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Anatomy of AcupunctureAnatomy of Acupuncture
Important Pathways for Pain Important Pathways for Pain Control & Acupuncture ReliefControl & Acupuncture Relief
Spinal CordSpinal CordA. Spinal cord anatomyA. Spinal cord anatomy
1. Protection and coverings1. Protection and coverings a. Vertebral columna. Vertebral column b. Meningesb. Meninges 2. External anatomy of the spinal cord2. External anatomy of the spinal cord 3. Internal anatomy of the spinal cord3. Internal anatomy of the spinal cord
B. Spinal cord physiologyB. Spinal cord physiology 1. Reflexes1. Reflexes 2. Reflex arc and homeostasis2. Reflex arc and homeostasis a. Physiology of the stretch reflexa. Physiology of the stretch reflex b. Physiology of the flexor (withdrawal)b. Physiology of the flexor (withdrawal) reflex and crossed extensor reflexesreflex and crossed extensor reflexes
C. Spinal nervesC. Spinal nerves 1. Composition and coverings1. Composition and coverings 2. Distribution of spinal nerves2. Distribution of spinal nerves 3. Dermatomes3. Dermatomes
The Spinal CordThe Spinal Cord1. is continuous with brain1. is continuous with brain
2. mediates spinal reflexes2. mediates spinal reflexes
3. is site for integration3. is site for integration
4. provides the pathways4. provides the pathways
Protection and CoveringsProtection and Coverings1. vertebral canal1. vertebral canal
2. meninges2. meninges
3. cerebrospinal fluid3. cerebrospinal fluid
Meninges and SpacesMeninges and Spaces
1. epidural space1. epidural space
2. dura mater2. dura mater
3. subdural space3. subdural space
4. arachnoid membrane4. arachnoid membrane
5. subarachnoid space5. subarachnoid space
6. pia mater6. pia mater
-- denticulate ligaments-- denticulate ligaments
External AnatomyExternal Anatomy
1. cylindrical1. cylindrical2. flattened A-P2. flattened A-P3. foramen magnum to L23. foramen magnum to L24. differential growth4. differential growth5. cervical enlargement5. cervical enlargement6. lumbar enlargement6. lumbar enlargement7. conus medullaris7. conus medullaris8. filum terminale8. filum terminale9. cauda equina9. cauda equina10. functional segments10. functional segments
Internal AnatomyInternal Anatomy
1. gray matter1. gray matter
2. white matter2. white matter
3. gray commissure3. gray commissure
4. central canal4. central canal
1. gray matter1. gray matter
2. white matter2. white matter
3. gray commissure3. gray commissure
4. central canal4. central canal
Gray MatterGray Matter
1. nuclei1. nuclei
2. horns2. horns
a. dorsal -- sensorya. dorsal -- sensory
b. ventral -- motorb. ventral -- motor
c. lateral -- autonomicc. lateral -- autonomic
Spinal Cord Grey MatterSpinal Cord Grey Matter
Spinal LayersSpinal Layers◦ Spinal grey matters Spinal grey matters
divided into 10 layersdivided into 10 layers
Substantia GelatinosaSubstantia Gelatinosa◦ Composed of a layer of cell Composed of a layer of cell
bodies running up and down bodies running up and down the dorsal horns of the spinal the dorsal horns of the spinal cordcord
◦ Receive input from A and C-Receive input from A and C-fibersfibers
◦ Activity in SG inhibits pain Activity in SG inhibits pain transmissiontransmission
Spinal Nerve RootsSpinal Nerve Roots1. dorsal root (axons of sensory neurons)1. dorsal root (axons of sensory neurons)
-- dorsal root ganglion (cell bodies of sensory -- dorsal root ganglion (cell bodies of sensory neurons)neurons)
2. ventral root (axons of motor neurons)2. ventral root (axons of motor neurons)
Dorsal root ganglion
Dorsal roots
Ventral roots
White MatterWhite Matter
1. columns1. columns
a. anteriora. anterior
b. posteriorb. posterior
c. lateralc. lateral
2. tracts2. tracts
a. ascendinga. ascending
b. descendingb. descending
Posterior columns
Anterior columns
Lateral columns
Lateral columns
Tracts of the Spinal CordTracts of the Spinal Cord
The Spinal Cord Has Two Essential The Spinal Cord Has Two Essential FunctionsFunctions
1. convey impulses between the periphery 1. convey impulses between the periphery and the brainand the brain
2. provide integrating centers for spinal 2. provide integrating centers for spinal reflexesreflexes
Reflexes are…Reflexes are…
1. inborn1. inborn
2. unlearned2. unlearned
3. unconscious3. unconscious
Somatic Reflexes Versus Visceral Somatic Reflexes Versus Visceral ReflexesReflexes
Somatic reflexes involve the somatic Somatic reflexes involve the somatic nervous system.nervous system.
Visceral reflexes involve the autonomic Visceral reflexes involve the autonomic nervous system.nervous system.
