EX1; Central Pain Flashcards Preview

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Flashcards in EX1; Central Pain Deck (31):

These nociceptors terminate mainly in the superficial laminae (I, II), although there is an important termination in layer V too; in the medullary dorsal horn (n. caudalis)



Non-nociceptive terminals are mainly where

in the deep laminae of the medullary dorsal horn


Following a peripheral nerve injury, there is postganglionic degeneration of what

c-fiber terminals in the superficial layers of the dorsal horn


Upon c-fiber degeneration in the dorsal horn after injury, what becomes of that A-fibers

the A-fibers in the deeper layers can sprout into the superficial layers, activating 2nd order pain signaling neurons in the superficial layer


What two types of neurons are found in the medially dorsal horn

nociceptive specific neurons
wide dynamic range neurons


This neuron represents convergence of a nociceptive neuron and a low-threshold A-beta type low threshold (non-nociceptive) type cell

wide-dynamic range neuron


Wide-dynamic range neurons may also have this, in which the center area is excitatory to pain and touch (wide-dynamic) but the surround is inhibitory to pain stimuli

"center surround" receptive-field organization


Activation of the center-surround receptive field may be involved with what

referred pain


Wide-dynamic range neurons in nucleus caudalis responds to what different type of stimuli

referred pain
innocuous and noxious stimuli
light touch and pressure to facial region
painful pinch and heat
electrical stimulation of TMJ and tooth pulp


True or False
the nucleus caudalis is the only part of the trigeminal complex that processes oral pain

False; it is not the only part


One frequent observation in trigeminal pain is that it is what

referred; pathology or insult to one area results in pain experienced somewhere else


Referred pain is partially explained by what in the MDH

convergence; pain and non-pain afferents converge on "pain-signaling" neurons


These fibers carry the pain message from the secondary hyperalgesia zones to the brain

A-beta fibers


How is it that the normal light touch sensation A-beta fibers carry pain signals to the brain

normal A-beta fibers release glutamate but is ineffective at the synapse because of Mg+ block in the NMDA receptor, intense pain via a C-fiber sensitizes (removes Mg block) the postsynaptic neuron to non-painful beta input


What three things involve MDH neuron response involving c-fiber activation of a-beta

depolarization by substance P
modification of NDMA receptor (remove Mg block)
increase conductance of NMDA receptor
respons to innocuous stimuli induces pain


What are the pain thresholds for healthy vs unhealthy teeth

high pain threshold for normal teeth
much lower pain threshold for inflamed teeth
lower pain threshold in contralateral healthy teeth; due to ipsilateral innervation


The inflamed teeth are "sensitizing" central neurons with what input

from healthy contralateral side to make them more sensitive


What other region in the has been shown to also be a "pain center" besides nucleus caudalis

nucleus oralis


True or False
Not all oral and facial pain is mediated by trigeminal fiber terminating in MDH



What two aspects of pain cannot be explained by brainstem mechanisms

perceptual and emotional components in the forebrain


Pain fibers terminate in midline thalamic nuclei including the nucleus submedius which projects to the cingulate cortex which then deals with which aspect of pain



Pain fibers rom the MDH cross and ascend in trigeminothalamic tract to terminate in the ventral posterior lateral nucleus (VPL) then to the somatosensory cortex which then deals with which aspect of pain

discrimination (localization); where is the pain, how intense is it, etc.


Other aspects of pain response including some reflex action is mediated by which part of the brainstem

reticular formation


What is specific about the neural response regarding the N. submedius and CC

neural response outlasts stimulus (poor localization)
also large receptive field


N. submedium and CC also deal with this

activity associated with anxiety


What is specific about the neural response regarding the VPL and somatosensory cortex

neural response track pain stimulus; onset and offset follow the stimulus closely


What is the receptive field like involving VPL and SS complex



Forebrain pathways modulate pain perception involving these two sensations

anxiety can increase pain perception
the placebo effect suppresses pain perception


There is correlation between anxiety level and degree of activation of that what

anterior cingulate cortex


This system is implicated in the placebo effect

endogenous opioid system; the perception of pain can be diminished when a patient believes they are taking medicine


Upon blocking of the endogenous opioid system, what happened to the pain levels

the pain levels felt increased