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Nervous System > Anatomy and Physiology > Flashcards

Anatomy and Physiology Flashcards

1
Q

how many descending white matter tracts are there in the spinal cord?

A

6

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2
Q

what are the two main classifications of descending motor tracts in the spinal cord?

A

lateral (pyramidal) and ventromedial (extrapyramidal)

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3
Q

which motor tracts are lateral/pyramidal tracts?

A
  • lateral corticospinal tract

- rubrospinal tract

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4
Q

which motor tracts are ventromedial/extrapyramidal?

A
  • tectospinal tract
  • vestibulospinal tract
  • medullary reticulospinal tract
  • pontine reticulospinal tract
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5
Q

what is the function of the tectospinal tract?

A

it stabilises eyes during movement

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6
Q

what is the function of the vestibulospinal tract?

A

it steadies the head and neck

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7
Q

what is the function of the lateral pyramidal tracts?

A

voluntary control of fine movement

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8
Q

what is the function of the reticulospinal tracts?

A

control of axial muscles for body positioning and posture

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9
Q

what is the decussation of the pyramids?

A

the point in the medullary pyramids where the corticospinal tract fibres cross over to the opposite side

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10
Q

where does the rubrospinal tract begin?

A

in the red nucleus in the midbrain

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11
Q

what structure in the brain is the 3rd ventricle associated with?

A

diencephalon

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12
Q

what structure in the brain is the cerebral acqueduct associated with?

A

midbrain

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13
Q

what structure in the brain is the 4th ventricle associated with?

A

posteriorly - cerebellum

anteriorly - pons and medulla

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14
Q

which two motor tracts complement eachother?

A

corticospinal tract and rubrospinal tract

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15
Q

where do the pyramidal tracts originate from?

A

cerebral cortex

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16
Q

where do the extrapyramidal tracts originate from?

A

brainstem

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17
Q

what are the two simultaneous actions of corticospinal tract neurons?

A

1 - monosynaptic excitation of agonist motor neurons

2- inhibition of antagonist motor neurons (through interneurones)

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18
Q

which motor neurons are activated by lateral corticospinal tracts? what action do they carry out?

A

distal limb muscles - voluntary movement

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19
Q

what is the somatotopic distribution of lower motor neurons in the spinal cord?

A

axial and proximal muscles medially

distal muscles laterally

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20
Q

are the actions of the ventromedial motor pathways voluntary or reflexes?

A

reflexes

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21
Q

are the actions of the lateral motor pathways voluntary or reflexes?

A

voluntary

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22
Q

what area of the brain (name and Brodmann area number) is responsible for planning movements?

A

premotor cortex - Brodmann area 6

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23
Q

what do PMA and SMA stand for, and what muscles do they each innervate?

A 
PMA = premotor area - innervates proximal motor units
SMA = supplementary motor area - innervates distal motor units
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24
Q

what kind of neurons are found in the corpus striatum?

A

medium spiny neurones

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25
Q

what is the corpus striatum composed of?

A

caudate nucleus and putamen

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26
Q

what actions does firing of the caudate nucleus predict?

A

eye movements

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27
Q

what actions does the firing of the putamen predict?

A

body/limb movements

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28
Q

what are the main steps of the basal ganglia direct pathway? what kind of neurotransmitter signal does each step send?

A
  • cortex to corpus striatum - excitatory (glutamate)
  • corpus striatum to globus pallidus (internal) - inhibitory (GABA)
  • globus pallidus to thalamus (VLo) - reduced inhibition
  • thalamus (VLo) to Area 6 (SMA) - excitatory (glutamate)
29
Q

which area of the thalamus is involved in the basal ganglia pathway?

A

VLo - ventral lateral nucleus in dorsal thalamus

30
Q

what is the resting state of the thalamus?

A

inhibited by action of globus pallidus

31
Q

what is the function of the indirect basal ganglia pathway?

A

to stop antagonistic movements from being activated by the thalamus

32
Q

what is the corticopontocerebellar tract, and what is its function?

A

a large projection tract from the somatosensory cortex to the pons and cerebellum, involved in motor control

33
Q

which area of the cortex is activated as a result of the direct basal ganglia pathway?

A

supplementary motor area (SMA)

34
Q

how does cerebellar information get fed back to the SMA for motor control?

A

cerebellum –> superior cerebellar peduncles –> ventrolateral thalamus –> back to motor cortex

35
Q

which two types of neurons are involved in motor pathways?

