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Neurology > White Matter / Descending Pathways > Flashcards

White Matter / Descending Pathways Flashcards

0
Q

What areas do commisural fibres transmit impulses between? What is the largest of the commisural tracts?

A
  • gyri of the opposite hemisphere

- corpus callosum

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1
Q

What areas do association fibres transmit impulses between?

A

gyri in the same hemisphere

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2
Q

Where do projection fibres transmit impulses between?

A

cerebrum and other parts of the CNS via ascending and descending pathways

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3
Q

What are the four afferent fibre types?

A

1a/1b, beta, A-delta, C-fibre

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4
Q

What are the two receptor types for 1a/1b fibres?
What is their stimulus?
What is their relative axon diameter?
Are they myelinated?
What is their relative conduction velocity?

A
  • muscle spindle (1a), golgi tendon organ (1b)
  • proprioception
  • largest
  • yes
  • fastest
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5
Q 
What is the receptor for A-delta fibres?
What is their stimulus?
What is their relative axon diameter?
Are they myelinated?
What is their relative conduction velocity?
A
  • A-delta nociceptor
  • tissue injury (mechanical, thermal)
  • small
  • yes
  • slower (fast pain)
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6
Q 
What is the receptor for C-fibres?
What is their stimulus?
What is their relative axon diameter?
Are they myelinated?
What is their relative conduction velocity?
A
  • C-PMN nociceptor (polymodal)
  • tissue injury (mechanical, thermal, alogogenic chemical)
  • smallest
  • no
  • slowest (slow pain)
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7
Q

What are the 4 events between stimulus and experience? Describe them.

A
  • transduction (stimuli converted to action potentials)
  • transmission (signals enter and ascend the CNS)
  • modulation (intensity is defined)
  • perception (feeling)
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8
Q

What information does the dorsal column relay? Give 2 examples.

A

somatosensory information entering the spinal cord.

  • proprioception
  • vibratory sensations from the body (except face, mouth, head)
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9
Q

List 3 parallel ascending (sensory) tracts.

A
  • dorsal column
  • spinocerebellar tract
  • spinothalamic tract
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10
Q

Where is somatosensory information from the face, mouth and head supplied from?

A

trigeminal nerve (CN V)

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11
Q

What information do the spinocerebellar tracts relay? (2)

A
  • subconcious muscle

- joint position sense (proprioception)

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12
Q

What information does the spinothalamic tract relay? (2)

A
  • pain

- temperature

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13
Q

What does crude touch imply?

A

that a person will not be able to localize where they were touched, only that they were touched

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14
Q

What are the two sub-divisions of the spinothalamic tract called?

A
  • neospinothalamic

- paleospinothalamic

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16
Q

The neospinothalamic tract has ___ major neurons. The 1st order neuron is attached to a _______.

A

3 / A-delta nociceptor

17
Q

What tract is associated with withdrawl reflexes and escape behaviour?

A

neospinothalamic tract

18
Q

What information does the paleospinothalamic tract carry?
Via what?
Where to?
How is it interpreted?

A
  • slow pain
  • unmyelinated C-fibres
  • contralateral side
  • dull, ache, chronic pain
19
Q

In the paleospinothalamic tract, the ______ neuron is attached to a _________.

A

unipolar / C-PMN nociceptor

20
Q

What tract mediates reflexes and integrated responses (fear, memory) related to nociceptive impulses?

A

paleospinothalamic tract

21
Q

Tracts of myelinated axons (white matter) in the CNS travel in ___ directions. What are they called, and what direction are they?

A

3

  • association (anterior-posterior)
  • commisural (lateral)
  • projection (superior-inferior)
22
Q

Where are lower motor neuron cell bodies located?

A

neuraxis

23
Q

Motor (descending) pathways are divided into two main divisions called ______ and ______.

A

direct / indirect

24
Q

Direct motor pathways travel from ______ directly to ______ via the ______ tract.

A

motor cortex / lower motor neurons / corticospinal (aka. direct motor)

25
Q

Indirect motor pathways travel from the motor cortex to the lower motor neurons via the ______, ______, and ______ tracts.

A

rubrospinal / tectospinal / vestibulospinal

26
Q

What does CN VII control?

A

facial muscle (expression)

27
Q

What is the only direct connection between the motor cortex and the spinal cord?

A

corticospinal tract (aka. direct motor tract)

28
Q

About ___% of the corticospinal tract axons _______ to the other side of the body in the distal _______.

A

90 / decussate / medulla

29
Q

What separates the medulla from the spinal cord?

A

pyramidal decussation

30
Q

What is the internal capsule?

What does is consist of?

A
  • massive layer of white matter (8-10mm thick)

- ascending and descending projection fibres

31
Q

What is the major route by which the cerebral cortex is connected to the brain stem and spinal cord?

A

internal capsule

32
Q

Where is the most common stroke location?

A

part of the internal capsule which carries the corticospinal tract

33
Q

What is the rubrospinal tract directed by?

What is it’s function?

A
  • red nucleus in the brain stem

- alternative route for voluntary motor commands

34
Q

What is the vestibulospinal tract directed by?

What is it’s function? (2)

A
  • brain stem
  • maintain correct position of head and neck
  • mainaint upright posture by stimulating extensors (antigravity)
35
Q

What is the tectospinal tract directed by?

What is it’s function?

A
  • brain stem

- coordinates head and eye movement

36
Q

What is divergence?

A

information in the CNS carried by neurons to many different neurons

37
Q

What is convergence?

A

information in the CNS from many different sources sent to the same neuron/nucleus

47
Q

What information does the neospinothalamic tract carry?
Where to?
How is the information interperated?

A
  • fast pain (as well as crude touch)
  • contralateral sensory cortex
  • sharp, acute, localized pain

Neurology (4 decks)

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