Anatomy and Physiology of Pain

Question 1

What is pain

Answer 1

Subjective- varies low/high pain threshold

Symptom of injury/disease

Unpleasant

Physical/psychological experience

Complex

Protective mechanism against further damage

Question 2

Define pain

Answer 2

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage

***Pain is multi dimensional experience

Sensory = intensity location and quality
Affective = emotions associated with pain
Cognitive = thoughts associated with pain

Contribution of each= varies

Question 3

Physiologically pain threshold

Answer 3

Below this threshold pain is not evoked it is argued that it is the same level for everyone

Question 4

Pain perception threshold

Answer 4

Minimum intensity of a noxious stimulus that is required to produce a conscious perception of pain

Varies between person

Question 5

Pain tolerance level

Answer 5

Greatest intensity of noxious stimulus an individual can bare

Varies significantly

Culture,gender,motivation,social background

Question 6

Transient pain

Answer 6

Short duration, jabbing

Question 7

Acute pain

Answer 7

Brief period

Severity is variable

Question 8

Chronic pain

Answer 8

Last longer than 3 months

Pain that persists after its protective useful time

Severity varies

Question 9

What receptors detect pain

What are the types of stimuli

Answer 9

Nociceptors ( polymodal, free nerve endings)

Rapid stimulation of these receptors will be registered as pain

X3 stimuli=

Thermal
Mechanical
Chemical

Question 10

Location of nociceptors

Answer 10

Skin

Joint capsule

Connective tissue muscle

Tendon sheaths

Bone

Most tissue

Question 11

Process of nociception

Answer 11

> detect tissue damage/ harmful stimulus

> transport of nocicpetion info along peripheral nerves then in the spinal cord

> interpreted by the brain

Question 12

Transmission of nociception and other stimuli from a peripheral stimulus

X3 types of nerve fibres

Answer 12

1) Aß fibres slow
2) AD fibres rapid
3) C fibres slow

Question 13

AD fibres

Answer 13

Fast pain pathway (20/40 m/s )

small diameter myelinated

High threshold mechano: strain, thermoreceptors: ice/fire

As the frequency of discharge increases the noxious stimulus increases

Hamstring tear

Question 14

C fibres

Answer 14

slow( 2 m/s) pain pathway

small unmyelinated numerous

Mechanical thermal and chemical receptors

Dull aching/inflammation/ swelling

As the frequency of discharge increases the noxious stimulus increases

Lower back pain

Question 15

Outline the Peripheral pathway of pain

Answer 15

Nociceptor
⬇️
Named peripheral nerve
⬇️
Lumboscaral plexus
⬇️
Anterior primary ramus
⬇️
Mixed spinal nerve 
⬇️
Dorsal root
⬇️
Dorsal horn

Question 16

Difference in ramus between back and limbs+ trunk

Answer 16

Back= dorsal ramus

Limbs+ trunk= ventral ramus

Question 17

Peripheral sensitisation after injury

Answer 17

Acute pain aid healing by protecting the injured party by making it hypersensitive to external stimuli

In normal acute inflammatory response:

> Nociceptor activation thresholds are lowered so normal stimuli e.g. touch or movement now produce pain (allodynia)

> Nociceptive input is amplified and response is increased = increase the sensitivity is temporary and protective

Question 18

Central sensitisation

Basis of chronic pain

Answer 18

6 months after injury

> Increased sensitivity in spinal-cord after repeated stimulation

> Activation threshold decreased

> Response to stimulus is amplified by increased neural activity in spinal-cord

> Spontaneous activity occurs in spinal-cord as neurons influence each other by chemical release

*no pathological basis for pain but maybe physiological changes in nervous system = explain presence of pain

Question 19

Aß fibres

Answer 19

first 40 m/S

large myelinated

Touch vibration pressure proprioception 
NOT nociception (HARMFUL STIMULUS)

Question 20

What factors close the pain gate

Answer 20

1)Competitive stimulus=Incoming signals from other peripheral sensory stimulus

Massage,exercise, proprioception (accessory movements) electro therapy

2) descending pain inhibitory pathways from brain spinal-cord

Question 21

Pain modulation by descending pathways

Answer 21

Some brainstem centres can exert a downward inhibitory effect on transmission of nociception by 1st+2nd order neurons

Decsending axons travel to dorsal horn laminae l+ll to influence pain transmission/perception

Different transmitter substances involved in this pathways = OPIATES
(encephalins + endorphins)

Question 22

How can physiotherapists apply knowledge of pain in their selection of pain management strategies

Answer 22

Different strategies depending on which dimension (sensory affective cognitive) are making the most contribution

Therapeutic intervention = address all 3 dimensions to provide a holistic effective approach

Question 23

What are the Physiotherapy techniques they provide a competitive stimulus

Answer 23

Transmission by Aß fibres

Anything that normalises movement

Manual therapy – accessory techniques massage

Exercise and movement

Mobilising

Passive movements

Electrophysical modalities – high frequency (IF and tens 100- 150 Hz) uses direct stimulation of large diameter nerve fibres. Ultra sound

Question 24

What are the Physiotherapy techniques that use descending inhibition

Answer 24

Electro physical modalities e.g. low frequency IF,tens (1–15HZ)

Ice- noxious stimulus

Transverse friction massage- noxious stimulus