Somatosensory And Pain

Front 1

A-alpha fibers

Back 1

Muscle spindle and stretch
Large diameter
Super Fast conduction

Front 2

A-beta fibers

Back 2

Muscle spindle and mechanoreceptors
Medium diameter
Fast conduction

Front 3

A-delta fibers

Back 3

Cool, noxious heat, mechanical sensation (nociceptors)
Medium diameter
Slower conduction

Front 4

C fibers

Back 4

Warmth, noxious cold, mechanical sense (nociceptors)
Small diameter
Very slow conduction

Front 5

Glabrous skin end organs

Back 5

Meissners corpuscles
Pacinian corpuscles
Merkel disks
Ruffini's corpuscles

Front 6

Hairy skin end organs

Back 6

Pacinian corpuscles
Merkel disks
Ruffini;s corpuscles
Hair receptors

Front 7

Meissner's corpuscles

Back 7

Only in non-hairy skin
Small, near surface
Rapidly adapting
For vibration and fine touch

Front 8

Pacinian corpuscles

Back 8

Deeper and large
Rapidly adapting
Vibration and fine touch

Front 9

Merkel disks

Back 9

Slow adapting
Coding of spacial features of a stimulus

Front 10

Rufinni's corpuscle

Back 10

Slow adapting
Activated by skin stretch

Front 11

Hair receptors

Back 11

Extremely sensitive to movement
Rapidly adapting

Front 12

Proprioceptors
(5)

Back 12

1. Free nerve endings
2. Pacinian corpuscles
3. Ruffini's corpuscles
4. Muscle spindles
5. Cutaneous receptors
A-alpha and A-beta

Front 13

Innocuous warmth sensation

Back 13

Free afferents with TRPV3/4 ion channels
Increase firing rate until warmth is noxious
C-fibers

Front 14

Innocuous cool sensation

Back 14

Free afferents with TRPM8 ion channels also activated by menthol
Increase firing rate until cold is noxious
A-delta fibers

Front 15

Nociceptors
(C-fibers)

Back 15

Second pain
Free nerve endings with TRPV1/2 ion channels
Also bind capzasin
Slow, burning, anching

Front 16

Nociceptors
(A-delta fibers)

Back 16

First pain
Noxious heat
Noxious mechanoreceptor

Front 17

Selective deactivation
(3)

Back 17

1. Anesthesia - smallest fibers first (may feel first pain but not second pain)
2. Compression - largest fibers first
3. Electrical stimulation - largest fibers first

Front 18

Acute pain vs inflammatory pain

Back 18

Acute pain is due to noxious mechanoreceptor or thermoreceptor stimulus
Inflammatory pain is from tissue damage and prostaglandin synthesis

Front 19

Analgesia

Back 19

Pain is still percieved, but no longer bothersome

Front 20

Anesthesia

Back 20

Pain is no longer percieved do to blocking of the action potentials

Front 21

Peripheral targets for analgesia/anesthesia
(4)

Back 21

1. Prostaglandin synthesis
2. Nerve block
3. Sympathetic block for maintained pain
4. Dorsal rhizotomy - removal of the dorsal root

Front 22

Loss of dorsal column

Back 22

Loss of some descrimination and regulation of movements

Front 23

Loss of anterolateral column

Back 23

Loss of pain and temperature
(transient)

Front 24

Wide dynamic neuron

Back 24

In dorsal horn
Large receptive fields with local gradients
Fires for all stimuli, most intensely with noxious stimuli
In lamina 5

Front 25

Nocioceptive specific neuron

Back 25

In dorsal horn
Small receptive field
Only reponds to noxious stimuli
Lamina 1

Front 26

Referred pain

Back 26

Pain fibers for certain organs synapse onto the same areas as sensory cutaneous dermatomes

Front 27

Excitatory spinal neurochemistry

Back 27

Primary affarents for pain release Sub P and glutamate
Long acting NT's

Front 28

Inhibitory spinal neurochemistry

Back 28

Neurons in the dorsal horn are loaded with opioid receptors
GABA, glycine, and alpha-2 receptors play inhibiting role

Front 29

Spinal targets for pain control
(2)

Back 29

Opioid receptors
Na channels

Front 30

Thalamus
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 30

Relay to the cortex and modulation of information
Lesions may produce contalateral increase in pain threshold or cause central chronic pain
Target for DBS and opioids

Front 31

Primary somatosensory cortex
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 31

Receives pain information for localization and intensity
Lesions lead to increased pain threshold or central pain
May be opioid target

Front 32

Secondary somatosensory cortex
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 32

Receives pain information for localization and intensity
Lesions lead to increased pain threshold or central pain
Opioid target

Front 33

Anterior cingulate gyrus
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 33

Produces the negative affect of pain, the expectation of pain, and the attentional aspect
Lesions lead to decrease in affective response to pain
Major opioid target

Front 34

Insular cortex
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 34

Expectation and evaluation of pain
Lesions disrupt understanding and significance of pain
Major opioid target

Front 35

Prefrontal cortex
- Role in pain
-Effects of lesions on pain
- Therapy targets

Back 35

Important in evaluation, memory affect, and pain evaluation
Lesions disrupt understanding and significance of pain
Major opioid target, also affected by placebo!

Front 36

Gate control theory

Back 36

Hurt your hand and shake/rub it
Larger fibers (A-alpha and beta) for other senses have priority over pain fibers and inhibit their expression

Front 37

Locus cereleus
Periaqueductal gray

Back 37

Serotinergic relay leads to stimulation of these areas and production of endogenous opiate peptides

Front 38

Spinomesencephalic and spinoreticular tracts

Back 38

Branches off of the anterolateral tract that go to the pontine reticular formation and other thalamic nuclei (interlaminar) to produce affect of pain

Front 39

Qualitative pain measures

Back 39

Descriptors

Front 40

Quantitative pain measures

Back 40

Assessment of magnitude
Own rating scale
Ordinal/Nominal

Front 41

Allodynia

Back 41

Pain evoked from a normally non-painful stimulus
Ie: sunburn in the shower

Front 42

Hyperalgesia

Back 42

Excessive pain from a normally painful stimulus
Ie: opening a door onto a cut toe

Front 43

Neuropathic pain

Back 43

Caused by a primary lesion or dysfunction in the nervous system
Ie: post-herpetic neuralgia, complex regional pain syndrome

Front 44

Post-herpetic neuralgia symptoms and treatment

Back 44

Resting pain
Allodynia and hyperalgesia
Sensory loss
Treat with TCA's and opioids

Front 45

Complex regional pain syndrome symptoms and treatment

Back 45

Regional or sensory changes following a noxious event
Constant burning, allodynia, hyperalgesia
Not limited to a single nerve
Treat with nerve blocks, PT, opioids, anticonvulsants

Front 46

Central sensitization to pain

Back 46

Wide dynamic range neurons get excessive glutamate and get sensitization of NMDA/AMPA
These WDR neurons respond more robustly to all signals

Front 47

Non-opioid analgesics

Back 47

NSAIDS - inhibit COX production

Front 48

Adjuvant analgesics

Back 48

Primary purpose is not for pain, but can be used in selective situations