B7-004 Pain 1 Flashcards
three main somatic modalities
discriminative touch
pain and temperature
unconscious proprioception
cutaneous receptors [3]
mechanoreceptors
thermoreceptors
nociceptors
proprioceptive receptors [2]
muscle spindles
golgi tendon organs
discriminative touch receptor that functions in hair displacement
hair follicle ending
discriminative touch receptor that functions in stretch/pressure on the skin
perceive movement across the skin
ruffini endings
discriminative touch receptor that perceive pressure changes in the lips, tongue, and genitalia
krause corpuscle
discriminative touch receptor that perceives vibration and deep pressure in the dermis
pacinian corpuscle
discriminative touch receptor that perceives light (low frequency) vibration in the dermis
meissner corpuscle
discriminative touch receptor that perceive pressure of the skin in the epidermis
merkel cells
slowly adapting mechanoreceptors [2]
Merkels (small receptive fields)
Ruffini (thin, long receptive fields)
rapidly adapting mechanoreceptors [2]
Meissner’s corpuscles (small receptive field)
Pacinian corpuscles (very large receptive fields)
located everywhere throughout the cutaneous sheath and respond to mechanical, thermal, or noxious skin stimulation
free nerve endings
predominant stretch receptor within muscles
muscle spindles
muscle spindles have both […] and […] adapting components
rapidly (dynamic)
slowly (static)
provide feedback to the cerebellum about muscle length and velocity
muscle spindles
monitor stresses and forces (tension) at the tendon
golgi tendon organs
conduction velocity depends on […] and […] of the axon
fiber diameter
myelination
describe the 3 neuron pathway for perception
1st order neuron: dorsal root
2nd order neuron crosses: medulla
3rd order neuron: thalamus
terminates in somatosensory cortex
somatosensory system that gets input from discriminative touch and proprioception
dorsal column-medial lemniscus (DC-ML)
somatosensory system that gets input from temperature, pain, and very low acuity mechanosensation
spinothalamic (ALS)
(A delta and C fibers)
rank the nerve fibers in order of highest to lowest velocity
A: alpha, beta, gamma, delta
C
parasympathetic autonomic function is carried by nerves arising in the
brainstem or sacral portions of the spinal cord
contain both afferent and efferent neurons, bundling both motor and sensory functions
peripheral spinal nerves
large diameter afferent (sensory) neurons encode [2]
discriminative touch
proprioception
small diameter afferent (sensory) neurons encode [3]
pain
itch
thermal sensation
itch, pain, and thermal sensation are all encoded by
small diameter A-delta and C efferent fibers
encode stretch of skin
Ruffini
proportional to the intensity of stimulation of the nociceptor
nociceptive pain
when acute, serves an adaptive physiologic function
nociceptive pain
lowered threshold for stimulation of the nociceptor
[…] pain
inflammatory pain
adaptive/repair mechanism that allows for healing/repair of injury
inflammatory pain
sustained by aberrant processes or damage in PNS/CNS
neuropathic pain
disproportional to the intensity of nociceptor activation
serves no protective/adaptive function
neuropathic pain
chronic pain states that are stimulus independent
produced as a result of peripheral or central plasticity/sensitization
nociplastic pain
fibromyalgia is an example of
nociplastic pain
has both nociceptive and neuropathic components
mixed pain
CRPS
failed lower back surgery syndrome
no underlying lesion
pain disproportionate to degree of clinically discernible tissue injury
idiopathic pain
sensory/discriminative component of pain travels though […] tract
neospinothalamic
emotional component of pain travels though […] tract
paleospinothalamic
pain provoked by normally non-noxious stimuli
pain provoked by light brushing of skin
allodynia
pain disproportionate to the stimuli provided
hyperalgesia
are free nerve endings afferent or efferent?
both
describe the efferent activity of nociceptive nerve endings
impulse will spread along adjacent branches and activate the release of CGRP and substance P
triple response of Lewis
redness at injury (red line/rubor)
edema and swelling (wheal/tumor)
spreading redness around injury (flare)
all work together to produce dolar and calor
mechanisms of sensitization occurring in the periphery
primary hyperalgesia
mechanisms of sensitization occurring in the CNS
secondary hyperalgesia
(causes “memories” of pain)
arthritis is an example of
inflammatory pain
pain processing mechanisms function abnormally
nociplastic pain
nociception is sustained by chronic injury, causing […] pain
inflammatory pain
injured/diseased neurons
growth of axonal sprouts
formation of ectopic foci
causes […] pain
neuropathic pain
endogenous opioid peptides [3]
enkephalin
endorphin
dynorphin
**involved in endogenous analgesia (gate control theory) by binding to mu, delta, and kappa receptors
sites of action of opioid analgesics in the medulla [2]
periaqeuductal gray
nucleus raphe magnus
**small amounts of opioids acting here can drastically decrease pain because they recruit endogenous analgesia pathways
associated with limbs immobilized for long periods of time
complex regional pain syndrome
stimulation of the central gray matter in the medulla would produce
analgesia
(contains periaqueductal gray and raphe magnus)
describe pain
sensory experience with negative emotional component
small diameter, unmyelinated fibers are […] adapting
non
stimulation of […] neurons by mechanical stimuli can inhibit activity in convergent […] neurons
large diameter sensory neurons
small diameter nociceptive neurons
(gate control theory of pain)
which nerve fibers are most likely to become sensitized with repeated activation
free nerve endings
(are unable to adapt, unlike larger fibers)
pain to non-painful sensory input resulting from imbalance of non-painful and painful inputs
deafferentation pain
