1. The document discusses the anatomy and pathways of the pain sensation system. It describes how nociceptors detect painful stimuli and transmit signals to the spinal cord and brain.
2. The spinal cord plays an important role in pain processing. It contains ascending tracts that carry pain signals to the brain and descending tracts that modulate pain. Key nuclei in the spinal cord dorsal horn relay and modulate pain transmission.
3. Pain signals are transmitted from the spinal cord via the spinothalamic tract to the thalamus and then to regions of the cerebral cortex involved in pain perception and modulation like the somatosensory, cingulate, and insular cortices. The periaqueductal
This document discusses pain pathways in the human body. It begins with definitions of pain from various sources and an overview of the functional anatomy and neurophysiology of pain. It then covers topics like neurochemistry of nociception, theories of pain, pain modulation, types of pain, and factors affecting the pain response. Diagrams are provided to illustrate concepts like nociceptor types and locations, nerve fiber types and velocities, synaptic transmission of pain signals in the dorsal horn and pathways to the brain. The gate control theory of pain and mechanisms of central modulation of pain are also summarized.
This document provides an outline and overview of the neurophysiology of pain. It begins with definitions of pain and discusses the dual nature of pain perception and reaction. It describes the types of pain receptors and the chemical mediators involved in pain signaling. The theories of pain perception including specificity theory, central summation theory, and the gate control theory are summarized. The physiology of pain processing from transduction to transmission and modulation is explained. Assessment scales for pain are also mentioned. The document provides references for further reading on the topic.
This document discusses pain anatomy and physiology. It defines pain as an unpleasant sensory and emotional experience associated with tissue damage. Nociception is the process by which nociceptors detect and transmit signals of potential tissue damage to the brain. There are different types of nociceptors and pain fibers that detect fast, sharp pain or slow, dull pain. The ascending pain pathway involves three neurons that transmit nociceptive signals from receptors to the spinal cord and thalamus. The gate control theory proposes that non-painful input can close the "gates" and inhibit pain transmission.
Pain serves an adaptive purpose by alerting us to potential threats and motivating avoidance. It is both a sensory experience mediated by nociceptors and an emotional one. Pain becomes chronic when it persists beyond healing or when sensitization causes pain in the absence of ongoing tissue damage. Animal models are used to study pain mechanisms and test treatments given pain's complexity. Sensitization occurs peripherally by chemicals released during injury and centrally by neurotransmitters amplifying excitatory signaling in the spinal cord. Descending pathways from the brain can modulate pain transmission both up and down.
1) Pain physiology involves transduction, transmission, perception, and modulation of nociceptive signals from the periphery to the brain.
2) Pain signals are transmitted via Aδ and C nerve fibers to the spinal cord and then to the brain. Aδ fibers transmit fast, sharp pain while C fibers transmit slow, dull pain.
3) Central modulation occurs in the spinal cord and brain and can either facilitate or inhibit pain transmission and perception through mechanisms like windup, sensitization, and the release of neurotransmitters.
Referred pain, also known as reflective pain, is pain perceived in a location other than where the painful stimulus originates. There are several proposed mechanisms to explain referred pain, with the convergence-projection theory being the most widely accepted. This theory suggests that afferent nerve fibers from different structures converge on the same spinal cord neurons, resulting in pain being perceived elsewhere. Other mechanisms like central sensitization may also play a role in referred pain. Certain organs have characteristic referred pain patterns, such as cardiac pain often radiating to the left arm, helping clinicians diagnose conditions.
1) Pain involves complex neurophysiological processes including transduction, transmission, modulation, and perception of pain signals in the peripheral and central nervous systems.
2) Nociceptive fibers detect and transmit noxious stimuli from the periphery to the spinal cord. Transmission involves both myelinated Aδ fibers and unmyelinated C fibers.
3) Modulation of pain occurs both peripherally by inflammatory mediators and centrally through descending inhibitory pathways and neurotransmitters like opioids. Central sensitization in the spinal cord dorsal horn can lead to hyperalgesia and allodynia.
This document provides an overview of pain and pain pathways. It defines pain, discusses the history of pain theories, and describes the different types of pain receptors and neural pathways involved in pain perception and modulation. Specifically, it outlines fast and slow pain pathways conducted by myelinated and unmyelinated fibers, discusses peripheral and central mechanisms of injury-induced pain, and classification of pain including somatic and visceral pain.
