Pain

Question 1

Pain

Answer 1

A perception, not a stimulus, has no definitive physical dimensions
Most modifiable system of the body
Sensory experience evoked by stimuli that injure or threaten to injure tissue

Question 2

Reticular formation

Answer 2

Makes up central core of brainstem, characterized by aggregations of cells of different types and sizes, interspersed with wealth of nerve fibers traveling in many directions and excludes organized groups of cells

Question 3

Allodynia

Answer 3

Normally non-nociceptive stimulus is painful

Question 4

Perception of event

Answer 4

Consciousness via cerebral cortex -> loss of reflex doesn’t correlate to a loss of pain perception

Question 5

Conditions producing absences of nociceptive reflex

Answer 5

Lost afferent supply to region where noxious stimulus is applied
Damage to spinal cord segment mediating reflex
Lost efferent supply to limb flexors
Trauma, peripheral neuropathies
Myoneural transmission blockage
Hyperreflexic nociceptive reflexes if spinal cord is damaged cranial to limb tested

Question 6

Total loss of pain response to deep pain stimuli

Answer 6

Serious, irreversible damage to spinal cord

Question 7

Reflex arcs

Answer 7

Involve multisynaptic excitation of ipsilateral flexor LMNs and inhibition of ipsilateral extensor LMNs
If standing, elicitation of nociceptive reflex in one limb results in contralateral extension reflex (doesn’t happen in recumbency)

Question 8

Medial spinothalamic pathway

Answer 8

Located ventromedially
Ipsilateral and bilateral components, motivational afferent pathway
Supraspinal destination: medullary reticular formation and midline and intralaminar nuclei

Question 9

Spinoreticular pathway

Answer 9

Located ventromedially, just lateral to propriospinal pathway
Supraspinal destination: medullary and pontine reticular formations, terminate in nuclei of medullary RF or project rostrally to medial and intralaminar thalamic nuuclei

Question 10

Medial system

Answer 10

Conducts impulses arising from stimuli that have produced actual damage to animal
Motivational affective dimensions of pain sensation
Terminate almost exclusively in intralaminar and midline nuclei in reticular formation

Question 11

Cerebral cortex involvement in nociception

Answer 11

No specific area uniquely responsible for perception of pain

Nociceptive pathways project to midline, intralaminar, and ventral thalamic nuclei

Question 12

Diencephalon involvement in nociception

Answer 12

Serves as relay for most activity entering cerebral cortex from pathways originating in brainstem and spinal cord, with exception of olfactory system

Question 13

Mesencephalon involvement in nociception

Answer 13

Electrical microstimulation produces profound state of analgesia

Question 14

Medullary and pontine reticular formation

Answer 14

nociceptive input

Question 15

Acute pain

Answer 15

Brief, usually elicits avoidance behavior

Question 16

Nociceptors

Answer 16

Receptors involved in pain, respond to noxious stimuli
Free nerve endings in skin and viscera
Terminal ending of peripheral process of a nociceptive fiber that conducts in A-delta and C fiber conduction velocity range
Afferents terminate in superficial layers of dorsal horn

Question 17

Noxious stimuli

Answer 17

Strong mechanical pressure, heat, excessive cold, chemical substances, high electrical stimulation

Question 18

Sensory-discriminative dimension

Answer 18

Addresses questions of where, what, how rapidly

Question 19

Motivation-affective dimension

Answer 19

Addresses how to avoid stimulus and how sever is the injury

Question 20

Fast superficial pain

Answer 20

First pain, sharp, pricking

Signaled by myelinated A-delta fibers

Question 21

Slow superficial pain

Answer 21

Second pain, aching, burning, deep pain

Signaled by unmyelinated C nociceptor fibers

Question 22

Chronic pain

Answer 22

Lasts longer (months-years) and usually associated with suppression of activity and depression
Can alter other pathways, sensitivity, hormonal balance, etc.

Question 23

Spinocervicothalamic pathway

Answer 23

Ascends in dorsal part of lateral funiculus
Responds to noxious thermal and mechanical stimulation and fibers responding to low-threshold mechanical stimulation
Supraspinal destination: central and caudal part of VPL of thalamus

Question 24

Dorsal column-postsynaptic pathway

Answer 24

Located just medial to dorsal horn
Bilateral pathway, carries info from visceral structures
Supraspinal destination: VCL of thalamus

Question 25

Propriospinal pathway

Answer 25

Located just lateral to ventral horn | Supraspinal destination: medullary and pontine reticular formation

Question 26

Nociceptive reflex behavior

Answer 26

Withdrawal reflex Involves flexion of limb Involve at least 3 spinal cord reflexes and many simultaneously acting reflex mechanisms Only dependent integrity of reflex arc

Question 27

Pain perception

Answer 27

Voluntary act by which an animal demonstrates that it has perceived a noxious stimulus as painful (cerebral cortex) Requires integrity of afferent fibers and ascending and descending pathways

Question 28

Criteria used to determine whether a given stimulus gives rise to pain or whether animal is showing non-perception linked reflexes

Answer 28

Stimulus, in normal animal, must be perceived as pain Stimulus must threaten or actually destroy tissue Animal must show aversive response to stimulus Injury to CNS to drugs used, cerebral cortex must be in a state in which perception can occur (tests include menace visual placing, tactile placing, conscious proprioception, EEG)

Question 29

Nociceptor threshold

Answer 29

Minimum noxious stimuli required to generate nerve impulses in a nociceptor

Question 30

Pain-detection threshold

Answer 30

Minimum noxious stimulus applied that gives rise to the perception of pain Emphasizes discrimination of nociceptive quality Varies with stress and anxiety

Question 31

Pain-tolerance threshold

Answer 31

Maximum noxious stimulus tolerated under experimental conditions Expression of willingness to receive more intense stimulation

Question 32

Lateral system

Answer 32

Conducts impulses that lead to perceptions about precise location, qualitative nature and areal extent of stimulus Terminate predominantly in lateral group of nuclei (VPM, VPL, VL, POM)

Question 33

Lateral spinothalamic pathway

Answer 33

Located ventrolaterally Ipsilateral and bilateral components, sensory discriminative pathway Supraspinal destination: VPL, VL, and intralaminar nuclei of thalamus

Question 34

Pain-sensitivity range

Answer 34

Difference between the pain-detection threshold and the pain-tolerance threshold