Physiology of Pain

Question 1

The capability of the brain itself to suppress input of
pain signals to the nervous system by activating a pain
control system, called an

Answer 1

analgesia system

Question 2

Three main parts of analgesia system :

Answer 2

1 The Periaqueductal gray and Periventricular areas
2 Raphe Magnus nucleus
3 Pain inhibitory complex

Question 3

a thin midline nucleus
located in the lower Pons called……

Answer 3

Raphe Magnus nucleus

Question 4

Which part of analgesia system
releases Enkephalins ?

Answer 4

1- The (Periaqueductal gray) and (Periventricular areas )of mesencephalon and upper Pons
2- Pain inhibitory complex , located in the dorsal horns of the spinal cord.

Question 5

Which part of analgesia system releases serotonin ?

Answer 5

Raphe Magnus nucleus

Question 6

Neurotransmitters of Analgesic system are :
1………
2………

Answer 6

1-serotonin
2-Enkephalins

Question 7

Where can we find the pain inhibitory complex ?

Answer 7

A pain inhibitory complex located( in the dorsal
horns of the spinal cord).

At this point, the analgesia signals can block the pain before it is relayed to the brain.

Question 8

There are 2 causes of pain :
1…….
2……

Answer 8

1-Tissue ischemia
2-Muscle spasm

Question 9

What are the steps of Muscle spasm ?
And What are its types?

Answer 9

1 –Directly stimulates pain receptors

2–Indirectly :
compress vessels➡️decrease
blood flow➡️Ischemia➡️pain.

Question 10

What are the steps of Tissue ischemia ?

Answer 10

decrease oxygen ➡️
increase metabolism➡️ increase lactic acid
accumulation➡️ stimulates nerve endings
➡️pain.

Question 11

Description of Visceral Pain :

Answer 11

Description: Not localized, constant and dull,
less affected with movement

Question 12

Two Examples of Neuropathic Pain :

Answer 12

Examples: Diabetic neuropathy , cancer spread
to nerve plexus

Question 13

Description of Neuropathic Pain:

Answer 13

Burning, stabbing, pins and
needles.

Question 14

Pain receptors are :

Answer 14

free nerve endings

Question 15

Pain receptors are free nerve endings
Sites:

Answer 15

-superficial layer of skin.
-Internal tissues: (periosteum, arterial wall, joint surface &
cranial vault

Question 16

Types of stimuli excites pain receptors

Answer 16

Fast pain stimuli: Mechanical & thermal
Slow pain stimuli: All three types.

Question 17

Give me some examples of enzymes that stimulate the pain nerve
endings ?

Answer 17

bradykinin ,K ion and proteolytic
enzymes

Question 18

Hyperalgesia is : …………….

………..and……… enhance the sensitivity of pain
endings but do not directly excite them.

Answer 18

1- Increase in sensitivity of pain receptors.

2- Prostaglandins

3- substance P

Question 19

Pain Pathways :
1- ……….
2-………..

Answer 19

1-Neospinothalamic tract
2-Paleospinothalamic tract

Question 20

The fast type Aδ pain fibers terminate mainly in
lamina ………..

Answer 20

terminate mainly in lamina, I (lamina marginalis) of the dorsal horns

Question 21

What are the steps of Neospinothalamic Tract for Fast Pain?

Answer 21

1 The fast type Aδ pain fibers terminate mainly in lamina, I (lamina marginalis) of the dorsal horns, they excite second-order neurons.

2 • These second-order neurons give rise to long fibers that cross immediately to the opposite side of the cord through the anterior commissure and then turn upward.

3 few fibers of the neospinothalamic terminate in the reticular areas of the brain
stem.

4• Most pass all the way to the thalamus without interruption, terminating in the ventrobasal complex.

5• From these thalamic areas, 3rd order neurons signals are transmitted somatosensory cortex

Question 22

What are the steps of Paleospinothalamic Pathway for Slow-
Chronic Pain ?

Answer 22

• peripheral fibers terminate in the spinal cord
almost entirely in laminae II and III of the dorsal
horns

• Most of the signals then pass through one or more
additional short fiber neurons within the dorsal
horns before entering mainly lamina V.

• Here, the last neurons in the series give rise to
long axons that mostly join the fibbers from the
fast pain pathway, passing first through the
anterior commissure to the opposite side of the
cord and then upward to the brain in the
anterolateral pathway.

Question 23

What are the fibers of the Paleospinothalamic Pathway for Slow-
Chronic Pain?

Answer 23

• slow-chronic type C pain fibers,
• some signals from type Aδ fibers

Question 24

Why the Neospinothalamic Tract is localized?

Answer 24

It is because fast pain stimulate tactile receptors
that excite the dorsal column (medial lemniscal system)

Question 25

What is the neurotransmitter substance secreted
in the spinal cord at the type Ad pain nerve fiber
endings.

Answer 25

Glutamate

Question 26

…………llis the neurotransmitter most involved in transmitting fast pain
into the central nervous system, and ………is concerned with slow- chronic pain.

Answer 26

1- glutamate
2- substance P

Question 27

Where we can find The Periaqueductal gray and Periventricular areas ?

Answer 27

mesencephalon and upper Pons

Question 28

Each specific region of the body surface supplied by a
particular spinal nerve is called a ………..

Answer 28

Dermatome

Question 29

person feels pain in a part of the body that is fairly
remote from the tissue causing the pain. This is called
……..

Answer 29

Referred pain

Question 30

CAUSES of Visceral pain are :

Answer 30

Ischemia
Chemical stimuli
Spasm of hollow viscus

Question 31

Pain occurs over one side of the face in sensory
distribution area of 5 and 9 nerves

Answer 31

Tic Douloureux

Question 32

INTRACRANIAL HEAD ACHES :
1………
2………
3………
4………

Answer 32

1 Head ache of Meningitis
2 Head ache caused by Low CSF
3 Migraine Head ache
4 Alcoholic Head ache

Question 33

EXTRACRANIAL HEAD ACHES ;
1…….
2……
3…….

Answer 33

1 Head ache resulting from Muscle spasm
2 Head ache caused by irritation of Nasal and Accessory Nasal structures.
3 Head ache caused by Eye disorders

Question 34

Herpes virus infects…………Severe pain in……….. segment

Answer 34

1- Dorsal root ganglion
2-dermatomal