Pain Pathways

Question 1

compare the 3 kinds of Nociceptors

Answer 1

A is fastest, B is middle, C is slowest and the only one unmyelinated

Question 2

_____ has a small diameter, slow conduction velocity, free nerve endings, and is myelinated

Answer 2

Adelta nociceptors

Question 3

____ is smaller than AΔ, slower conduction, free nerve endings unmyelinated

Answer 3

C nociceptor

Question 4

what type of pain comes from AΔ nociceptors?

Answer 4

sharp, first pain, short-lasting

Question 5

what type of pain comes from C nociceptors?

Answer 5

Dull, second pain, long-lasting ache

Question 6

what are the 3 pathways for non-head pain?

Answer 6

1. Δ pathway → Lateral Spinothalamic Pathway (LST)/ Neospinothalamic Tract/ Anterolateral tract
2. C pathway/ Paleospinothalamic Pathway (PST
3. Dorsal column pathway for visceral pain

Question 7

what are the steps in the Lateral Spinothalamic Pathway (LST)?

Answer 7

-First neuron cell body in the Dorsal root ganglion →
- it Synapses into Dorsal horn neurons (Laminae 1 &5) in spinal cord
-3rd neuron = VPL → Information taken to postcentral gyrus through internal capsule

Question 8

what are the steps in the C pathway/PST?

Answer 8

1. First neuron cell body in Dorsal root ganglion
2. Feeds into spinal cord (Laminae 1 & 2)
3. Terminate in intralaminar thalamic nuclei → 3rd neuron projects to insula and cingulate cortex

Question 9

how many neurons are in the 3 pain pathways for non-head?

Answer 9

3 for LST and PST, 4 for dorsal column pathway for visceral pain

Question 10

is there decussation in LST? PST?

Answer 10

• LST has immediate decussation of ALL fibers.
• PST has majority of fibers cross over, but about 10% stay on same side

Question 11

what are the 2 pain pathways for the head?

Answer 11

1. AΔ pathway: Ventral Trigeminothalamic Tract (VTTT)
2. C pathway for head

Question 12

what are the steps in the VTTT?

Answer 12

1. 1st neuron: Trigeminal ganglion
2. Synapses to cell body of Spinal nucleus in brainstem (2nd neuron)
3. synapses onto nuclei in Thalamus (VPM) (3rd neuron), then taken to higher levels of cortex
   (internal capsule and post-central gyrus)

Question 13

how many nuclei does the trigeminal nuclei have?

Answer 13

3: main, spinal, mesencephalic

Question 14

what are the steps of the head C pathway

Answer 14

1. Start at trigeminal ganglion
2. Spinal nucleus
3. Some fibers cross over, some stay on same size (collaterals spread out signal)
4. Synapse on intralaminar thalamic nuclei
   (this projects to insula and cingulate cortices)

Question 15

the ______ pathway is responsible for non-head mechanosensation

Answer 15

dorsal column-medial lemniscus

Question 16

the ______ pathway is responsible for head mechanosensation

Answer 16

dorsal trigeminothalamic

Question 17

the ______ pathway is responsible for non-head sharp pain and temperature

Answer 17

lateral spinothalamic (LST)/ AΔ pathway

Question 18

the ______ pathway is responsible for non-head dull pain

Answer 18

Paleospinothalamic (PST)/C pathway

Question 19

the ______ pathway is responsible for sharp pain/temperature in the head

Answer 19

ventral trigeminothalamic (VTTT)/ AΔ pathway for head

Question 20

the ______ pathway is responsible for dull pain in the head

Answer 20

C fiber pathway for head