Pain

Question 1

What is the definition of pain

Answer 1

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such tissue damage

Question 2

What is acute pain

Answer 2

• normal pain
• Afferents A delta and C fibres involved
• serves as a protective function

First pain - stabbing A delta fibres
Second pain - dull, aching C fibres

Question 3

Where is pain first detected

Answer 3

In the free nerve endings in the skin, dentin ect

Question 4

What are A delta fibres associated with

Answer 4

Noxious mechanical/heat

Question 5

What are C fibres usually associated with

Answer 5

Polymodal (involving more than one sense)

Question 6

Describe the somatic nociception pathway

Answer 6

Neuron 1 - peripheral sensory receptor, synapses upon entering the spinal cord
Neuron 2 - bypasses the brainstem goes to thalamus where it synapses with neuron 3
Neuron 3 - goes to the cortex produces response

Question 7

What is important about the spinothalamic tract pathway

Answer 7

Enables one to move away from pain stimuli fast

Important for survival

Question 8

What is the spinal lemniscus

Answer 8

In the medulla the two tracts merge within the spinotectal pathway and the combined tract is known as the spinal lemniscus

Question 9

What is the corticospinal tract

Answer 9

Carries information from the motor cortex to the spinal cord

Question 10

What are the large fibrous bundles that ended the midbrain when the neuron leaves the motor cortex called

Answer 10

Cerebral peduncles

Question 11

What is the difference between the corticotubular tract and the corticospinal tract

Answer 11

The corticospinal tract synapses with the lower motor neurons innervating the muscles in the limbs and the trunk

The corticotubular tract synapses at the cranial nerves to control muscular movements of the head, neck and face

Question 12

Describe the lateral corticospinal tract

Answer 12

The lateral corticospinal tract contains over 90% of the fibres present in the corticospinal tract and runs the length of the spinal cord

Question 13

What is the primary responsibility of the lateral corticospinal tract

Answer 13

Control the voluntary movement of the contra lateral limbs

Question 14

Describe the anterior corticospinal tract

Answer 14

Small bundle of decending fibres that connect the cerebral cortex to the spinal cord

Question 15

What is the difference in the lateral and anterior corticospinal tract

Answer 15

Anterior - fibres enter the medulla on the same side of the body they entered in

Lateral - fibres enter the medulla on the opposite side of the body

Question 16

Where are free nerve endings found in the teeth

Answer 16

Free nerve endings are found in the dentine

Free nerve endings send axons via the trigeminal nerve through the anterior (ventral) trigeminothalmic pathway

Question 17

What are the receptors of pain pathways

Answer 17

Nociceptors (free nerve endings)

Question 18

What axon classes are involved in pain pathways

Answer 18

A delta and C fibres

Question 19

What CNS pathways are involved in pain

Answer 19

• spinothalamic
• anterior (ventral)
• trigeminothalmic

Question 20

What areas of the forebrain is involved in pain pathways

Answer 20

Primary sensory cortex
Subcortical areas

Question 21

What details would you have to gather about a patients pain

Answer 21

• location
• quality
• intensity
• frequency/duration
• provoking/relieving agents

Question 22

In dentistry you should locate which branch of the trigeminal nerve the pain is on

Name and describe the three branches of the trigeminal nerve

Answer 22

Opthalmic - The ophthalmic nerve branches from the trigeminal nerve in the skull and begins in the lateral wall of the cavernous sinus, a cavity between the bones in the front and middle of the skull SENSORY

Maxillary - The maxillary division of the trigeminal nerve is a sensory nerve. It leaves the skull via the foramen rotundum and enters the upper part of the pterygopalatine fossa SENSORY

Mandibular - When the mandibular nerve emerges from the foramen ovale, it is located between the tensor veli palatini muscle medially, and the lateral pterygoid muscle laterally. The otic ganglion is located on its medial surface. SENSORY AND MOTOR

Question 23

What is referred pain

Answer 23

Pain tends to differ from internal organ to superficial area on the skin

Question 24

What factors can affect pain perception

Answer 24

• genetic
• molecular
• cellular
• anatomical
• physiological
• social

Question 25

What is the SC9A gene

Answer 25

Encodes x subunit of voltage gated Na+ channel nav 1.7

Question 26

What is nav 1.7

Answer 26

Nav1.7 is a voltage-gated sodium channel and plays a critical role in the generation and conduction of action potentials

Strongly expressed in nociceptive afferents (receptor endings)

Question 27

Describe why some individuals can’t feel pain

Answer 27

If there is a SCN9A mutation there is a loss of the NAv 1.7 function

Question 28

Rubbing the area of pain applies what theory

Answer 28

The gate control theory

Question 29

Describe the gate control theory in a situation where an individual has hit their knee

Answer 29

Rubbing the knee is a touch signal which starts at the same location as the pain

This stimulates mechanoreceptors

When the 1st neuron of the mechanoreceptor is in the dorsal grey horn it will branch, this small branch will synapse with another neuron that sits in between neuron 1 and 2 of the pain pathway

This is called the inhibitory inter neuron, activation of this will essentially stop the pain signal

Question 30

What is the internal capsule

Answer 30

Allows communication between areas of the cerebral cortex and areas of the brainstem

Question 31

What are the reactions to tissue damage

Answer 31

• wheal can form
• dermatographia

Question 32

What does the CGRP cause in tissue damage

Answer 32

The dilation of blood vessels

Cause the red reaction=flare

Question 33

What causes the wheal to form in tissue damage

Answer 33

Release of bradykinin