinal,rubrospinal

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4
Q

what makes a tract pyramidal

A

pass through pyramids of medulla

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5
Q

what is the pathway for pyramidal tracts

A

motor cortex to spinal cord or cranial nerve nuclei in brainstem

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6
Q

what is the pathway for extrapyramidal tracts

A

brainstem nuclei to spinal cord

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7
Q

where is primary motor cortex located

A

precentral gyrus

anterior to central sulcus

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8
Q

what is role of motor cortex

A

controls fine, discrete, precise voluntary movements

provides descending signals to execute movement

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9
Q

where is premotor cortex located

A

anterior to primary motor cortex

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10
Q

what is role of premotor cortex

A

involved in planning movement

regulates externally cued movements e.g seeing picking up object

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11
Q

where is supplementary motor area located

A

anterior and medial to primary motor cortex

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12
Q

what is role of supplementary motor area

A

involved in planning complex movements, internally cued e.g speech

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13
Q

what is the pathway in corticospinal tract and what muscles are involved

A

upper motor neurones in cortex travel down to medulla where 85-90% of fibres decussate and innervate limb muscles = lateral corticospinal tract
10-15% are uncrossed fibres which innervate trunk muscles = anterior corticopinal tract

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14
Q

what is corticobulbar tract responsible for

A

providing voluntary movements of face mostly and neck muscles too

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15
Q

what is role of vestibulospinal tract

A

stabilise head during body movements
coordinate head movements with eye movement
mediate postural adjustments

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16
Q

what is the role of reticulospinal tract

A

= most primitive descending tract, from medulla and pons

responsible for changes in muscle tone associated with voluntary movement and postural stabilty

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17
Q

what is tectospinal tract responsible for

A

originates from superior colliculus of midbrain

orientation of head and neck during eye movements

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18
Q

what is rubrospinal tract responsible for

A

originates from red nucleus of midbrain
mainly taken over by corticospinal tract
innervate lmn of flexors of upper limb
* comes into play when lesions to cns

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19
Q

what are the negative (loss of function) signs caused by upper motor neurone lesion

A

loss of voluntary motor function
paresis - graded weakness of movements
paralyis (plegia) - complete loss of voluntary muscle activity

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20
Q

positve signs (unwanted) sign of umn lesion

A 
increased abnormal motor function due to loss of inhibitory descending inputs
spasticity - increased muscle tone
hyper-reflexia - exaggerated reflexes
clonus - abnormal muscle contractions
babinskis sign
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21
Q

what is apraxia

A

disorder of skilled movement
lesion of inferior parietal lobe and frontal lobe
stroke and dementia are most common causes

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22
Q

what can a lower motor neurone cause

A 
weakness
hypotonia
hyporeflexia
muscle atrophy
muscle atrophy
fasiculations - twitching
fibrillations - spontaneous twitching of individual muscle fibres
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23
Q

what is motor neurone disease

A

progessive neurodegenerative disorder of motor system
affects both umn and lmn
aka amyotrophic lateral sclerosis

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24
Q

what are the umn signs of mnd

A 
spacticity
brisk limb and jaw reflexes
babinski sign
loss of dexterity
dysarthria - difficulty swallowing
dysphagia - difficulty swallowing
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25
Q

what are some lmn signs of mnd

A 
weakness
muscle wasting
tongue fasciculations and wasting
nasal speech 
dysphagia
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26
Q

what structures make up the basal ganglia

A

caudate nucleus
lentiform nucleus (putamen and external globus pallidus)
nucleus accumbens
subthalamic nuclei
ventral pallidum,claustrum,nucleus basalis
thalamus
amygdala

27
Q

what is the function of basal ganglia

A
  • decision to move
  • elaborating associated movements e.g swinging arms when walking
  • moderating and coordinating movement
  • performing movements in order
28
Q

what is parkinsons disease

A

degeneration of dopiminergic neurones that originate in substantia nigra to striatum

29
Q

signs/symptoms of parkinsons

A 
bradykinesia - slow movement
hypomimic face - emotionless
akinesia
rigidity
tremor at rest
30
Q

what is huntingtons disease

A

degeneration of GABAnergic neurones in striatum,caudate and putamen

31
Q

what does huntingtons disease cause

A

choreic movemtns - dance
rapid jerky involuntary movements of body,hands and leg first and then rest of body
speech impairment
dysphagia
unsteady gait
later stages - cognitive decline and dementia

