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Neuro Mini Exam > Corticobulbospinal Tracts & Basal Ganglia Motor Systems I > Flashcards

Corticobulbospinal Tracts & Basal Ganglia Motor Systems I Flashcards

1
Q

GSE

A

somatic motor system
-descending tract

voluntary control of skeletal m.

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2
Q

GVE

A

visceral motor system

-autonomic nervous system

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3
Q

motor system

A

motivation - frontal lobes
motor plan - premotor cortex
action - primary motor cortex

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4
Q

motivation

A

coming up with idea for motor plan

  • need input:
  • sensory stimuli (parietal motor area)
  • emotions/memory (limbic)
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5
Q

motor plan

A 
module or blueprint for movement
-what muscles, what order, what timing
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6
Q

premotor cortex

A

brodmans areas 6 and 8 lateral

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7
Q

supplementary cortex

A

brodmans areas 6 and 8 medial

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8
Q

action

A

UMN - from primary motor cortex and brainstem nuclei

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9
Q

UMN

A

influence LMNs
-spinal cord and cranial nerve

all UMNs converge on LMNs to produce movement

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10
Q

final common pathway

A

LMNs

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11
Q

alpha-lower motor neurons

A 
ventral horn and cranial nerve motor nuclei
synapse on skeletal m.
always excitatory
release ACh
target ipsilateral
large cells
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12
Q

gamma-lower motor neurons

A

muscle spindle

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13
Q

baseline activity

A

allows for fine adjustment
-in alpha LMNs

sets muscle tone

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14
Q

inputs to LMNs

A

local reflex arc
local pattern generators
UMN input

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15
Q

motor unit

A

all muscle fibers innervated by single LMN

  • size related to function
  • fine control vs. power
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16
Q

small motor unit

A

less fibers innervated

-fine control

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17
Q

large motor unit

A

1000 fibers/neuron - power control

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18
Q

each muscle fiber

A

only innervated by 1 LMN

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19
Q

individual muscle

A

have motor units of various sizes

-although certain sizes may predominate

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20
Q

action potential

A

all or none

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21
Q

regulation of muscle contraction strength?

A

AP frequency

recruitment of motor units

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22
Q

size principle

A

recruit small > large motor units

small first**

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23
Q

UMN

A

influence LMNs

  • directly
  • or indirectly
  • excitatory or inhibitory
  • never synapse on muscle**
  • cell bodies in cerebral cortex and brainstem nuclei
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24
Q

8 different UMN pathways

A

2 from primary cortex

6 from brainstem

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25
Q

lateral motor system

A

distal limb movement

-precise movement

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26
Q

medial motor system

A

proximal limb movement

-postural movement

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27
Q

lateral vs. medial

A

lateral - lateral funiculus

medial - anterior funiculus

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28
Q

influence on UMNs?

A

basal nuclei
association cortex
cerebellum

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29
Q

corticobulbar tract

A

cortex to brainstem

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30
Q

non-cortical UMN systems

A

reflex - postural movements
-in brainstem

-input from cortex influences these systems (gain voluntary control)

31
Q

cortical UMN systems

A

distal limb movements

-fine movement

32
Q

cortical UMN pathways

A

lateral corticospinal
-cortex to spinal cord b/l

corticobulbar tract

33
Q

corticospinal tract lateral

A

largest tract of humans
contralateral projection
fine, fractionated movement

34
Q

course of UMN on corticospinal tract

A 
internal capsule
cerebral peduncles (midbrain)
longitudinal fibers of pons (pons)
pyramids (medulla)
pyramidal decussation
lateral corticospinal tract
35
Q

brodmans area 4

A

primary motor cortex

precentral gyrus

36
Q

voluntary motor movement

A

posterior limb of internal capsule

facial expression - genu
upper limb - anterior
lower limb - posterior

37
Q

premotor cortex

A

lateral brodmans area 6 and 8

  • motor planning
  • active at START of movement
38
Q

supplementary cortex

A

medial brodmans areas 6 and 8
interconnected with contralateral side
-bimanual movements

