Neuro L14 Pain/temp Pathways

Front 1

Receptors of the pain pathways

Back 1

non-encapsulated, free nerve endings
Nociceptors:
-associated with Asigma Fibers = FAST PAIN (localized, sharp)
-accociated with C fibers = SLOW PAIN (dull, throbbing)

Front 2

Receptors of temperature pathways

Back 2

Heat Receptors
Cold Receptors
likely some warming/cooling also
free nerve endings

Front 3

pain and temperature information travels on what pathways?

Back 3

ANTEROLATERAL SYSTEM (aka spinalthalamic) (**for MOST of the body)

TRIGEMINAL PAIN AND TEMPERATURE SYSTEM (for anterior 2/3 of head)

Front 4

How do pain and temp fibers of CNVII, IX and X reach cortex?

Back 4

cell bodies located in sensory ganglia associated with CNs (geniculate (VII), superior of (IX and X)) and central axon enters trigeminal pain and temperature system (in spinal tract of CNV)

Front 5

ANTEROLATERAL SYSTEM is a pathway for what type of information?

Back 5

PAIN/
TEMPERATURE/
CRUDE(light) touch

Front 6

Describe path of pain in leg

Back 6

1st Order: Nocireceptor, peripheral nerve, cell body in DRG, enters dorsal root, ascends DORSOLATERAL TRACT OF LISSAUER, synapses in dorsal horn (directly or indirectly)
2nd Order: decussate via anterior commissure, ascend to thalamus in STT, most synapse in VPL nucleus
3rd order: project through posterior limb of the internal capsule to the SI

Front 7

Describe synapse between first and second order neurons of ALS Pathway

Back 7

direct synapse at neurons of:
-Marginal zone or
-Substantia Gelatinosa

Indirect synapse in neurons of: -Lamina V
(via interneurons from substantia Gelatinosa)

Front 8

where do fibers decussate in ALS Pathway

Back 8

in the anterior white commissure of the spinal cord

Front 9

where are the synapses in the ALS pathway?

Back 9

1-->2 (DORSAL HORN: Marginal, Substania Gealtinosa or Lamina V)

2-->3 (mostly in VPL Nucleus of the Thalamus, some project elsewhere: involved in general arousal/emotional response)

3-->cortex (SI)

Front 10

within the brainstem where are pain/temp fibers from the legs found?

Back 10

in the lateral part of the SPINOTHALAMIC TRACT (stay lateral, but swing anteriorly as they ascend rostrally)

Front 11

Explain basis for referred pain

Back 11

afferent nociceptors from viscera, CONVERGE on same 2nd order cell bodies (of the ALS) as cutaneous nociceptors

brain cannot distinguish source of pain, often assumes cutaneous (much more frequent source of input, than viscera)

Front 12

describe pathway of TRUE VISCERAL PAIN (as opposed to referred)

Back 12

true visceral pain travels from nociceptors of viscera to synapse with 2nd order cell bodies in intermediate gray matter near the central canal that travel in the DC-ML
(these fibers conduct actual visceral pain sensations)

Front 13

neurons in the pain-modulating pathways use what as neurotransmitters?

Back 13

endogenous opiate peptides (enkephalins, endorphins, and dynorphins)

explains why opium derivatives are ANALGESTIC, mimic neurotransmitters thereby activating pain-modulating pathways

Front 14

GATE THEORY OF PAIN

Back 14

mechanosensory fibers (Aa and Ab) traveling with the smaller pain fibers (Ad and C) in the
dorsal roots. It is thought that when the large fibers are stimulated, they stimulate inhibitory interneurons in the dorsal horn
(why you rub/shake injured hand)

Front 15

Damage to the STT will impair

Back 15

pain, tempearture and touch ability, however fine touch would still be intact via the DC-ML system

Front 16

Describe deficit if the ventrolateral column fibers are damaged on one side of the spinal cord (as in Brown-Sequard syndrome)

Back 16

the sensory deficit will be contralateral inferior to the level of the v If the ventral part of the spinal cord is damaged (as in syringomyelia*), the anterior white commissure can be disrupted. This results in lesion (sometimes as many as 4-6 segments inferior to the lesion due to neurons traveling up the tract of Lissauer).

Front 17

If the ventral part of the spinal cord is damaged (as in syringomyelia*), the anterior white commissure can be disrupted. This results in

Back 17

bilateral loss of pain and temperature in the areas of the body that are supplied by the damaged segments. The resulting pattern of sensory loss is called suspended-dissociated loss (“suspended” because the area of the deficit is between two intact areas, and “dissociated” because only pain and temperature information is affected).

Front 18

If a lesion occurs in the cerebral cortex, what sensory loss occurs?

Back 18

all sensory modalities are lost except the perception of pain; localization of pain is lost. Therefore, it is thought the conscious perception of pain is mediated at subcortical levels, while localization of pain requires cortical input.

Front 19

Crude touch is assessed by

Back 19

lightly stroking the skin with a piece of cotton. The patient should be able to locate where the sensation is felt.

Front 20

Pain is assessed by

Back 20

applying a sharp object to the patients skin (pin prick) or pinching an area of skin (e.g. with forceps). The patient should be able to describe the quality of the sensation (sharp, dull) and its location.