summary of nervous system, including peripheral nervous system and central nervous system, a brief on nerve anatomy and functioning,gate control theory, mechanism of dental pain

3. CONTENTS
NERVOUS SYSTEM
 Introduction
 Organisation
 Nervous tissue
 Nerve conduction
 Central nervous system
Brain
spinal cord
 Peripheral nervous system
Autonomic nervous system
3

4. CONTENTS
MECHANISM OF PAIN
 Introduction
 Theories
 Pain receptors
 Mechanism of pain in orofacial region
 Descending inhibitory controls
 Endogenous antinociceptive system
 Biochemical basis of nociception
 Sensitization
 Mechanism of dental pain
4

5. NERVOUS SYSTEM
The nervous system is a complex network
that allows an organism to communicate with
its environment
FUNCTIONS
 Respond to external and internal stimuli
 Transmit nerve impulses
 Interpret nerve impulses
 Assimilate experiences in memory & learning
 Initiate glandular & muscle contraction
 Program instinctual behavior
Guyton AC, Hall JE. Organisation of the nervous system, Basic functions of synapses and Neurotransmittors. Textbook of medical physiology.
10th ed. Philadelphia: Saunders; 2006. p.543-582 5

6. NERVOUS SYSTEM
Nervous system is the control and
communication system of the body
Sensory components
Motor components
Integrative components
Detects changes in environment
and stimuli
Generates movement,
contraction of cardiac & smooth
muscle, glandular secretions
Receives, stores and process info
and determine motor response
Guyton AC, Hall JE. Organisation of the nervous system, Basic functions of synapses and Neurotransmittors. Textbook of medical physiology.
10th ed. Philadelphia: Saunders; 2006. p.543-582 6

7. NERVOUS SYSTEM
ORGANISATION
CNS
BRAIN SPINAL CORD
PNS
CRANIAL NERVES SPINAL NERVES
SENSORY NERVES MOTOR FIBRES
ANS SOMATIC SYSTEM
SYMPATHETIC PARASYMPATHETIC
Scully C, Cawson R. Neurological disorders. Medical problems in dentistry. 5th ed. New delhi: Elsivier; 2005. p 296. 7

8. NERVOUS SYSTEM
ORGANISATION
Sherwood L. The central nervous system. From cells to systems. 7th ed. USA: Brooks Cole; 2010. p.133-182 5

9. NERVOUS SYSTEM
NERVOUS
TISSUE
Consists of mainly two types of cells
NEURONS
NEUROGLIA
 Highly specialized to
conduct impulses called
action potentials
 Primary function to
support and assist
neurons
 5 times as abundant as
neurons
 Mitotic capability
Van De Graaf KM, Rhees RW. Nervous tissue. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.65-71
9

10. NERVOUS SYSTEM
NERVOUS
TISSUE
A cord like structure that conveys
nervous impulses
EPINEURIUM – Connective
tissue sheath that
encloses several bundles
of nerve fibers
PERINEURIUM –
Connective tissue sheath
that surrounds each
bundle of nerve fibers
ENDONEURIUM –
Interstitial connective
tissue that separates each
bundle of nerve fibres
NERVE
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
10

11. NERVOUS SYSTEM
NERVOUS
TISSUE
NERVE
AXON
MYELIN SHEATH
PERINEURIUM
NERVE
EPINEURIUM
BLOOD VESSELS
NERVE FASCICLE
(Many axons bundled
in connective tissue)
CONNECTIVE TISSUE
AROUND AXON
Sherwood L. The central nervous system. From cells to systems. 7th ed. USA: Brooks Cole; 2010. p.133-182 11

12. NERVOUS SYSTEM
NERVOUS
TISSUE
The structural unit of nervous system
NERVE CELL BODY – Mass of
protoplasm which contains
NUCLEUS
DENDRITE – A branched
arborizing process that conducts
impulses towards cell body
AXON – central core that
conducts nerve impulses away
from cell body to another neuron
or organ
NEURON
MYELIN SHEATH – layer of fatty
nerve tissue that wrap around some
fibers
NODES OF RANVIER –
constrictions that occur between
intervals of myelinations
AXON TERMINALS – slight
enlargements at the ends of the
axons containing synaptic vesicles
which in turn contain
neurotransmittor
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
12

13. NERVOUS SYSTEM
BASED ON PRESENCE AND ABSENCE OF MYELINATION
MYELINATED NEURONS – White nerves
UNMYELINATED NEURONS – grey nerves
BASED ON NUMBER OF AXONS
UNIPOLAR -Peripheral sensory neurons in which only one
protoplasmic process extends from the cell body
MULTIPOLAR - possesses a single (usually long) axon and many
dendrites. Constitute the majority of neurons in the
brain and include motor neurons and interneurons.
BIPOLAR - Has two extensions. specialized sensory neurons for the
transmission of special senses.
BASED ON LOCATION ANDFUNCTION
AFFERENT NEURON/ SENSORY NEURONS – Transmits impulses to the CNS
EFFERENT NEURON/MOTOR NEURONS – Transmits impulses away from CNS
INTERNEURON/ ASOSCIATION NEURONS – Transmits impulses from motor to
sensory neurons
NERVOUS
TISSUE
NEURO
N
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
13

14. NERVOUS SYSTEM
NERVOUS
TISSUE
NEURO
NTYPE SIZE VELOCITY
TYPE A FIBRES
ALPHA
BETA
GAMMA
DELTA
TYPE B FIBRES
TYPE C FIBRES
13-22 μm
8-13μm
4-8μm
1-4μm
1-3μm
0.5-1μm
70-120m/sec
40-70m/sec
15-40m/sec
5-15m/secc
1-3m/sec
0.5-2m/sec
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
14

15. NERVOUS SYSTEM
NERVOUS
TISSUE
NEURON
CNS PNS
EFFECTOR
ORGAN
AFFERENT
INTERNEURON
EFFERENT
Sherwood L. The central nervous system. From cells to systems. 7th ed. USA: Brooks Cole; 2010. p.133-182 15