active right before movement takes place

39
Q

corticobulbar tract

A

terminates in brainstem

influence cranial LMNs
also to UMN nuclei
-voluntary control of proximal muscles

40
Q

cranial nerve motor nuclei

A

most receive input from both right and left cortex

41
Q

corticobulbar influence on brainstem UMNs

A

vestibular nuclei
reticular nuclei
red nucleus

give rise to medial motor systems
-proximal limb

42
Q

LMN damage signs

A

hypo to areflexis
hypo to atonia
paralysis/paresis - flaccid
rapid, severe atrophy

43
Q

partial paralysis

A

NO

actually a paresis

44
Q

neurogenic atrophy

A

due to loss of LMN

45
Q

spontaneous EMG changes

A

with LMN damage

46
Q

fasciculations

A

can see visually twitching

47
Q

fibrillations

A

with EMG

48
Q

UMN damage signs

A 
normal - hyperreflexia
hypertonia
pathological reflexia (babinski)
spastic paralysis
disuse atrophy (slower)

few EMG changes

49
Q

babinski

A

is a pathological reflex

  • stroking of foot
  • UMN damage - toes flare is abnormal
  • curling normal
50
Q

hyperreflexia with UMN damage?

A
  1. loss of normal inhibitory background
  2. sprouting of local afferents - increased input from the initial primary afferent imput
  3. receptors to membrane
51
Q

denervation hypersensitivity

A

increased expression of receptors on surface of LMNs and interneurons

52
Q

partial paralysis

A

NO

paresis

53
Q

plegia

A

stroke

54
Q

hemi

A

half

55
Q

para

A

pair of limbs

56
Q

quadra

A

four limbs

57
Q

stroke lesions

A

affects many different systems

58
Q

damage to corticospinal systems

A

levels below lesion
LMN signs at lesion level
UMN signs inferior to lesion

59
Q

lesion above decussation

A

contralateral signs

60
Q

lesion below decussation

A

ipsilateral signs

61
Q

extrapyramidal system

A

non-contrical UMN system

62
Q

non-cortical UMN systems

A

proximal limb

  • reflex posture
  • also voluntary control - corticobulbar tract
63
Q

medial vestibulospinal tract

A

descending medial longitudinal fasciculus

64
Q

anterior corticospinal tract

A

technically a cortical UMN tract

-but, its bilaterally, neck muscles, posture function

65
Q

rubrospinal tract

A

lateral motor system

-begins in brainstem

66
Q

rubrospinal tract

A

cell bodies in red nucleus

  • axons decussate in midbrain
  • descend contralaterally in lateral funiculus

-to cervical cord only

  • *distal muscles of arm
  • arm/forearm flexors

very small in humans

67
Q

vestibulospinal tracts

A

medial and lateral tracts

68
Q

medial vestibulospinal tract

A

aka descend MLF
cell bodies in medial/inferior vestibular nucleus
-axons descend bilaterally through cervical and upper thoracic

**neck muscles, head posture

69
Q

lateral vestibulospinal tract

A

cell bodies in lateral vestibular nucleus
-axons descend ipsilateral

** antigravity muscles
entire cord to trunk posture

*** damage - ipsilateral deficits

70
Q

medial longitudinal fasciculus

A

ascending
cell bodies in medial.inferior vestibular nucleus

  • *ascends to innervate III, IV, VI
  • extraocular muscles of eye

**bilateral

71
Q

reticulospinal tract

A

medial and lateral

cell bodies - reticular formation

back up when corticospinal fibers are damaged (theory)

72
Q

pontine reticulospinal tract

A

medial

**ipsilateral

73
Q

medullar reticulospinal tract

A

lateral

**bilateral

74
Q

tectospinal tract

A

superior colliculus - cell bodies

  • axons decussate in midbrain
  • descend contralateral

end in cervical levels

**neck, postural muscles

**visual grasp reflex

Neuro Mini Exam (7 decks)

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