The document discusses pain, including its definition, types, perception and pathways. It defines pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. It classifies pain into physiological (nociceptive), pathological (neuropathic), and psychogenic types based on its mechanism or cause. The neural pathways for pain transmission, including the neospinothalamic and paleospinothalamic tracts, are described. The concepts of referred pain and the endogenous analgesia system, including the gate control theory, are also summarized.
The document discusses the physiology of pain. It defines pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage. It describes the dual nature of fast and slow pain mediated by different nerve fiber types. Stimuli that can cause pain and the receptors involved are discussed. The pathways that carry pain signals from receptors to the brain through the spinal cord and thalamus are summarized. Finally, it outlines the gate control theory of pain modulation by interactions between pain and touch fibers at the spinal cord.
Pain pathway gate control theory
Pain management
An unpleasant emotional experience usually initiated by noxious stimulus and transmitted over a specialized neural network to CNS where it is interpreted as such.
1. Exteroceptors: arising from receptors from skin & mucosa. sensed at conscious level
E.g. Merkel corpuscles : Tactile receptors.
Free Nerve ending :Perceive superficial pain.
2. Proprioceptors : From musculoskeletal structures.
The presence , positions & movement of body. below conscious levels.
E.g. 1) Muscle spindles : Skeletal muscle fibers. Mechanoreceptors.
2) Free nerve ending : Perceive deep somatic pain & other sensations.
3. Interoceptors : From viscera of body below conscious level.
E.g. Pacinian corpuscles : perception of touch-pressure.
Free nerve ending : Perceive visceral pain & other sensations.
This document provides an overview of the physiology of pain. It discusses:
1. The definition of pain according to the International Association for the Study of Pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage.
2. The dual nature of pain as either fast, acute pain transmitted by thin myelinated nerve fibers or slow, chronic pain transmitted by unmyelinated nerve fibers.
3. The pathways that carry pain signals from nociceptors to the brain, including nerve fibers entering the spinal cord and traveling via the lateral spinothalamic tract to the thalamus and sensory cortex.
4. Descending pain modulatory pathways from the brainstem that can inhibit pain
The document provides an overview of pain pathways, including definitions, classifications, theories, components, and genetics involved in pain transmission. It discusses the various structures and pathways involved in pain processing, from nociceptors and receptors in tissues, to nerve fibers, neurotransmitters, the spinal cord, brainstem, thalamus, and cortex. Both ascending and descending pain pathways are described. Finally, the document outlines assessment and management approaches for acute and chronic pain.
Physiology of Pain, Characteristic of pain, Basic consideration of nervous system, Pain receptor, Mechanism of pain causation, Theories of pain, Pathways of pain, Pain Receptors
Pain is one of the most commonly experienced symptom . It is often spoken of as a protective mechanism since it is usually manifested when an environmental change occurs that causes injury to responsive tissue
Pain is one of the most commonly experienced symptom . It is often spoken of as a protective mechanism since it is usually manifested when an environmental change occurs that causes injury to responsive tissue
This document discusses the anatomy and physiology of pain. It defines pain and describes its sensory and emotional components. It outlines the neurobiology of pain, including transduction, transmission, modulation, and perception. It discusses nociceptors, sensitization, and the gate control theory of pain. It describes the peripheral and central nervous system pathways involved in pain, including the dorsal horn, ascending pathways, descending modulation, and supraspinal regions. It also discusses complex regional pain syndromes.
The document discusses central sensitization, which is an increased responsiveness of nociceptive neurons in the central nervous system to normal input. During central sensitization, there is an increase in the excitability of nociceptive and wide dynamic range spinal cord neurons. This leads to lower activation thresholds, increased responses to noxious and non-noxious stimuli, and expanded receptive fields. The mechanisms involve the release of neurotransmitters like glutamate and substance P, which activate receptors and intracellular signaling cascades to reduce the activation threshold of dorsal horn neurons.
1. Nociceptive fibers that detect painful stimuli are distinct from other sensory fibers, and can be classified as myelinated A-delta fibers or unmyelinated C fibers.
2. Pain signals travel through two main pathways in the spinal cord - the anterolateral pathway and dorsal column pathway.
3. Pain processing involves peripheral sensitization at the site of injury, and central sensitization in the spinal cord which can amplify pain signaling.