32
Q

what is ballism

A

usually from stroke affecting subthalamic nucleus
sudden uncontrolled flinging of extremitis
symptoms occur contralaterally

33
Q

what is cerebellum

A

located in posterior cranial fossa
separated from cerebrum above by tentorium cerebelli
coordinator and predictor of movement

34
Q

what is the vestibulocerebellum

A

part of cerebellum
regulation of gait,posture and equilibrium
coordination of head movements with eye movemt

35
Q

what can damage to vestibulocerebellum cause

A

syndrome similar to vestibular disease leading to gait ataxia and tendency to fall

36
Q

what is the spinocerebellum

A

responsible for coordination of speech
adjustment of muscle tone
coordination of limb muscles

37
Q

what can damage to spinocerebellum cause

A

degeneration and atrophy related with chronic alcoholism

affects mainly legs, causes abnormal gait and stance

38
Q

what is the cerebrocerebellum

A

coordination of skilled movements
cognitive function,attention,processing language
emotional control

39
Q

what can damage to cerebrocerebellum cause

A

damage to arms/skilled coordinated movements(tremor)and speech

40
Q

what are the main signs of cerebellar disorders

A 
ataxia - impairments in coordination
dysmetria - inappropriate force
intentional tremor 
dysdiadochokinesia - inability to perform rapidly alternating movements
scanning speech - staccato
41
Q

what are alpha motor neurones

A
  • lower motor neurons of brainstem and spinal cord
  • occupy anterior/ventral horn of grey matter of spinal cord
  • innervate the extrafusal muscle fibres of skeletal muscle
42
Q

what does activation of alpha motor neurones cause

A

muscle contraction

43
Q

what is a motor neurone pool

A

all the alpha motor neurones which go to an individual muscle

44
Q

what is a motor unit

A

a single motor neurone together with all the muscle fibres that it innervates = smallest functional unit

45
Q

on average how many muscle fibres does each motor neurone supply

A

600

46
Q

what does small innervation ratio allow

A

small fine precise control of that muscle

47
Q

what are the 3 types of muscle fibres

A

slow type - s,1
fast, fatigue resistant, - fr,2a
fast, fatiguable - ff, 2b

48
Q

describe slow motor unit muscle fibres

A

smallest diameter cell bodies
small dendritic trees
thinnest axons
slowest conduction velocity

49
Q

describe fast muscle fibres

A

large diameter cell bodies
large dendritic trees
thicker axons
faster conduction velocity

50
Q

what are motor unit types classified by

A

amount of tension generated, speed of contraction and fatiguability

51
Q

how else can cns regulate force produced

A

recruitment of number of neurones and rate coding/firing

52
Q

what is meant by the ‘size principle’

A

smaller units are recruited first generating small amounts of force and more are recruited if more force is required

53
Q

what happens when firing rate increases

A

force produced by unit increases

54
Q

what are neurotrophic factors

A

are a type of growth factor
prevent neuronal growth
promote growth of neurons after injury

55
Q

what is the reason behind plasticity of motor units/muscle fibres

A

fibre types can change properties under different conditions e.g type of nerve innervating them

56
Q

what is the most common muscle fibre type change

A

fast fatiguable to ffr

2b to 2a

57
Q

when can changes from type 1 to 2 occur

A

cases of severe deconditioning / spinal cord injury

microgravity during spaceflight can result in shift from slow to fast type muscle fibres

58
Q

what is ageing associated with

A

loss of type 1 and 2

more type 1 fibres in aged muscle

59
Q

what is a reflex function

A

automatic response to stimulus that involves nerve impulse passing inward from nerve centre then outward to effector without reaching level of consciousness

60
Q

jendrassik manoevre

A

larger reflex when patellar tendon tapped

works by reducing inhibition of brain action

61
Q

what is hyper- reflexia

A

overactive reflexes
loss of descending inhibition
associated with UMN lesions

62
Q

what is clonus

A

involuntary and rhythmic muscle contractions

loss of descending inhibition

63
Q

what is babinskis sign

A

stimulate sole of foot with blunt instrument
curling upwards is abnormal
associated with umn lesion

64
Q

what is hyporeflexia

A

below normal/ absent reflexes

associated with lmn disease

brs2 (65 decks)

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