16. NERVOUS SYSTEM
NERVOUS
TISSUE
NEURON
DENDRITES
NUCLEUS
MYELIN SHEATH
SCHWANN
CELL
AXON TERMINALS
AXON
NEUROBIBRILS
CELL BODY
CHROMATOPHILLIC
SUBSTANCE
NODE
.
Van De Graaf KM, Rhees RW. Nervous tissue. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.65-71
16

17. NERVOUS SYSTEM
NERVOUS
TISSUE
NEURON
NODES OF
RANVIER MYELIN SHEATH
AXON OF NEURON
MYELIN SHEATH
AXON
PLASMA MEMBRANE
SHWANN
CELL
Sherwood L. The central nervous system. From cells to systems. 7th ed. USA: Brooks Cole; 2010. p.133-182 17

18. NERVOUS SYSTEM
NERVOUS
TISSUE
NEUROGL
IA
EPENDYMAL CELLS
ASTROCYTES
OLIGODENDROCYTES
MICROGLIA
SATELLITE CELLS
NEROLEMMOCYTES
CNS
PNS
Van De Graaf KM, Rhees RW. Nervous tissue. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.65-71
18

19. NERVOUS SYSTEM
NERVE
CONDUCTION
 A self propagated passage of an electric current along nerve
fibers
 Depends on an electric potential that exists across the nerve
membrane
RESTING STATE
DEPOLARIZATION
REPOLARIZATION
MEMBRANE POTENTIAL DEVELOPS BY :
 AN ACTIVE DIFFUSION OF IONS THROUGH MEMBRANE
 PASSIVE DIFFUSION OF IONS BECAUSE OF GRADIENT DIFFERENCE
SYNAPSE & SYNAPTIC
TRANSMISSION
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 19

20. NERVE CONDUCTION
 Inside electrically negative relative to outside
 Anions present inside cell membrane, cations present outside membrane
 Relative permeability of cell membrane to K and relative impermeability to Na
 K ions freely permeable, retained inside by negatively charged nerve membrane
 Cl ions remains outside nerve membrane - opposing electrostatic influence
 Na pumps move Na ions from area of lesser concentration inside the nerve to
area of greater concentration outside
RESTING
STATE
Neuron axon
+ + + + + + + + + +
K +
Na
pump
Cl
_
Na+
Na
+
Na
+
K +
K+K +
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 20

21. NERVE CONDUCTION
DEPOLARIZAT
ION
STIMULUS OF SUFFICIENT
INTENSITY
DISPLACEMENT OF Ca IONS
FROM PHOSPHOLID BINDING
SITES
INITIATION OF CHANGES IN
MEMBRANE PERMEABILITY TO
SODIUM
INCREASE IN DIFFUSION OF Na
IONS INTO CELL
PASSAGE OF K IONS
OUT OF CELL
REVERSAL OF POLARITY
OUTSIDE NEGETIVE
RELATIVE TO INSIDE
Na
DEPOLARIZED INACTIVEINACTIVE
Sherwood L. Principles of neural and hormonal communication. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 21

22. NERVE CONDUCTION
DEPOLARIZAT
ION
INACTIVE
ORIGINAL
ACTIVE AREA
PREVIOUSLY
INACTIVE AREA
DEPOLARISED
PREVIOUSLY
INACTIVE AREA
DEPOLARISED
Na
Sherwood L. Principles of neural and hormonal communication. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 22

23. NERVE CONDUCTION
DEPOLARIZAT
ION
 Passage of impulse is a result
of a continuing stimulation
or chain reaction
 Each area generates its own
action potential
 In myelinated nerves
stimulation only in nodes of
ranvier
SALTATORY CONDUCTION
SALTATORY CONDUCTION
Sherwood L. Principles of neural and hormonal communication. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
23

24. NERVE CONDUCTION
DEPOLARIZAT
ION
ALL OR NONE LAW
RELATIVE
REFRACTORY
PERIOD
ABSOLUTE
REFRACTORY
PERIOD
A THRESHOLD STIMULUS EVOKES A MAXIMAL
RESPONSE: A SUBTHRESHOLD STIMULUS EVOKES
NO RESPONSE
INTERVAL DURING WHICH A SECOND ACTION
POTENTIAL CANNOT BE INITIATED, NO MATTER
HOW LARGE A STIMULUS IS APPLIED
INTERVAL IMMEDIATELY FOLLOWING ABSOLUTE
REFRACTORY PERIOD DURING WHICH INITIATION
OF A SECOND ACTION POTENTIAL IS INHIBITED BUT
NOT IMPOSSIBLE.
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 24

25. NERVE CONDUCTION
REPOLARIZAT
ION
FOLLOWING DEPOLARIZATION
PERMEABILITY OF NERVE
MEMBRANE TO Na DECREASES, K
INCREASES
Na PUMP ACTIVELY TRANSPORTS
Na OUT OF CELL AGAINST CONC
GRADIENT
TRANSPORT OF POTASSIUM INTO
CELL
RESTORATION OF RESTING
POTENTIAL
CHANGES IN MEMBRANE POTENTIAL DURING AP
Sherwood L. Principles of neural and hormonal communication. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 25

26. NERVE CONDUCTION
SYNAPSE &
SYNAPTIC
TRANSMISSION
ACTION POTENTIAL REACHES AXON
TERMINAL
INFLUX OF Ca IONS CAUSES SYNAPTIC
VESICLES CONTAINING NEUROTRANSMITTOR
TO FUSE WITH PRESYNAPTIC MEMBRANE
NEUROTRANSMITTOR DIFFUSES ACROSS
CLEFT TO POST SYNAPTIC MEMBRANE &
BIND WITH SPECIFIC RECEPTORS
NEUROTRANSMITTOR RELEASED BY
EXOCYTOSIS INTO SYNAPTIC CLEFT
NEUROTRANSMITTOR IS REMOVED
FROM SYNAPSE
AXON TERMINAL
PRE
SYNAPTIC
VESICLE
CLEFT
POST SYNAPTIC MEMBRANE
VESICLE
NEUROTRANSMITTOR
RECEPTORS
 EXCITATORY NEUROTRANSMITTOR – EXCITATORY
POST SYNAPTIC POTENTIAL
 INHIBITORY NEUROTRANSMITTOR – INHIBITORY
POST SYNAPTIC POTENTIAL
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
Van De Graaf KM, Rhees RW. Nervous tissue. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.65-71 26