This document discusses pain pathways and mechanisms. It defines pain, outlines the history of pain theories, and describes pain receptors, neurotransmitters, and the dual pain pathways of the neospinothalamic and paleospinothalamic tracts that transmit signals to the brain. It also covers assessment and management of pain, including pharmacological and non-pharmacological approaches.
Pain is a complex physiological process involving nociceptors, nerve fibers that transmit signals to the spinal cord and brain. The perception of pain involves multiple areas of the brain and its experience is influenced by both physiological and psychological factors. Pain signals travel through the neospinothalamic and paleospinothalamic pathways and are modulated by descending inhibitory pathways from the brain. The gate control theory explains how non-painful stimuli can reduce pain perception.
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The nervous system consists of sensory, motor, and higher functional parts. There is continuous information flow between the brain, spinal cord, and peripheral nerves via sensory and motor pathways. The main pathways that carry sensory information are the posterior column pathway, anterolateral pathway, and spinocerebellar pathway. The posterior column pathway carries fine touch, proprioception, vibration and stereognosis sensations via the dorsal column-medial lemniscus tract. The anterolateral pathway carries pain and temperature sensations via the spinothalamic tracts. The spinocerebellar pathway relays proprioceptive information to the cerebellum.
The document summarizes key concepts related to the sensory system and pain perception. It discusses:
- The basic process of sensation from receptor stimulation to brain interpretation
- Adaptation of sensory receptors to continuous stimulation
- Organization and processing of sensory information at the receptor, circuit, and perceptual levels in the somatosensory system
- Ascending pathways that transmit sensory information from receptors to the brain
- Theories of pain perception including specificity, pattern, and gate control theories
- Modulation and inhibition of pain at different levels including presynaptic inhibition and descending pathways from the brain
This document summarizes key aspects of pain pathways and nociception. It discusses the types and causes of pain, the different pain receptors, and their locations. It describes the anterolateral pain pathway, including its subdivisions and functions. It also discusses central processing of somatosensory information in the somatosensory cortex and thalamus, sensory modalities, stimulus discrimination, and the functions of nociceptors.
The document summarizes the pain pathway from peripheral receptors to the brain. It begins with peripheral nociceptors that detect high-threshold stimuli and transmit signals along primary afferent neurons to the spinal cord. In the spinal cord, neurons form ascending tracts that relay the pain signal to the brainstem and thalamus. Thalamic neurons then project to somatosensory cortices for the sensory-discriminative processing of pain. Additional pathways project to areas involved in affective and cognitive processing of pain. Specific examples of pain pathways for the cornea, labor, and caesarean section are also summarized.
The nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS). The CNS contains the brain and spinal cord for integrating and controlling signals, while the PNS uses nerves to connect the CNS to the rest of the body. Neurons are the basic functional units that transmit signals via electrical impulses. Supporting glial cells insulate neurons and provide nutrients. Sensory neurons carry signals to the CNS, while motor neurons carry signals from the CNS to muscles and glands. Reflexes are rapid, involuntary responses mediated by neural pathways and occurring without conscious thought.
nervous system ppt pptx anatomy system of nervesPhebeLois1
The nervous system has two main divisions - the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is made up of the brain and spinal cord, which act as integrative and control centers. The PNS includes nerves that connect the CNS to the rest of the body and transmit sensory information to the CNS and motor commands from the CNS. Neurons are the basic functional units and come in sensory, motor, and interneuron types. Supporting glial cells insulate and protect neurons. The nervous system uses electrical and chemical signals to sense the environment, integrate information, and coordinate responses via pathways like ascending and descending tracts in the spinal cord and reflex arcs.
The document summarizes the key aspects of the autonomic nervous system (ANS). It describes how the ANS is divided into the sympathetic and parasympathetic divisions which work antagonistically to innervate organs like the heart. The sympathetic division prepares the body for fight or flight while the parasympathetic division promotes rest and digestion. The ANS acts involuntarily to maintain homeostasis through dual innervation of target organs and tissues.
1) The document describes several ascending tracts in the spinal cord that transmit sensory information to the brain.
2) The dorsal column-medial lemniscal pathway transmits fine touch, vibration and proprioception while the anterolateral system transmits crude touch, pressure, pain and temperature.