Reflex ArcReflex Arc
1. receptor1. receptor
2. sensory neuron2. sensory neuron
3. integration center3. integration center
4. motor neuron4. motor neuron
5. effector5. effector
sensory receptor
1
2
3
4
5
sensory (afferent) neuron
center of integration with association neuron
motor (efferent) neuron
effector
sensory receptor
2
3
4
5
sensory (afferent) neuron
center of integration with association neuron
motor (efferent) neuron
effector
THE REFLEX ARC AS A FEEDBACK SYSTEM
CONTROLLED CONDITION
A stimulus or stress disrupts membrane homeostasis by altering some controlled
condition
RECEPTORThe receptors in a reflex are sensory
neurons associated with a receptor device (transducer) and which relay nerve impulses to a central control center
CONTROL CENTERThe control center is an integrating center
of neurons in the CNS. It relays the information to motor neurons
EFFECTORSThe motor neurons initiate some response
by an effector (muscle or gland) to counteract the stimulus that originally
disrupted homeostasis
RETURN TO HOMEOSTASISThe action of the effector returns the
body process to within its normal homeostatic range
Stretch ReflexStretch Reflex
1. monosynaptic1. monosynaptic
2. muscle spindle2. muscle spindle
3. muscle tone3. muscle tone
4. ipsilateral4. ipsilateral
5. reciprocal innervation5. reciprocal innervation
The Flexor and Crossed Extensor ReflexThe Flexor and Crossed Extensor Reflex
IntersegmentalPolysynapticContralateral Pain receptorRole of association neuronsReciprocal innervationexcitatory neurons
inhibitory neurons
IntersegmentalPolysynapticIpsilateral Pain receptorRole of association neuronsReciprocal innervation
The Nervous System and Pain The Nervous System and Pain
Pain Pathways – Going UpPain Pathways – Going Up
Pain information travels Pain information travels up the spinal cord through up the spinal cord through the spinothalamic track (2 the spinothalamic track (2 parts)parts)– PSTT PSTT
Immediate warning of Immediate warning of the presence, location, the presence, location, and intensity of an and intensity of an injuryinjury
– NSTTNSTTSlow, aching reminder Slow, aching reminder that tissue damage has that tissue damage has occurredoccurred
Pain Pathways – Going DownPain Pathways – Going Down
Descending pain Descending pain pathway pathway responsible for pain responsible for pain inhibitioninhibition
The Neurochemicals of Pain The Neurochemicals of Pain
Pain InitiatorsPain Initiators◦Glutamate - CentralGlutamate - Central◦Substance P - CentralSubstance P - Central◦Brandykinin - PeripheralBrandykinin - Peripheral◦Prostaglandins - PeripheralProstaglandins - Peripheral
Pain InhibitorsPain Inhibitors◦SerotoninSerotonin◦EndorphinsEndorphins◦EnkephalinsEnkephalins◦DynorphinDynorphin
Theories of Pain Theories of Pain
Specificity TheorySpecificity Theory– Began with AristotleBegan with Aristotle– Pain is hardwiredPain is hardwired
Specific “pain” fibers bring info to a “pain center”Specific “pain” fibers bring info to a “pain center”
– Refuted in 1965Refuted in 1965
Gate Control TheoryGate Control Theory
Gate-Control Theory – Gate-Control Theory – Ronald Melzack (1960s)Ronald Melzack (1960s)
Described physiological mechanism by Described physiological mechanism by which psychological factors can affect the which psychological factors can affect the experience of pain.experience of pain.
Neural gate can open and close thereby Neural gate can open and close thereby modulating pain.modulating pain.
Gate is located in the spinal cord.Gate is located in the spinal cord.– It is the SGIt is the SG
Opening and Closing the GateOpening and Closing the Gate
When the gate is closed signals from small When the gate is closed signals from small diameter pain fibres do not excite the diameter pain fibres do not excite the dorsal horn transmission neurons.dorsal horn transmission neurons.
When the gate is open pain signals excite When the gate is open pain signals excite dorsal horn transmission cellsdorsal horn transmission cells
Three Factors Involved in Opening Three Factors Involved in Opening and Closing the Gateand Closing the Gate
The amount of activity in the pain fibers.The amount of activity in the pain fibers.
The amount of activity in other peripheral The amount of activity in other peripheral fibers.fibers.
Messages that descend from the brain.Messages that descend from the brain.
Conditions that Open the GateConditions that Open the Gate
Physical conditionsPhysical conditions– Extent of injuryExtent of injury– Inappropriate activity levelInappropriate activity level
Emotional conditionsEmotional conditions– Anxiety or worryAnxiety or worry– TensionTension– DepressionDepression
Mental ConditionsMental Conditions– Focusing on painFocusing on pain– BoredomBoredom
Conditions That Close the GateConditions That Close the Gate
Physical conditionsPhysical conditions– MedicationsMedications
– Counter stimulation (e.g., heat, massage)Counter stimulation (e.g., heat, massage)
Emotional conditionsEmotional conditions– Positive emotionsPositive emotions
– Relaxation, RestRelaxation, Rest
Mental conditionsMental conditions– Intense concentration or distractionIntense concentration or distraction
– Involvement and interest in life activitiesInvolvement and interest in life activities
Mechanisms that Regulate APMechanisms that Regulate AP
Inhibitor of APInhibitor of AP– CholecytokininCholecytokinin
Enhancer of APEnhancer of AP– L-phenylalanineL-phenylalanine
ConclusionConclusion
Knowledge of the functional anatomy of Knowledge of the functional anatomy of the nervous system may be useful in the nervous system may be useful in determining how acupuncture works since determining how acupuncture works since all evidence suggests that the effects all evidence suggests that the effects acupuncture can be explained only by its acupuncture can be explained only by its affects on the nervous system.affects on the nervous system.