27. NERVE CONDUCTION
SYNAPSE &
SYNAPTIC
TRANSMISSION
CONVERGENCE
SUMMATION
FACILITATION &
INHIBITION
SYNAPSING OF A NEURON WITH SEVERAL OTHERS
CUMULATIVE EFFECT AT A SYNAPSE
INTENSIFICATION OF A RESONSE
SUPPRESSION OF A RESPONSE
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
27

28. CENTRAL NERVOUS SYSTEM
 Brain + Spinal cord
 Contains grey matter & white matter
NERVE CELL BODIES & DENDRITES
UNMYELINATED AXONS &
NEUROGLIA
MYELINATED AXONS
Outer part of cerebrum &
cerebellum
Inner part of spinal cord
Inner part of cerebrum &
cerebellum
Outer part of spinal cord
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.72-78
28

29. CENTRAL NERVOUS SYSTEMBRAIN
There are five regions of brain
TELENCEPHALON
Cerebrum, limbic
structures, basal ganglia
DIENCEPHALON
Thalamus, Hypothalamus,
Pituitary
MESENCEPHALON
Superior and inferior
colliculi, Cerebral
peduncles
MYELENCEPHALON
Medulla Oblongata
METENCEPHALON
Cerebellum, Pons
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.72-78
29

30. CENTRAL NERVOUS SYSTEMBRAIN
CEREBRU
M
CORPUS CALLOSUM
CEREBRAL HEMISPHERE
CEREBRAL CORTEX
CEREBRAL MEDULLA
SULCI & GYRI
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 30

31. CENTRAL NERVOUS SYSTEMBRAIN
CEREBRU
M
FRONTAL LOBE: voluntary control
of skeletal muscle, personality,
intellectual process, verbal
communication
PARIETAL LOBE: cutaneous and
muscular sensation, understanding
and utterance of speech
OCCIPITAL LOBE: Interpretation of
auditory sensation, auditory and
visual memory
TEMPORAL LOBE: Integration of
movements focusing eyes,
correlation of visual images with
experiences, conscious seeing
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 31

32. CENTRAL NERVOUS SYSTEMBRAIN
Control emotional and
behavioral activities
Includes Amygdala,
hippocampus
Control gross body
movements
BASAL GANGLIA
LIMBIC
STRUCTURES
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.72-78 32

33. CENTRAL NERVOUS SYSTEMBRAIN
Paired organ, relay center
for all sensory impulses
except smell to cerebral
cortex
cardiovascular & body
temperature regulation,
water & electrolyte balance,
hunger, sleeping,
wakefulness, emotions,
endocrine functions
(anterior pituitary)
HYPOTHALA
MUS
THALAMUS
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 33

34. CENTRAL NERVOUS SYSTEMBRAIN
Consists of fiber tracts
relaying information from
one region of brain to
another, origin of many
cranial nerves
Consists of two
hemispheres, responsible
for involuntary coordination
of skeletal muscle
contraction
CEREBELLU
M
PONS
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.72-78 34

35. CENTRAL NERVOUS SYSTEMBRAIN
Connects to spinal cord
Route impulses to higher
centres
Has region called RETICULAR
FORMATION
Contains three vital centers
 Cardiac center
 Vasomotor center
 Respiratory center
 Controls overall activity
of brain by enhancing or
inhibiting impulses
MEDULLA
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.72-78 35

36. CENTRAL NERVOUS SYSTEMBRAIN
VENTRICLES
OF BRAIN
LATERAL VENTRICLE:
In each cerebral hemsphere
THIRD VENTRICLE:
In diencephalon
FOURTH VENTRICLE:
In brain stem
Series of cavities that are connected to one
another and to central canal of spinal cord
Containing CSF
Sherwood L. Principles of neural and hormonal communication. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 36

37. CENTRAL NERVOUS SYSTEMBRAIN
NEUROTRANSMI
TTERS
Over 200 neurotransmitters are synthesized and
secreted by neurons in the brain
 ACETYLCHOLINE
 EPINEPHRINE/
NOREPINEPHRINE
 DOPAMINE
 GABA(GAMMA
AMINO BUTRYIC
ACID)
 ENKEPHALINS/
ENDORPHINS
Transmits impulses across synapses
Arouse brain & maintain alertness
Motor control
Motor coordination through inhibition
of certain neurons
Block transmission and perception of
pain
Van De Graaf KM, Rhees RW. Central nervous system. Schaum’s human anatomy and phisiology. McGraw hill; 2001 p.72-78 38

38. CENTRAL NERVOUS SYSTEM
SPINAL
CORD
 Continuous with brain & Extends
through the vertebral canal of
the vertebral column to level of
first lumbar vertebra
 Gives rise to 31 pairs of spinal
nerves
GREY MATER
(CENTRAL)
WHITE MATER
(PERIPHERAL)
INVOLVED IN
REFLEXES
ASCENDING &
DESCENDING
TRACTS INVOLVED
IN IMPULSE
CONDUCTION TO
& FROM BRAIN
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 39

39. CENTRAL NERVOUS SYSTEM
SPINAL
CORD
S
P
I
N
A
L
N
E
R
V
E
S
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 40

40. CENTRAL NERVOUS SYSTEM
SPINAL
CORD
SPINAL CORD
CROSS SECTION
REGIONS OF
GREY MATER
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 41

41. CENTRAL NERVOUS SYSTEM
SPINAL
CORD
SPINAL CORD
CROSS SECTION
REGIONS OF
WHITE MATER
LATERAL CORTICOSPINAL
RUBROSPINAL
VENTRAL CORTICOSPINAL
VESTIBULOSPINAL
DORSAL COLUMNS
DORSAL SPINOCEREBELLAR
VENTRAL SPINOCEREBELLAR
LATERAL SPINOTHALAMIC
VENTRAL SPINOTHALAMIC
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 42