3) Other ascending tracts include the spinotectal, spinoreticular, and spinocerebellar tracts which are involved in visual reflexes, consciousness, deep pain perception and proprioception respectively.
Anatomy of ascending and descending tractsMBBS IMS MSU
The document summarizes the ascending tracts in the spinal cord that convey sensory information from the peripheral nervous system to the brain. It describes the three neuron chain involved in sensory pathways and outlines the major ascending tracts, including the lateral spinothalamic tract for pain and temperature, anterior spinothalamic tract for touch and pressure, and fasciculus gracilis and cuneatus for proprioception, vibration, and discriminative touch. It provides examples of clinical presentations that would result from lesions to different ascending tracts.
Anatomy of ascending and descending tractsMBBS IMS MSU
The document summarizes ascending and descending tracts in the spinal cord that transmit sensory and motor information between the spinal cord and brain. It describes the three neuron chain of ascending tracts that transmit exteroceptive, interoceptive, and proprioceptive sensory information from the peripheral receptors to the brain. It outlines the major ascending tracts - lateral and anterior spinothalamic tracts for pain/temperature and touch/pressure, and the posterior white column and cuneate and gracilis fasciculi for proprioception. It also summarizes the descending motor tracts including the corticospinal, rubrospinal, vestibulospinal, reticulospinal and tectospinal tracts that
This document provides an overview of the nervous system with a focus on the spinal cord. It discusses the anatomy and functions of the spinal cord, including its meninges, cross section, nuclei, tracts, nerves, and plexuses. It also covers spinal cord injuries and the Unani concept of the spinal cord from early Islamic physicians. In summary, the document outlines the key components and functions of the spinal cord, describes its internal structures and surrounding protective layers, and discusses spinal nerve roots and plexuses as well as historic Unani perspectives.
spinal cord, ascending tracts of the the spinal cord, spinocortical tracts, gray matter of spinal cord, white mater of spinal cord, organization of neuron, first order second order and third order neuron, anterolateral spinal tract anteroposterior spinal tract, spinolivary tract, visceral sensory tract, dorsal column tract, spino cerebellar tract , spinorectal pathway, spino olivary pathway, cerebellar peduncles,
The document provides information on the ascending tracts of the spinal cord, which carry sensory information from the periphery to the brain. It discusses the three neuron pathway and lists eight major ascending tracts - the posterior white column tracts (fasciculus gracilis and cuneatus), lateral spinothalamic tract, anterior spinothalamic tract, spinocerebellar tracts, spinotectal tract, spino-olivary tract, and spinoreticular tract. Each tract is described in terms of its origin, course, termination, and function in sensory processing and perception. Lesions to different tracts can result in loss of specific sensory modalities.
The document provides information about the structure and function of neurons and the nervous system. It defines the main parts of a neuron including the soma, dendrites, axon and terminal buttons. It describes how neurons communicate via action potentials and neurotransmitters at synapses. Sensory, motor and interneurons are discussed. The main divisions and structures of the central nervous system are outlined including the forebrain, midbrain and hindbrain. The functions of key structures like the cerebral cortex, limbic system, basal ganglia, thalamus and hypothalamus are summarized.
This document defines pain and discusses its pathophysiology. It notes that pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage. Two major classes of pain are described: normal/nociceptive pain and abnormal/pathophysiologic pain. Nociception involves a complex series of physiological events between tissue damage and pain perception. Nociceptors are activated by mechanical, thermal, and chemical stimuli. The receptors that mediate pain are called nociceptors, which come in two types: Aδ myelinated nerve fibers and C unmyelinated nerve fibers. The neuroanatomy of pain processing involves afferent pathways, the central nervous system, and efferent pathways.
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This document provides an overview of pain management in dentistry. It begins with a brief history of theories of pain and the development of pain receptors. It then discusses the neurophysiology of pain, including transduction, transmission, modulation, and perception of pain signals in the nervous system. The document outlines several theories of pain, including intensity theory, specificity theory, pattern theory, and gate control theory. It also classifies types of pain and reviews both non-pharmacological and pharmacological approaches to pain control and management in clinical settings.
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1. PAIN PATHWAY
ANATOMY
MODERATOR: DR FAREED AHMED
PRESENTED BY:DR ANURADHA
2. Sensation of the affected level of
unpleasantness
Perception of actual or threatened damage
based on past experience, anxiety, cognitive
factors
Pain is Subjective
3. A quality that has complex phenomenological
facets (behavioral, sensory, emotional)
Pain perception can be modulated by all kinds
of factors, including behavioral states
(stress, sex), cognitive states
(hypnosis), mental states (“trance”), social
norms and drugs.
