Lecture 4: Spinothalamic Pathway Flashcards

1
Q

What types of fibers are associated with pain and temperature?

A

Delta-cooling, 1st pain crude touch, has thin myelin C- warming, 2nd pain, no myelin

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2
Q

Where do pain and temperature fibers first enter the spinal cord/

A

Lissauer’s tract in dorsal horn next to dorsal column

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3
Q

Where do pain and temperature fibers go after they enter Lissauer’s tract?

A

Up and down 2 spinal segments before crossing midline to ventral horn

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4
Q

How does the conduction velocity of delta fibers compare to C fibers?

A

Delta fibers transmit faster because they are lightly myelinated while C fibers have no myelin

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5
Q

Where do pain and temperature nerve fibers synapse?

A

Same level +/- 2 spinal levels in contralateral ALS

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6
Q

What will happen if you cut ALS?

A

Contralateral loss of pain and temperature 2 spinal levels below lesion

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7
Q

How are 2nd order axons arranged in the ALS?

A

Sacral is lateral, cervical is medial; neurons get pushed laterally as new ones come in; delta fibers are more dorsal than C fibers

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8
Q

Where do some visceral pain fibers run?

A

Fasciculus Gracillis

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9
Q

Why do animals lick a wound?

A

Rubbing a wound activates Ab fibers which activate inhibitory interneurons which turn off pain fibers

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10
Q

Why do people scratch an itch?

A

Pruriceptive C fibers stimulate inhibitory interneurons for the itch signal but not to threshold. Scratching activates C pain fibers which then puts interneuron over threshold

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11
Q

Hyperalgesia

A

Increased sensitivity to pain

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12
Q

Allodynia

A

Pain due to stimulus that usually doesn’t cause pain

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13
Q

Mechanisms of hyperalgesia and allydynia

A
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14
Q

Where do 2nd order delta fibers synapse?

A

Ventral posterior lateral nucleus, 3rd order goes to somatosensory cortex

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15
Q

Paleospinothalamic Pathway

A

C fibers bring info to thalamus, mostly contralateral but also bilateral, which then goes to emotional areas of brain

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16
Q

How does the brain modulate pain?

A

Areas of brain project back down to spinal cord and inhibit or amplify pain fibers