42. CENTRAL NERVOUS SYSTEM
SPINAL
CORD
REFLEX
ARC
AFFERENT PATHWAY
EFFECTOR
INTERGRATING
PATHWAY
EFFERENT
PATHWAY
SENSORY RECEPTOR
 Neural pathway involved in accomplishing reflex
activity.
 5 components
AFFERENT PATHWAY
Sherwood L. The central nervous system. From cells to systems. 7th ed. Brooks Cole; 2010 p.87-132 43

43. PERIPHERAL NERVOUS
SYSTEM
CRANIAL NERVES
From inferior aspect of brain
AUTONOMIC
NERVOUS SYSTEM
SPINAL NERVES
From spinal cord
SOMATIC NERVOUS
SYSTEM
 PNS includes
 Consists of two functional divisions
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill;
2001 p.79-87
44

44. PERIPHERAL NERVOUS SYSTEM
ANS &
SOMATIC
AUTONOMIC
NERVOUS
SYSTEM
SOMATIC
NERVOUS
SYSTEM
CONSCIOUS / VOLUNTARY REGULATION
ALWAYS STIMULATORY
INVOLUNTRY REGULATION
FIBRES DO NOT SYNAPSE AFTER THEY
LEAVE THE CNS
FIBRES SYNAPSE AT A GANGLION
AFTER THEY LEAVE CNS
INNERVATES SKELETAL MUSCLE,FIBRESINNERVATES SMOOTH MUSCLE FIBRES,
CARDIAC MUSCLE AND GLANDS
EITHER STIMULATES OR INHIBITS
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill;
2001 p.79-87
45

45. PERIPHERAL NERVOUS SYSTEM
CRANIAL
NERVES
Innervate structures of head neck & trunk
Most mixed, some purely sensory, others
primarily motor
I OLFACTORY
II OPTIC
III OCCULOMOTOR
IV TROCHLEAR
V TRIGEMINAL XI ACCSESSORY
VII FACIAL
VIII VESTIBULOCOHLEAR
IX GLOSSOPHARYNGEAL
VI ABDUCENS
X VAGUS
XII HYPOGLOSSAL
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
46

46. PERIPHERAL NERVOUS SYSTEM
CRANIAL
NERVES
I OLFACTORY
III OCCULOMOTOR
IXGLOSSOPHARYNGEAL
SENSO
RY
CRANIAL NERVE PATHWAY FUNCTION
FROM OLFACTORY
EPITHELIUM
SMELL
FROM RETINA OF EYE SIGHT
FROM ORGANS OF
HEARING & BALANCE
HEARING, BALANCE &
POSTURE
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
47

47. PERIPHERAL NERVOUS SYSTEM
CRANIAL
NERVES
III OCCULOMOTOR
IV TROCHLEAR
VI ABDUCENS
PRIMARILY MOTOR (
ALSO PROPRIOCEPTIVE)
CRANIAL NERVE PATHWAY FUNCTION
FOUR EYE MUSCLES CILIARY
BODY
MOVEMENT OF EYE &
EYELID FOCUSSING CHANGE
IN PUPIL SIZE
TO SUPERIOR OBLIQUE MOVEMENT OF EYE
TO LATERAL RECTUS
MUSCLE
MOVEMENT OF EYE
XI ACCSESSORY
XII HYPOGLOSSAL
TO TRAPEZIUS
STERNOCLEIDOMASTOID
HEAD + SHOULDER MOVNT
MUSCLE SENSE
TO MUSCLES OF TONGUE SPEECH, SWALLOWING
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
48

48. PERIPHERAL NERVOUS SYSTEM
CRANIAL
NERVES
V
TRIGEMIN
AL
V1 OPHTHALMIC
V2 MAXILLARY
MIXED-(SENSORY+
MOTOR)
CRANIAL NERVE PATHWAY FUNCTION
Sensory from skin of
cornea, upper 1/3rd of face,
nasal mucosa
General sensation from
skin of face
Sensory from middle 1/3rd
of face, teeth+gums of upper
jaw lateral & inferior nasal
mucosa
General sensation from
skin of face
V3 MANDIBULAR Sensory from lower 1/3rd of
face, teeth & gums of lower
jaw, mucosa of mouth,
anterior 2/3rd of tongue
Motor to muscles of
mastication
Chewing of food
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
49

49. PERIPHERAL NERVOUS SYSTEM
CRANIAL
NERVES
VII FACIAL
IXGLOSSOPHARYNGEAL
X VAGUS
MIXED-(SENSORY+
MOTOR
CRANIAL NERVE PATHWAY FUNCTION
SENSORY from taste buds
MOTOR to facial muscles
salivary &lacrimal glands
Taste, movement of face,
secretion of saliva & tears
SENSORY from pharyngeal
muscles & taste buds
MOTOR to pharyngeal
muscles & salivary glands
Taste, swallowing,
secretion of saliva
SENSORY from viscera,
taste buds
MOTOR to viscera
Visceral sensations,
taste, visceral muscles
and glands
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
50

50. PERIPHERAL NERVOUS SYSTEM
SPINAL
NERVES
 Each spinal nerve is a mixed nerve
 Attached to spinal cord by a posterior
/dorsal root of sensory nerves
Anterior or ventral root of motor
fibers
 A ganglion located on posterior root
called dorsal root ganglion contains
cell bodies of sensory neurons
8 CERVICAL
12 THORACIC
5 LUMBAR 31 PAIRS
5 SCARAL
1 COCCIGEAL
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
51

51. PERIPHERAL NERVOUS
SYSTEM
PROPRIOCEPTORS
EXTRORECEPTORS
INTERORECEPTORS
Distal terminals of sensory nerves that respond to physical
stimuli & convert them into nervous impulses for conduction
towards CNS
STIMULATED BY IMMEDIATE
EXTERNAL ENVIRONMENT
LOCATED IN & TRANSMIT
IMPULSES FROM CAVITIES
OF BODY
GIVE INFO ABOUT
PRESENCE, POSITION &
MOVEMENT OF BODY
SENSORY
RECEPTORS
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
52