4. Nociceptors are special receptors that respond only
to noxious stimuli and generate nerve impulses
which the brain interprets as “pain”
Free nerve endings
Tissue damage
5. Aδ – fast, sensitive to mechanical noxious
stimuli. – small, myelinated. High
conductance speed
C – slow, sensitive to many noxious stimuli
(chemical, etc.) – small, unmyelinated. Slow
conductance speed
This distinction has been used to explain
the phenomenon of double-pain
7. •Glutamate - Central
Pain •Substance P - Central
Initiators •Brandykinin - Peripheral
•Prostaglandins - Peripheral
•Serotonin
Pain •Endorphins
Inhibitors •Enkephalins
•Dynorphin
8. 1. gray matter
2. white matter
3. gray commissure
4. central canal
Dorsal and ventral nerve
roots
9. Ascending and descending fibers are organized in
distinct bundles which occupy particular areas and
regions in the white matter
Generally long tracts are located peripherally in the white
matter, while shorter tracts are found near the gray
matter
• The TRACT is a bundle of nerve fibers (within CNS) having the same
origin, course, destination & function
• The name of the tract indicates the origin and destination of its fibers
• The axons within each tract are grouped according to the body region
innervated
10. 1. nuclei
2. horns
a. dorsal -- sensory
b. ventral – motor
c. lateral – autonomic
Spinal grey matters divided into 10 layers
11. Tracts that serve to join brain to the spinal
cord
Ascending
Descending
Fibers that interconnect adjacent or distant
segments of the spinal cord
Intersegmental (propriospinal)
12. Three major pathways carry sensory information
Posterior column pathway (gracile & cuneate
fasciculi)
Anterolateral pathway (spinothalamic)
Spinocerebellar pathway
13. Monitor conditions both inside the body and in the
external environment
Sensation-stimulated receptor passes information
to the CNS via afferent (sensory) fibers
Most sensory information is processed in the spinal
cord , thalamus, or brain stem. Only 1% reaches
the cerebral cortex and our conscious awareness
Processing in the spinal cord can produce a rapid
motor response (stretch reflex)
Processing within the brain stem may result in
complex motor activities (positional changes in the
eye, head, trunk)
14. THREE neurons from the
receptor to the cerebral cortex
First order neuron:
Cell body located in the dorsal 3
root ganglion. The Axon (central
process) passes to the spinal
cord through the dorsal root of
spinal nerve gives many
collaterals which take part in
spinal cord reflexes runs 2
ipsilaterally and synapses with
second-order neurons in the
cord and medulla oblongata 1
15. Second order neuron:
◦ Has cell body in the
spinal cord or medulla
oblongata
◦ Axon decussate &
◦ Terminate on 3rd order
neuron
Third order neuron:
◦ Has cell body in
thalamus
◦ Axon terminates on
cerebral cortex
ipsilaterally
16. DIRECT---- direct conscious appreciation of
pain
INDIRECT---affective or arousal impact of
pain via
1) Spino-reticular-thalamic –cortical pathway
(ARAS)
2) Spino-mesencephelic path (affective impact
of pain)
17. Pain information
travels up the spinal
cord through the
spinothalamic track
(2 parts)
•Immediate warning of the
ANTERIOR/VENTRAL presence, location, and
intensity of an injury
•Slow, aching reminder that
LATERAL tissue damage has occurred
Decussates at the
level of spinal
cord
18. Descending pain
pathway
responsible for
pain inhibition
“affective
sensation”i.e
compulsion to act
19. Located lateral and ventral to
the ventral horn
Carry impulses concerned
with pain and thermal
sensations (lateral tract) and
also non- discriminative
touch and pressure (medial
tract)
Fibers of the two tracts are
intermingled to some extent
In brain stem, constitute the
