Lecture 3- Ss system- ALS Flashcards by Caitlyn Griffin

what are the types of free nerve endings

c fiber= none myelinated
A delta= poorly myelinated

slow conduction

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where are free nerve endings

peripheral process in the epidermis

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what is the clinical importance of free nerve endings

protection - paper cut

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what are the function of free nerve endings

crude (non- discriminative touch)
itich
temp
pain
taste/smell

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true/false
Free nerve endings have the same density and receptive field as other cutaneous receptors

True

however, they are not as diffused throughout the body as other receptors

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true/false
Free nerve endings do not encode intensity as increase in frequency for AP.

False

duration, frequency, and amplitude are the same for all cutaneous receptors

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what are the functions of free nerve endings when they function as thermoreceptors

17-45 deg C cold to hot
below 17 or above 45= pain
chemical sensations from CN V (flavor of food)

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what is hyperalgesia

over-reaction of pain to the noxious stimuli

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where is hyperalgesia

only in peripheral process

increased rest membrane potential- less stimuli to cause AP

activated silent receptors

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where are silent nociceptors

jt capsule and visceral organs

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what is the axonal reflex for cutaneous receptors

axon terminals have afferent and efferent functions

one axon terminal reaches AP d/t pain and sends info to CNS
while other axon terminals reach out to blood vessels and mast cells for damage control

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what nerve fibers for free nerve endings react to m stretch or contraction after exertion

a delta

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what nerve fibers for free nerve endings react to m ischemia or after injury

c fibers

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what nerve fibers for free nerve endings react to jt pain

both a delta and c fibers respond to the inflammation

peripheral sensitization- silent nociceptors

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what types of viscera pain does c fibers respond to

mechanical- overdistension or traction
ischemia
endogenous compounds- diffuse and always have referral patterns, kidney stones

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what is a dermatome

segmental distribution of a sp n
- overlapping in both peripheral and central processes of sensory neurons
-radiculopathy

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what fibers are tested with pin prick dermatome testing

a delta

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what is the clinical importance of TENS

shallow
AB neurons
conduct faster for pain management

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what is the clinical importance of NMES

deeper (different electricity)
Aa
large axon- easier conduction, increase stimuli for activation

what is the oder neurons for ALS

1- DRG
2- innocuous input: lateral dorsal horn (laminae I-V) or noxious input (all laminae in I/IIo/V)
3- VPL or reticular formation

what laminae and neurotransmitters do a delta fibers use in ALS

laminae I and V
glutamate- ionotropic

what laminae and neurotransmitters do c fibers use in ALS

laminae I, II and V
substance P- metabotropic

what laminae do a delta and c fibers share

laminae III and IV

where is noxious and innocuous input within laminae somatotopy

innocuous is more lat
noxious is more med

what fibers are more common for the functions of sharp pain, crude, and temp

a delta contralateral projection

what fibers are more common for the functions of diffuse pain

c fibers

what tract is in the lateral fasciculus and also known as the lateral spinothalamic

neospinothalamic pathway

what path in the ALS uses c fiber mainly in the somatic

paleospinothalamic in anterior fasciculus also known as ant spinothalamic

what path in the ALS uses c fiber mainly in the visceral

archispinothalamic mutiple synapse in dorsal column

where do the c fibers travel to in the spinoreticular tract

reticular formation- intralaminar and centromedian nucleus then to insula, frontal lobe, limbic lobe

what does the lissauers tract transiton to when ascending to the medulla

spinal trigeminal tract

what does laminae II-IV transition to when ascending to the medulla

spinal trigeminal nuclei

what is the first order neuron of spinal trigeminal pathway

CN V: trigeminal ganglion CN VII: geniiculate ganglion CN IX/X: sup ganglion

how is the lissauers tract formed in the sp cord

central process to spinal trigeminal tract to lissauers tract in sp cord (cervical)

what is the second order neuron of spinal trigeminal tract

spinal trigeminal nuclei

where does the spinal trigeminal nuclei start and end

caudal pons to C2 level

how can CN VII/IX/X be involved with the sp trigeminal distribution in sp trigeminal tract

those CN follow the nuclei and also why the outer ear can be affected due to projecting to adjunct nucleus inf and post

what is the third order neurons in the sp trigeminal tract

contra VPM then progress to lateral postcentral gyrus to maintain somatotopy

what fibers are used in the sp trigiminal tract

free nerve endings- a delta

what is the ant trigeminothalamic tract

sp trigeminal tract

what is PICA syndrome

wallenburg syndrome alternating hemiplegia

how do we have alternating hemiplegia in PICA syndrome

ALS: decussate along sp so since this happens in the medulla, you have contra body pain/temp/crude impaired sp trigeminal: decussate in thalamus so this is ipsi facial pain/temp/crude impaired

after a stroke, how does somatic sensation return

ALS can return to normal d/t c fibers diffuse pain pathway and growth of axon terminal DCML: can not return to normal d/t a beta neurons not regenerating

where does the a delta neurons perceive pain and the function

cortical localize pain conscious awareness/perception

where does the c fiber neurons perceive pain and the function

subcortical- medulla RF, hypothalamus, limbic system diffuse unconscious awareness

what medication can inhibit c fibers

valium decrease unpleasant/care but pain still exit due to a delta