52. PERIPHERAL NERVOUS
SYSTEM
KRAUSE’S CORPUSCLES –
Cold recptors
FREE NERVE ENDINGS –
Superficial pain & touch MERKEL’S CORPUSCLES -
Tactile receptors in submucosa
of tongue & oral mucosa
MEISSNER’S CORPUSCLES -
Tactile receptors in skin
RUFFINI’S CORPUSCLES –
Pressure & warmth receptors
SENSORY
RECEPTORS
EXTRORECE
PTORS
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
53

53. PERIPHERAL NERVOUS
SYSTEM
PACINIAN CORPUSCLES –
Perception of pressure
FREE NERVE ENDINGS –
Visceral pain & other
sensations
SENSORY
RECEPTORS
INTROCEPT
ORS
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
54

54. PERIPHERAL NERVOUS
SYSTEM
GOLGI TENDON ORGANS –
Mechanoreceptors in
tendons of muscles
MUSCLE SPINDLE –
Mechanoreceptors between
skeletal muscle fibres
PERIODONTAL
MECHANORECEPTORS –
Responds to biomechanical
stimuli
PACCINIAN CORPUSCLES –
Perception of pressure
FREE NERVE ENDINGS – Deep
somatic pain & other
sensations
SENSORY
RECEPTORS
PROPRIOCE
PTORS
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
55

55. PERIPHERAL NERVOUS SYSTEM
AUTONOMIC
NERVOUS SYTEM
SYMPATH
ETIC
RESPONSE
ACTIONS
FLIGHT & FRIGHT
 HEART RATE
 STRENGTH OF
CONTRACTION
 BLOOD PRESSURE
 BLOOD GLUCOSE
DIGESTIVE ACTIVITY
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
56

56. PERIPHERAL NERVOUS SYSTEM
AUTONOMIC
NERVOUS SYTEM
PARASYMPAT
HETIC
RESPONSE
ACTIONS
REST & DIGEST
 HEART RATE
 BLOOD GLUCOSE
 DIGESTIVE ACTIVITY
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
57

57. PERIPHERAL NERVOUS SYSTEM
AUTONOMIC
NERVOUS SYTEM
SYMPATH
ETIC
PARASYMPA
THETIC
FEATU
RES
ORIGIN OF
PREGANGLIONIC
FIBRES
THORACOLUMBAR
NERVES
CRANIOSACRAL NERVES
LOCATION OF
GANGLIA
FAR FROM VISCERAL
EFFECTOR ORGANS IN
SYMPATHETIC CHAIN
NEAR OR WITHIN VISCERA
EFFECTOR ORGANS
NEUROTRANSMITT
OR
IN GANGLIA
ACETYLCHOLINE, IN
EFFECTOR ORGANS
NOREPINEPHRINE
IN GANGLIA ACETYLCHOLINE,
IN EFFECTOR ORGANS
ACETYLCHOLINE
Van De Graaf KM, Rhees RW. Peripheral and autonomic nervous system. Schaum’s human anatomy and physiology. McGraw hill; 2001 p.79-87
58

58. MECHANISM OF PAIN
"Pain is an unpleasant sensory and emotional
experience associated with actual or potential
tissue damage, or described in terms of such
damage” - IASP
INTRODUC
TION
DEFINITIO
N
PROTECTIVE MECHANISM – Manifested when environmental
change occurs that cause injury to responsive tissue
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 59

59. MECHANISM OF PAIN
INTRODUC
TION
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43
60
P
N
S
SPINAL
CORD
BRAIN
THERMAL
MECHANICAL
CHEMICAL
NOXIUOS STIMULI
SENSORY
RECEPTOR
PRIMARY
AFFERENT/ 1ST
ORDER NEURON
SECOND ORDER
NEURON
ANTEROLATERAL
SPINOTHALAMIC
TRACT
HIGHER CENTRES
A DELTA
C FIBRES
NOCICEPTIVE SPECIFIC NEURON
WIDE DYNAMIC RANGE NEURON
NEOSPINOTHALAMIC TRACT- CARRY A DELTA
PALEOSPINOTHALAMIC TRACT – CARRY C FIBRE
MEDULLA, THALAMUS,
CEREBRAL CORTEX

60. MECHANISM OF PAIN
SENSATION OF PAIN – 3 components
 MOTIVATED BEHAVIORAL RESPONSES - withdrawal/
defense
 EMOTIONAL REACTIONS - crying/fear
 SUBJECTIVE PERCEPTION - influenced by past/present
experiences
INTRODUC
TION
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43 61

61. MECHANISM OF PAIN
INTRODUC
TION
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
62
TRANSDUCTION
TRANSMISSION
PERCEPTION
MODULATION
FUNCTIONAL PROCESS
OF PAIN

62. MECHANISM OF PAIN
INTRODUC
TION
Firelight media group.Phases of nociceptive pain. http://www.youtube.com/watch?v=PMZdkac4YLk. Vowhow pictures. January 2013.
63

63. MECHANISM OF PAIN
INTRODU
CTION
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 64
THALAMUS
FIRST ORDER NEURON
SOMATOSENSORY CORTEX
THIRD ORDER NEURON
SECOND ORDER NEURON
SPINAL CORD
MEDULLA
NOCICEPTOR
LATERALSPINOTHALAMIC TRACT
ANTEROLATERAL QUADRANT

64. MECHANISM OF PAIN
THEORI
ES
SPECIFICITY THEORY
PATTERN THEORY
GATE CONTROL
THEORY
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 65

65. MECHANISM OF PAIN
THEORI
ES
SPECIFICITY
THEORY
DESCARTES (1644)
• Concept of pain system - straight through
channel from the skin to the brain
VON FREY
 concept of specific cutaneous receptors for the
mediation of touch, heat, cold & pain.
 Free nerve endings implicated as pain receptors
 A pain centre thought to exist in brain
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 66