spinal lemniscus
Fibers are highly somato-
topically arranged, with
Information is sent to
those for the lower limb lying the primary sensory
most superficially and those
for the upper limb lying cortex on the opposite
deeply side of the body
20. Axons of 1st order neurons
terminate in the dorsal horn
Axons of 2nd order neuron
(mostly in the nucleus
proprius), decussate within
one segment of their origin, by
passing through the ventral
white commissure & terminate
on 3rd order neurons in ventral
posterior nucleus of the
thalamus
Thalamic neurons project to
the somatosensory cortex
21. SKIN
SPINAL CORD via pseudounipolar cells
SUBSTANTIA GELATINOSA OR NUCLEUS PROPRIUS via LISSAUER TRACT
CROSS OVER VIA ANTERIOR COMMISURE
BRAIN STEM (ROSTRAL VENTROMEDIAL MEDULLA)
THALAMUS (VPL,VPM,MEDIAL DORSAL)
CINGULATE CORTEX,SOMATOSENSORY CORTEX AND INSULAR CORTEX
22. Pseudounipolar cell (dorsal
root ganglion) ,divides
into central and
peripheral branch)
Head and neck,carried by
5/6/9/10 via gasserian
ganglion,geniculate,super
ior and inferior
petrosal nerve,jugular
ganglion(somatic) and
ganglion nodosum
(viseral)
Reach brain stem via
cranial nerves
23. Tip of the posterior
column near posterior
nerve roots
Centrally projecting
axons carrying
discriminating pain
/temperature info
regarding
location/intensity/qu
ality
Synapse with second
order neuron,crosses
midline and joins STT
24. SUBSTANTIA GELATINOSA:
grey horn wid gelatinous
sub which contains
neuroglia and nerve cells
Rexed lamina 2
Contains opiod
receptors/ c fibres and
a-delta fibres
NUCLEUS PROPRIUS
Bulk of dorsal horn
Rexed 3/4/5
a/w fine touch and
pressure with nucleus
dorsalis
25. Lamina of Rexed
Lamina I ---------- marginal layer
Lamina II ---------- substantia gelatinosa of Rolando
Lamina III, IV ----- nucleus proprius
Lamina V, VI
Lamina VII --------- intermediate gray
intermediolateral cell column (ILM)
Clarke’s column (Nucleus dorsalis)
intermediomedial cell column (IMM)
Lamina VIII----------motor horn
Lamina IX ---------- anterior horn (motor) cell
Lamina X ----------- gray commissure
26. ANTERIOR WHITE COMMISURE
alba anterior medullae spinalis
just anterior to the gray
commissure (Rexed lamina X).
A δ fibers and C fibers
ROSTRAL VENTROMEDIAL
MEDULLA
midline on the floor of the
medulla (myelencephalon
sends descending inhibitory and
excitatory fibers to the dorsal
horn spinal cord neurons
On-cells, off-cells, and neutral
cells.
important in the maintenance of
neuropathic pain
RVM contains high levels of both
the neurokinin 1 receptor and its
endogenous ligand, Substance P
(SP).
28. Sensory aspects of pain seem to be processed in the
Somatosensory cortex.
Emotional distress associated with pain seems to be
processed in the Anterior Cingulate Cortex (ACC).
Subjects with lesions in ACC could still accurately
judge the intensity of pain. But they were not in the
least bothered by it.
• On the other
hand, subjects empathy
for the pain of others
only elicits activity in
ACC, not Somatosensory
cortex.
29. CINGULATE CORTEX
the medial aspect of the
cortex
Part of limbic lobe
Receives input from
thalamus and neocortex
PRIMARY SOMATOSENSORY
CORTEX
30. INSULAR
CORTEX
deep within the
lateral sulcus
the fissure
separating the
temporal and
the frontal
lobes
linked to
emotion
Associated with
addiction
31. gray matter located around the cerebral
aqueduct within the tegmentum of the
midbrain.
role in the descending modulation of pain
and in defensive behaviour.
enkephalin-releasing neurons
5-HT (serotonin) released from the raphe
nuclei descends to the dorsal horn of the
spinal cord where it forms excitatory
connections with the "inhibitory
interneurons" located in Laminae II (aka
the substantia gelatinosa).
