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Anatomy and Physiology > A & P - Motor nervous system > Flashcards

A & P - Motor nervous system Flashcards

1
Q

what does the motor nervous system consist of?

A

cerebral motor centres
upper motor neurones (UMN)
lower motor neurones (LMN)

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2
Q

in which direction is afferent information sent?

A

from muscles and sensors to CNS (sensory nervous system)

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3
Q

in which direction is efferent information sent?

A

from the CNS to muscles (motor nervous system)

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4
Q

what are the functions of the cerebral motor centres?

A

involved in planning, initiation and regulation of movement

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5
Q

name the cerebral motor centres

A 
primary motor cortex (+ pre-motor)
basal ganglia
cerebellum
brainstem
spinal cord
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6
Q

where are upper motor neurones located?

A

cell body of neurone is in primary motor cortex and synapse onto LMN in spinal cord

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7
Q

where are lower motor neurones located?

A

cell body in grey matter of spinal cord synapse with muscle

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8
Q

what function does the cerebellum have in the motor nervous system?

A 
balance
posture
locomotion
makes adjustments to movement
manual dexterity
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9
Q

what function do the pre-motor areas have in the motor nervous system?

A

plan complex movement

coordinates movement

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10
Q

what function does the primary motor cortex have in the motor nervous system?

A

initiates voluntary muscle movement
skilled movements
somatotopic

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11
Q

what function does the basal ganglia have in the motor nervous system?

A

associated movements
facilitates wanted movements
suppresses unwanted movements

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12
Q

what is the function of the UMNs?

A

transmit commands from motor cortex to LMNs

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13
Q

UMNs form descending tracts, where?

A

in white matter of spinal cord

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14
Q

what do UMNs do in the spinal cord?

A

decussate (cross over) to the opposite side

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15
Q

which part of the motor nervous system can be found in the grey matter of the spinal cord?

A

cell bodies of MN
interneurons
neuroglia

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16
Q

which part of the motor nervous system can be found in the white matter of the spinal cord?

A

myelinated and unmyelinated axons organised into ascending and descending tracts

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17
Q

under what control are the motor neurones in the descending tracts of the spinal cord?

A

somatic

autonomic

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18
Q

which tracts form the cortico-bulbar tract?

A

lateral cortio-spinal tract

anterior cortio-spinal tract

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19
Q

which tract is involved in he cortio-spinal pathway and what is its function?

A

cortico-bulbar tract

conscious control of skeletal muscle

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20
Q

where are the cell bodies of the UMNs in the cortio-spinal pathway located and what is their destination?

A

cell bodies : primary motor cortex

destination : spinal cord LMNs

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21
Q

where in the spinal cord are the cell bodies of LMNs found?

A

grey matter (ventral horn)

22
Q

describe the journey of an impulse from along the LMN to the muscle fibre

A
  1. myelinated axon exits spinal cord via ventral root
  2. travels to muscle via peripheral nerve
  3. On entry to muscle axon splits and synapses with muscle fibre at NMJ
23
Q

what does a motor unit consist of?

A

single LMN and all the muscle fibres it innervates

24
Q

what do small motor units allow for?

A

fine control movement (eg. eye)

25
Q

what do large motor units allow for?

A

strength

26
Q

how many muscle units innervate 1 muscle fibre?

A

1

27
Q

up to how many LMNs can innervate a single muscle?

A

100

28
Q

what clinical assessments might be used to judge motor neurological functioning?

A

observation - posture, symmetry
coordination, balance, proprioception
muscle strength - resistance to applied force
muscle tone - resistance when joints moved passively
deep and superficial reflexes

29
Q

what is clonus?

A

rhythmic, involuntary muscle contractions when stretching

30
Q

how is muscle strength regulated and which is the most important?

A
  1. number of active motor units - recruitment
  2. frequency of action potential - reduced frequency (brief force, twitching)/ increased frequency (sustained increased force (tetani)
    RECRUITMENT is most important
31
Q

what is the ‘simple’ tendon jerk reflex?

A

single, fast monosynpatic reflex

32
Q

can the ‘simple’ tendon jerk reflex persist after spinal cord section?

A

yes

33
Q

what modulates the ‘simple’ tendon jerk reflex?

A

higher cerebral centres

34
Q

what is reciprocal inhibition?

A

during the stretch reflex the antagonist muscle is often inhibited.

35
Q

how can the withdrawal reflex be tested?

A

plantar reflex

Babinski sign

36
Q

what is the withdrawal reflex?

A

complex poly-synaptic reflex with longer latency

37
Q

when is the withdrawal reflex seen?

A

in response to pain stimulus

38
Q

what is the withdrawal reflex sometimes accompanied by?

A

cross extension of extensor muscles in contralateral leg (avoids fall)

39
Q

what is the withdrawal reflex modulated by?

A

stimulus intensity

40
Q

what can nervous motor system lesions cause?

A

muscle weakness - loss of power/strength

paralysis - complete or partial

41
Q

what does the following terms mean? hemiplegia, quadriplegia, paraplegia?

A

hemiplegia - one sided paralysis
quadriplegia - all four limb paralysed
paraplegia - lower body paralysis

42
Q

what is the difference between myopathy and neuropathy?

A

myopathy - affects muscle fibres

neuropathy - LMN axon and/or cell body

43
Q

where can LMN lesions be found?

A

muscle fibres

LMN axon and/or cell body

44
Q

what are the symptoms of LMN lesions?

A

muscle weakness/loss of function
muscle wasting
fasciculation
reduced muscle tone and reflexes

45
Q

what is fasciculation?

A

involuntary muscle movements

46
Q

give an example of a muscle fibre disease (myopathy)

A

muscular dystrophy

47
Q

given an example of motor neurone disease

A

amyotrophic lateral sclerosis

48
Q

what is Bell’s Palsy?

A

inflammation of the peripheral nerves

49
Q

what is Sciatica?

A

compression of peripheral nerves

50
Q

where can UMN lesion be found?

A

axons in descending tract of spinal cord

cell bodies in motor area of brain

51
Q

what are the symptoms of UMN lesions?

A 
increased muscle tone
muscle paralysis/weakness
no muscle wasting
increased stretch reflexes
no fasciculation
contralateral signs

Anatomy and Physiology (15 decks)

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