Head and Face Pain Neurophysiology

Question 1

What is Nociception?

Answer 1

The activity in a neural structure capable of leading to or contributing to a sensation of pain.

Question 2

What are the four steps for the Nociceptive pathway?

Answer 2

1. Transduction
2. Transmission
3. Modulation
4. Perception

Question 3

What is Transduction?

Answer 3

Primary Afferent Nociceptor activation from noxious stimulus

Question 4

What is Transmission?

Answer 4

The coded message traveling from the Primary Afferent Nociceptor into the dorsal horn of the spinal cord

Question 5

What is Modulation?

Answer 5

The change or attenuation of a nociceptive stimulus in the grey matter of the spinal cord

Question 6

What is perception?

Answer 6

The coded message traveling from the dorsal horn to the contralateral cortex.

Question 7

What are pain r/c’s classified as?

Answer 7

Free nerve endings that are slowly adapting with a high threshold.

Question 8

What are the types of free nerve endings?

Answer 8

1. Mechanical
2. Thermal
3. Polymodal

Question 9

What are mechanical free nerve endings?

Answer 9

Receptors that respond to sharp penetration. They are faster conducting and more localized.

Question 10

What are thermal free nerve endings?

Answer 10

Receptors that are activated by temperature extremes.

Question 11

What are polymodal free nerve endings?

Answer 11

Receptors that are activated by mechanical, chemical, and thermal stimuli.
Deep burning with poor localization.
Ex: Lactate in Muscles

Question 12

What are the Nociceptive fiber types?

Answer 12

A-delta and C fibers

Question 13

What are A-delta fibers?

Answer 13

Thinly Myelinated
Smaller Diameter
Slow Conducting (5-30m/s)
Pricking Pain
More Accurately Localized

Question 14

What are C fibers?

Answer 14

Unmyelinated
Smaller Diameter
Slow Conducting (0.25-0.35 m/s)
Burning
Poorly Localized

Question 15

What is released during the localized effects of pain stimuli?

Answer 15

There is a release of Substance P, Calcitonin, CGRP, Neurokinase A, and other inflammatory mediators.

Question 16

What do the release of inflammatory markers during pain stimulation result in?

Answer 16

Resulting in vasodilation, transport of plasma, and contraction of smooth muscles.

Question 17

What do the localized effects of pain stimuli play a role in?

Answer 17

Peripheral sensitization of tissue along with other sympathetic responses

Question 18

Describe the Pain Pathway from Pain to WDRN with Stress.

Answer 18

Stress simulates the adrenals to produce cortisol and NE/E, sensitizing the C-fiber
Pain activates C-fibers from the nociceptor act on NMDA r/c’s to stimulate the WDRN.

Question 19

Describe the Pain Pathway from WDRN to PMRF.

Answer 19

Activation of the WDRN stimulates the cortex, which sends collaterals to the PMRF.

Question 20

What are the 4 functions of the PMRF?

Answer 20

1. Decrease the IML bilaterally.
2. Decrease the sensitivity to pain.
3. Increase global muscle tone
4. Decrease tone of the anterior muscles above T6 and the posterior muscles below T6.

Question 21

Describe the pain pathway from the LDA to the Cortex and PMRF.

Answer 21

LDA stimulate the AMPA r/c on WDRN nuclei directly and indirectly through interneurons. They also stimulate the cerebellum, which sends stimulatory neurons to both the Cortex and the PMRF.