When activated, these interneurons
release either enkephalin or dynorphin
which bind to mu opioid receptors
32. Melzack & Wall (1965)
A gate, where pain
impulses can be “gated” descending nerve
fibers from brain
The synaptic junctions
between the peripheral
nociceptor fiber and the
dorsal horn cells in the
spinal cord are the sites
of considerable
plasticity. pain pathways
axons from
touch
receptors
axons from
“THE PAIN GATE” nociceptors
opioid-releasing
interneuron
33. Stimulation of touch fibres for pain relief:
◦ TENS (transcutaneous electrical nerve stimulation)
◦ Acupuncture
◦ Massage
Release of natural opioids
◦ Hypnosis
◦ Natural childbirth techniques
34. MEDIAL SPINOTHALAMIC TRACT:
MEDIAL THALAMUS
MEDIATES AUTONOMIC AND UNPLEASANT
PERCEPTION OF PAIN PATHWAY
FEW TO PERIAQUEDUCTAL GRAY
COLLATERAL FIBRES TO RAS AND
HYPOTHALAMUS-AROUSAL TO PAIN
35. ran additional route by which dull, aching pain is
transmitted to a conscious level
Some 2nd order neurons terminate in the reticular
formation of the brain stem, mainly within the
medulla
Reticulothalamic fibers ascend to intralaminar nuclei
of thalamus, which in turn activate the cerebral
cortex
36. Located in
periaqueductal grey
matter of the
brainstem,amygdala,
corpus striatum nd
hypothalamus
Spinal
cord(substance
gelatinosa)
Endorphins inhibit
release of excitatory
neurotransmitters
37. Mu,kappa and delta
Superfamily of G protein
coupled receptors
Brain,spinal cord and
peripheral recetors
Mimic endogenous ligands
l/t hyperpolarisation
38. • Pain receptors are the only receptors in viscera whose stimulation produces
sensations
• Pain receptors respond differently to stimulation
• Pain receptors are not well localized
• Pain receptors may feel as if coming from some other part of the body
• Known as referred pain…
38
39. Afferent innervation of the viscera.
Often anatomical separation nociceptive innervation (in
sympathetic nerves) from non-nociceptive
(predominantly in vagus).
Many visceral afferents are specialized nociceptors, as
in other tissues small (Ad and C) fibers involved.
Large numbers of silent/sleeping nociceptors, awakened
by inflammation.
Nociceptor sensitization well developed in all visceral
nociceptors.
40. Pain originating
from organs
perceived as
coming from skin
Site of pain may be
distant from organ
41. Referred pain
Convergence theory:
This type of referred pain occurs
because both visceral and somatic
afferents often converge on the same
interneurons in the pain pathways.
Excitation of the somatic afferent
fibers is the more usual source of
afferent discharge,
so we “refer” the location of visceral
receptor activation to the somatic
source even though in the case of
visceral pain.
The perception is incorrect. The convergence of
nociceptor input from the
viscera and the skin.
42. • Thalamus
• Allows person to be aware of pain
• Cerebral cortex
• Judges intensity of pain
• Locates source of pain
• Produces emotional and motor responses to pain
• Pain inhibiting substances:
• Enkephalins
• Serotonin
• Endorphins
42
43. Left
spinothalamic pathway spinal cord injury
. Anaesthesia will normally
Loss of sense of: begin 1-2 segments below
•Touch the level of
•Pain
•Warmth/cold lesion, affecting all caudal
in right leg body areas.
44. Hyperalgesia:
The skin, joints, or muscles that have already
been damaged are unusually sensitive. A light
touch to a damaged area may elicit excruciating
pain;
Primary hyperalgesia occurs within the area of
damaged tissue;
Secondary hyperalgesia occurs within the
tissues surrounding a damaged area.
45. Melzack (1992) 7 features
1. Phantom limb feels real. Sometimes amputees try
to walk on their phantom limb.
2. brain contains neuromatrix of the body image –
neurosignature like a hologram
46. A well-known case of congenital insensitivity
to pain is a girl referred to as 'miss C' who
was a student at McGill university in Montreal
in the 1950s.
She was normal in every way, except that she
could not feel pain. When she was a child she
had bitten off the tip of her tongue and had
suffered third-degree burns by kneeling on a
radiator.
47. Aspirin and ibuprofen block formation of
prostaglandins that stimulate nociceptors
Novocain blocks conduction of nerve
impulses along pain fibers
Morphine lessen the perception of pain in
the brain.
48. 1. Prevents serious damage. If you touch
something hot, you are forced to withdraw
your hand before it gets seriously burnt.
2. Teaches one what to avoid
3. If pain is in joints, pain limits the activity, so
no permanent damage can occur.
but pain can become the problem, and
cause people to want to die.