66. MECHANISM OF PAIN
THEORI
ES
PATTERN
THEORY
GOLDSCHEIDER (1894)
• Proposed concepts of stimulus intensity & central
summation
• Patterns of nerve impulses that evoke pain
produced by summation of sensory input
• Pain results when total output of the cells
exceeds a critical level
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 67

67. MECHANISM OF PAIN
THEORI
ES
GATE CONTROL
THEORY
MELZACK & WALL (1965)
• Injury info transmitted by SMALL PERIPHERAL NERVES
• Cells in SC or nucleus of fifth cranial nerve excited by
signals also facilitated/inhibited by LARGE PERIPHERAL
NERVES carrying info about non noxious events
• Descending control systems originating in brain
modulate the excitability of cells transmitting
information
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44 68

68. MECHANISM OF PAINGATE CONTROL
THEORY
Nachum Dafny.Pain Modulation and Mechanisms.http://nba.uth.tmc.edu/neuroscience/s2/chapter08.html. Neuroscience online.
UTH.University of Texas.January 2013.
69

69. MECHANISM OF PAIN
GATE CONTROL
THEORY
TRANSMISSION
NERVE CELLS
GATE
UNMYELINATED PAIN
NERVES ACTIVITY
OPENS THE GATE
LARGE MYELINATED
ACTIVITY ACTIVITY
CLOSES THE GATE
MESSAGES FROM
BRAIN
MESSAGES TO
BRAIN
70

70. MECHANISM OF PAIN
Grey mater of spinal cord
organised into 10 laminae - LAMINAE OF REXED
 Layer II in dorsal horn called SUBSTANTIA GELATINOSA
 Substantia gelatinosa contain small neurons with short
processes
GATE CONTROL
THEORY
ANATOMY OF GATE
CONTROL SYSTEM
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
71

71. MECHANISM OF PAIN
GATE CONTROL
THEORY
ANATOMY OF GATE
CONTROL SYSTEM
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
72
Substantia
gelatinosa
Transmission
cells
Adjacent to SG – cell bodies of neurons called TRANSMISSION CELLS / T cells
dendrites of T cells
synapse with SG cell
bodies
axons of T cells send branches to
lateral area of white mater in
contralateral area of spinal cord
Axons of T cells joined by other T cell axons from
different level of spinal cord – LATERAL SPINOTHALAMIC
TRACT – Pathway for pain & temperature
Tract carry info to
higher centres in
brain

72. MECHANISM OF PAIN
Large diameter fibers excite SG cells - send inhibitory impulses to T
cells
GATE IS CLOSED
Impulses from A delta & C fibers inhibit SG cells, preventing SG cells
from sending inhibitory impulses to T cells
OPENS THE GATE
GATE CONTROL
THEORY
WORKING OF GATE
CONTROL SYSTEM
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
73

73. THALAMUS
BRAIN
TRANSMISSION
CELLS
SUBSTANTIA
GELATINOSA
Gate control cells
ACTIONSYSTEM(BEHAVIOURAL,MUSCULAR,VISCERAL
E
E I
I E
I
LARGE
DIAMETER
FIBERS
SMALL
DIAMETER
FIBERS
(GREY MATER) DORSAL HORN OF SPINAL
CORD
PAINLATERALSPINOTHALAMIC
TRACT
CORTICOSPINAL TRACT
ASCENDING COLLATERAL
COLLATERAL
COLLATERAL
GATE CONTROL
THEORY
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
74

74. MECHANISM OF PAIN
three categories of pain receptors, or nociceptors:
PAIN
RECEPTORS
CATEGORIES
POLYMODAL
NOCICEPTORS
THERMAL
NOCICEPTORS
MECHANICAL
NOCICEPTORS
Respond to mechanical damage -
cutting, crushing, or pinching
respond to temperature extremes,
especially heat;
Respond to all kinds of damaging stimuli,
including irritating chemicals released
from injured tissues
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
75

75. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
SIGNAL FROM
POLYMODAL
NOCICEPTORS
SIGNALS FROM
MECHANICAL &
THERMAL
NOCICEPTERS
VIA A DELTA
FIBRES
FAST PAIN
PATHWAY
5TH
CRANIAL
NERVE
VIA C FIBRES
SLOW PAIN
PATHWAY
OROFACIAL
REGION
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
76
PONS
( trigeminal
spinal
nucleus)

76. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
OROFACIAL
REGION
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
77
TRIGEMINOSPINAL TRACT
– THALAMUS
THALAMUS –
THALAMOCORTICAL
TRACT - CORTEX

77. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
ACTIVATION OF A
DELTA & C FIBRES
SIGNALS VIA 5TH 7TH,9TH , 10TH CRANIAL NERVES, 1ST,2ND ,3RD
SPINAL NERVES & VISCERAL AFFERENTS THROUGH CERVICAL
SYMPATHETIC CHAIN
TO TRIGEMINAL
NUCLEAR
COMPLEX
RETICULAR
FORMATION
SOLITARY TRACT
NUCLEUS
CERVICAL DORSAL
SPINAL CORD
OROFACIAL
REGION
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
Quintessence; 2002 p.181-201
78

78. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
TRIGEMINAL
NUCLEAR
COMPLEX
OROFACIAL
REGION
NUCLEUS ORALIS
NUCLEUS
INTERPOLARIS
NUCLEUS CAUDALIS/
MEDULLARY DORSAL
HORN
INCLUDES
 Pain fibers from maxillofacial area terminate in nucleus caudalis
 Initial synapses occur in nucleus caudalis where SECONDARY MEDULLARY/
SECOND ORDER TRIGEMINAL NEURONS BEGIN
MAIN SENSORY
TRIGEMINAL
NUCLEUS
SPINAL
TRACT OF
TRIGEMINAL
NUCLEUS
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
79

79. MECHANISM OF PAIN
SUBNUCLEUS
CAUDALIS
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
 SUBNUCLEUS CAUDALIS HOMOLOGOUS TO
SUBSTANTIA GELATINOSA OF SPINAL DORSAL HORN
 subnucleus caudalis predominates in trigeminal
nociception
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
80