A

upper and lower motor neurons

36
Q

how many different neurons are involved in a sensory pathway?

A

three - first, second and third order neurons

37
Q

what sensations does the spinothalamic tract carry?

A

pain and temperature

38
Q

what sensation does the dorsal column tract carry?

A

proprioception, vibration and light touch

39
Q

what are the three common characteristics of first, second and third order sensory neurons involved in ascending pathways?

A
  • first order neuron always pseudounipolar with a dorsal root ganglion
  • second order neuron always the one to cross to contralateral side
  • third order neuron always starts in contralateral medulla
40
Q

what is the crossover point of ascending fibers from the dorsal column?

A

gracile and cuneate nuclei in medulla

41
Q

what is the crossover point of ascending fibers from the spinothalamic tract?

A

spinal cord

42
Q

at which level of any ascending pathway does the third order neuron get activated?

A

at the contralateral thalamus

43
Q

what is the dorsal column tract called after crossover at the cuneate and gracile nuclei?

A

medial lemniscus

44
Q

which nerve fibres carry pain sensation?

A

A delta

C fibres

45
Q

name some characteristics of A beta fibers and what sensations they carry

A

large diameter
myelinated
mechanoception

46
Q

name some characteristics of A delta fibers and what sensations they carry

A 
medium diameter
myelinated
mechanoception
fast pain (nociception)
pressure
47
Q

name some characteristics of C fibres and what sensations they carry

A

small
unmyelinated
carry slow pain
temperature (hot)

48
Q

which lamina of Rexed receive pain input?

A

mainly 2 and 5

49
Q

which system is involved in modulating descending pain pathways?

A

PAG (periacqueductal grey) pathway

50
Q

what is the gate control theory with regards to pain sensation?

A

firing of A-beta fibres and PAG fibres may activate inhibitory interneurons, which block the firing of C fibres

51
Q

how does the PAG mechanism modulate pain?

A

through action at 5HT, NA and opioid receptors

52
Q

what is the difference between pain and nociception?

A

pain - subjective experience

nociception - physiological stimulus to tissue damage

53
Q

which type of pain (acute or chronic) is physiological?

A

acute pain

54
Q

define the three types of peripheral sensitisation to pain

A

allodynia - reduced threshold for nociception
hyperalgesia - increased neuronal firing for non-painful stimulus
spontaneous pain - independent firing of neurons with no physiological cause

55
Q

define the three types of central sensitisation

A

wind up: only affects affected synapses, increased firing when stimulus increases, firing stops when stimulus stops
classical: new synapses triggered in response to painful stimulus, firing outlasts stimulus
long-term potentiation: adaptation of affected synapses as result of repeated stimulus to that area

56
Q

list the three types of central pain sensitisation

A

wind up sensitisation
classical sensitisation
long-term potentiation

57
Q

list the three types of peripheral pain sensitisation

A

allodynia
hyperalgesia
spontaneous firing

58
Q

what is normally the cause of neuropathy?

A

nerve damage

59
Q

at which stages of the pain pathway can drugs modulate it?

A

transduction (peripheral afferents)
transmission (to thalamus)
response (descending pathway)

60
Q

which two systems are involved in modulating pain, according to the gate control theory?

A
  • A-beta fibre firing

- PAG (periacqueductal grey) and NRM (nucleus raphe magnum) firing

61
Q

which molecules are used to inhibit pain sensation in the gate control theory?

A

opioid peptides (endorphins)

62
Q

explain the mechanism of action of NSAIDS

A

they block cyclo-oxygenase, which converts arachidonic acid to prostaglandins

63
Q

explain the mechanism of action of local anesthetics

A

they block sodium channels, stopping depolarisation of afferent neurons

64
Q

explain the mechanism of action of opiates

A

desensitise nociceptors
trigger inhibitory interneurons in dorsal horn
trigger PAG/NRM descending pathway

65
Q

list some chemical triggers found in injured tissue which can activate the pain pathway

A 
low pH
temperature
bradykinin
histamine
prostaglandins
66
Q

what are the three areas of the brain that are essential for forming, accessing and storing memories?

A

forming - hippocampus
accessing - thalamus
storing - cortex

67
Q

name the four types of memory

A
  • immediate
  • short term memory
  • intermediate term memory
  • long term memory
68
Q

name the four structures involved in the Papez circuit

A
  • hippocampus
  • mammillary bodies
  • thalamus
  • cingulate cortex

Nervous System (3 decks)

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