80. MECHANISM OF PAIN
SUBNUCLEUS
CAUDALIS
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
 Nucleus caudalis termed MEDULLARY DORSAL HORN –
anatomical organisation similar to spinal dorsal horn
RELAY STATION NOCICEPTIVE
SIGNALS ARE TRANSFERRED TO
HIGHER BRAIN REGIONS
PROCESSES & MODULATES
NOCICEPTIVE SIGNALS
INCREASED - HYPERALGESIA
DECREASED ANALGESIA
MISINTERPRETED -
REFFERED PAIN
OUTPUT TO
HIGHER BRAIN
CENTERS
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
Quintessence; 2002 p.181-201
81

81. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
OROFACIAL
REGION
PRIMARY NOCICEPTIVE AFFERENTS
A DELTA & C FIBERS
RELEASE OF EXCITATORY NEUROTRANSMITTER
GLUTAMATE FROM NERVE TERMINALS
BINDING WITH NMDA
RECEPTORS
GLUTAMATE ACT ON 2 DIFFERENT PLASMA MEMBRANE RECEPTORS
BINDING WITH AMPA
RECEPTORS
VIA TRIGEMINAL TRACT ENTER
MEDULLARY DORSAL HORN
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
82

82. MECHANISM OF PAIN
TRANSMISSION OF NOCICEPTIVE
INFORMATION TO CNS
OROFACIAL
REGION
BINDING WITH NMDA
RECEPTORS
BINDING WITH AMPA
RECEPTORS
PERMEABILITY CHANGES IN
NERVE MEMBRANE
CALCIUM ENTRY INTO
NEURONS
Ca IONS INITIATE SECOND
MESSENGER SYSTEMS
MAKES DORSAL HORN CELL
MORE EXCITABLE
EXAGGERATED SENSITIVITY
OF INJURED AREA
GENERATION OF ACTION
POTETIAL IN DORSAL HORN CELLS
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
83

83. MECHANISM OF PAIN
PROJECTION TO
THALAMUS
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
SYNAPTIC
JUNCTIONS IN
SUBNUCLEUS
CAUDALIS
PRIMARY
AFFERENT
NEURONS
SECOND
ORDER
TRGEMINAL
NEURONS
PROJECTION INTO THALAMUS
SECOND ORDER
NEURONS 3 TYPES
WIDE DYNAMIC RANGE
NEURONS (WDR)
NOCICEPTIVE- SPECIFIC
NEURONS (NS)
LOW THRESHOLD
MECHANORECEPTOR
AFFERENTS (LTM)
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
Quintessence; 2002 p.181-201
84

84. MECHANISM OF PAIN
PROJECTION TO
THALAMUS
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
WIDE DYNAMIC RANGE
NEURONS (WDR)
NOCICEPTIVE- SPECIFIC
NEURONS (NS)
LOW THRESHOLD
MECHANORECEPTOR
AFFERENTS (LTM)
Wide range of stimuli- nonnoxious
& noxious
Input from thin nociceptive fibres
activated by intense noxious
mechanical & thermal stimuli
Nonnociieptive & respond to light
tactile stimuli, pressure &
proprioception
RESPOND TO
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
Quintessence; 2002 p.181-201
85

85. MECHANISM OF PAIN
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
 Ascending pain pathways have different destinations in
CORTEX, THALAMUS, AND RETICULAR FORMATION.
 Interconnections from the thalamus and reticular formation to
hypothalamus and limbic system - behavioral & emotional
responses to pain
 limbic system - perceive the unpleasant aspects of pain
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
86

86. MECHANISM OF PAIN
TRANSMISSION OF
NOCICEPTIVE
INFORMATION TO CNS
 Cortical somatosensory processing areas -localize the pain
 other cortical areas - pain experience, deliberation about the
incident
 The reticular formation - increases the level of alertness
associated with the noxious encounter
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
87

87. MECHANISM OF PAIN
DESCENDING
IHIBITORY SYSTEM
 Represents a specific intrinsic analgesic mechanism
 descending pathway send chemical substances /nerve
impulses back down to the cells of spinal cord
 Several structures involved inhibitory mechanism
PERIAQUADUCTAL GREY
MATTER (PAG)
PERIVENTRICULAR
STRUCTURES
MEDULLARY RAPHE
NUCLEI
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
88

88. MECHANISM OF PAIN
ENDOGENOUS
ANTINOCICEPTIVE SYSTEM
 Endorphins modulate & decrease pain
 Several types of endorphins
METHIONINE
ENKEPHALINS
LEUCINE ENKEPHALINS
ALPHA ENDORPHIN
BETA ENDORPHIN
GAMMA ENDORPHIN
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
89
DYNORPHIN
DELTA
KAPPA
MU

89. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
 Chemical agents play important role in neural mechanism of
pain
ALOGENIC AGENTS
NEUROTRANSMITTORS
NEUROMODULATORS
Produces pain
S stored in neuron for release during
neural activity,
Interact with post synaptic receptors
no obsevable action on the target
cells, modify release of
neurotransmittors from pre synaptic
terminal
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
90

90. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
Several types of chemical agents
INHIBITORY AGENTS
EXCITATORY AGENTS
INFLAMMATORY AGENTS
Serotonin
GABA
Endorphins
Glycine
Somatostatin
dopamine
Acetyl choline
Norepinephrine
Glutamate
Substance p
Histamine
Prostaglandins
bradykinin
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
91

91. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
PROSTAGL
ANDINS
 Group of long chain hydroxy fatty acids
 Occurs in conjunction with inflammatory process
Cell membrane (phospholipids)
Arachidonic acid
Cyclic endoperoxides
PROSTACYCLIN PGI 2 PGE2 PGF2
SENSITIZE NOCICEPTIVE NERVE ENDINGS, LOWERING PAIN THRESHOLD
PHOSPHOLIPASE A 2
CYCLOXYGENASE
PROSTACYCLIN
SYNTHETASE PROSTAGLANDIN SYNTHETASE
FORMATION OF
PROSTAGLANDINS
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
92

92. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
BRADYKINI
N
 Endogenous polypeptide – excites all receptors
 Occurs in conjunction with inflammatory process
 Vasodilator & increase capillary permeability
BRADYKININ PROSTAGLANDIN
Require for action
Stimulates release of
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
93

93. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
SEROTONIN
 Monoamine released by blood platelets
 Synthesised in CNS from tryptophan
 Released when nucleus raphae magnus, PAG is stimulated by
sensory input
 In CNS element of antinociceptive mechanism
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
94

94. MECHANISM OF PAIN
BIOCHEMICAL BASIS OF
NOCICEPTION
SUBSTANC
E P
 Polypeptide released in terminals of primary nociceptive
neurons
 In CNS Acts as excitatory neurotransmitter for nociceptive
impulses
Richard BC. Pain. Pain. Monheim’s local anaesthesia and pain control in dental practice. 7th ed. Missouri: Mosby; 2001 p.1-44
95

95. MECHANISM OF PAIN
Byers MR, Narhi MVO. Nerve supply of the pulpodentin complex and resonses to injury. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and
96
SENSITIZATION
PERIPHERAL CENTRALL
• Concentration of
inflammatory mediators
• Tissue pressure
• Changes in afferent fibre –
SPROUTING
• Barrage of impulses from
nociceptors
LOWERING OF THRESHOLD TO NOXIOUS STIMULI

96. MECHANISM OF DENTAL PAIN
INFLAMMATORY
MEDIATORS
SENSITIZE OR
DEPOLARIZE
NOCICEPTORS
ACTIVATION OF
C FIBERS
INNERVATING
PULPAL TISSUE
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
97

97. MECHANISM OF DENTAL PAIN
NOXIUOS PHYSICAL
STIMULI
EFFECTS DENTINAL
FLUID FLOW
ACTIVATION OF
A DELTA
FIBERS
INNERVATING
DENTINAL
TUBULES
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
98

98. MECHANISM OF DENTAL PAIN
INFLAMMATI
ON
INFLAMMED DENTAL PULP WITH
INFLAMMATORY MEDIATORS
DETECTION OF INFL MEDIATORS BY
RECEPTORS ON TERMINALS OF
NOCICEPTIVE PRIMARY AFFERENTS
ACTIVATION OF RECEPTOR &
SUBSEQUENT DEPOLARIZATION
OF NERVE MEMBRANE
CONDUCTION OF SIGNAL TO CNS
SENSITIZATION OF NOCICEPTOR
 Spontaneous depolarization
 Reduced threshold for stimulation
 Increased after discharges to
suprathreshold stimuli
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
99

99. MECHANISM OF DENTAL PAIN
ALTERED PAIN
STATES
ALLODYNI
A
 Reduction in pain threshold so that previously non
noxious stimuli are perceived as painful
 Percussion test, Palpation test
HYPERAL
GESIA
 Increase in perceived magnitude of a painful stimulus
 Increased response to electric pulp tests
Okeson JP. The neural anatomy of orofacial pain. Bell’s orofacial pains. 5th ed. USA: Quintessence;1995. p 13-43.
100

100. Pain perceived to be localized in one region but caused by
nociception originating in another area
Site of pain different from source of pain
ALTERED PAIN
STATESREFERRED
PAIN
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental Pulp. China:
Quintessence; 2002 p.181-201 101

101. INFLAMMED
MANDIBULAR MOLAR
MAXILLARY MOLAR
SUP/INF BELLY OF
MASSETER
MAX/MAND
POSTERIOR TEETH
ALTERED PAIN
STATES
Hargreaves KM. Pain mechanisms of pulpodentin complex. In:Hargreaves KM, Seltzer S, Goodis HE . Seltzer and Bender's Dental
Pulp. China: Quintessence; 2002 p.181-201 102
REFERRED
PAIN

102. DENTIN INNERVATION
THEORY
DENTINAL
HYPERSENSITIVITY
DENTINOBLASTIC
INJURY
Nerve fibers within dentinal tubules when injured, initiate nerve
impulse
Dentinoblast injury produce stimuli received by free nerve endings
within tubules or in contact with any part of dentinoblast
Stimulus - chemicals released by injured cells
- changes in electric potential
HYDRODYNAMIC
THEORY
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104 103

103. HYDRODYNAMIC
THEORY
Dentinal tubules
WELL INNERVATED NEAR PULP HORNS
FEW INNERVATIONS IN MID CROWN LEVEL
POOR INNERVATION IN ROOT DENTIN
Innervations in close proximity to odontoblasts
Sharp quality of pain suggest activation of A delta fibers
Movement of
fluid through
dentinal tubules
Stimulate
nociceptive
fibers
Result in pain
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104 104
DENTINAL
HYPERSENSITIVITY

104. HYDRODYNAMIC
THEORY Pain asosciated with stimulation due to movement of fluid within the
tubule
COLD
HEAT
EXPANSION OF TUBULE
FLUID
INWARD FLOW
TOWARDS PULP
OUTWARD FLOW
CONTRACTION OF
TUBULE FLUID
AIR
BLASTS,ABSO
RBENT
MATERIALS,
AND SUGAR
EVAPORATION OF
FLUID/CHANGE
OSMOTIC GRADIENT
FLUID MOVEMENT
FROM DEEPER AREAS
Weine FS. Diseases of pulp and periapex. In: Weine FS. Endodontic therapy. 3rd ed. Missouri: Mosby; 1982. p.90-104
105
DENTINAL
HYPERSENSITIVITY

105. 106
DUAL NATURE OF
PAIN
PAIN PERCEPTION –
PHYSIO ANATOMICAL
PROCESS
PAIN REACTION –
PYCHOPHYSIOLOGICAL
PROCESS
IS FAIRLY CONSTANT IN HEALTHY
INDIVIDUALS
VARIES MARKEDLY FROM ONE
INDIVIDUAL TO ANOTHER
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