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Flashcards in Neuro - Week 1 Deck (176):
1

What types of Stimulus do general sensory receptors encode? (4)

1) Quality: brush, pressure, vibration, temperature, pain
2) Intensity: light stroke vs. intense pressure
3) Duration:
4) Location:

2

What is a Receptive Field?

Area in periphery (ex. skin) where an adequate stimulus causes a response in a neuron.

3

How does a sensory neuron encode intensity? (2)

Rate Code: Frequency of AP's firing per neuron. The more action potentials firing, the higher the intensity

Spatial Summation Code: Number of neurons firing. The more neurons firing, the higher the intensity

4

What factors influence conduction velocity? (2)

1) AXON DIAMETER (higher = faster)

2) MYELINATION (thicker = faster)

5

Which fibers have the LARGEST myelin and FASTEST conduction? (2)

1) A alpha fibers: muscle spindle
2) A beta fibers: light touch, vibration, pressure

6

Which fibers have THIN myelin and MEDIUM conduction? (1)

A delta fibers: Nociceptors (fast pain), cooling receptors

7

Which fibers are UNMYELINAED and have the SLOWEST conduction? (1)

Nociceptors (slow pain) and warm receptors

8

What is a Remap Bundle?

a bundle of Nociceptors

9

What would a Compound AP from a nerve look like if there was a loss of access to a particular nerve fiber?

The magnitude of the peak corresponding to the fiber that has damage would be reduced.

10

What would a Compound AP from a nerve look like if there was a decrease in the conduction velocity of a fiber?

The peak corresponding to the fiber that has damage would shift to the right.

11

What would most likely cause a decrease in conduction velocity of a nerve?

De-myelination. Diseases that cause this include Diabetes, Herpes Zoster. and Guillian-Barre

12

What are the CHARACTERISTICS and PURPOSE of a SLOWLY ADAPTING response?

Characteristics: Fires throughout stimulus: Sustained, unchanging stimulus

Purpose: Pressure and the Shape of Objects

13

What are the CHARACTERISTICS and PURPOSE of a RAPIDLY ADAPTING response?

Characteristics: Fires only when stimulus changes: Fires at the beginning and end of stimulus

Purpose: Impact, motion of objects, on/off stimuli

14

What does SPATIAL RESOLUTION depend on? (2)

1) Receptive field size (smaller = more sensitive and higher spatial resolution)

2) Innervation Density

15

What is a 2-point discrimination threshold?

Minimum distance between two detectable stimuli

16

What are the characteristics of MECHANORECEPTORS? (4)

1) Very sensitive to force (low threshold)
2) Doesn't respond to painful stmiuli
3) Silent without stimulation (doesn't fire without stimulation)
4) Myelinated axons (fast conduction velocity)

17

What are 5 types of mechanoreceptors?

1) Merkel Disks
2) Meisnner's corpuscles
3) Ruffini corpuscles
4) Pacinian Corpuscles
5) Hair follicle receptors

18

What are the following characteristics of MERKEL DISKS?

Type of information encoded?

Fine touch, 2 point discrimination, resolution of texture (bumpy vs smooth)

19

What are the following characteristics of MERKEL DISKS?

Receptive field characteristics (size, number, name)?

Several small, sensitive spots called "Touch Domes"

20

What are the following characteristics of MERKEL DISKS?

Location and skin level?

superficial, high density in finger tips, lips and mouth

21

What are the following characteristics of MERKEL DISKS?

Adaption Response?

Slowly adapting response and the number of action potentials indicates indentation force

22

What are the following characteristics of MERKEL DISKS?

Axon characteristics?

Myelinated, several disks are innervated by a single axon

23

What are the following characteristics of MEISSNER'S CORPUSCLES?

Type of information encoded?

Type of information encoded: Fine touch, 2-point discrimination, senses abrupt changes in edges, bumps, corners of objects

24

What are the following characteristics of MEISSNER'S CORPUSCLES?

Receptive field characteristics (size, number, name)?

single spot

25

What are the following characteristics of MEISSNER'S CORPUSCLES?

Location?

superficial, glabrous skin only, high density in finger tips, lips, mouth

26

What are the following characteristics of MEISSNER'S CORPUSCLES?

Adaption Response?

Rapidly adapting response. Number of action potentials fired indicates the number of times the skin is indented

27

What are the following characteristics of MEISSNER'S CORPUSCLES?

Axon characteristics?

Myelinated, terminal fiber wraps around epithelium so force is easily sensed

28

What are the following characteristics of RUFFINI CORPUSCLES?

Type of information encoded?

Type of information encoded: Stretch of skin, sense gravity force against skin

29

What are the following characteristics of RUFFINI CORPUSCLES?

Receptive field characteristics (size, number, name)?

Receptive field: Large and diffuse

30

What are the following characteristics of RUFFINI CORPUSCLES?

Location?

Location: superficial, Deep in the dermis

31

What are the following characteristics of RUFFINI CORPUSCLES?

Adaption Response?

Adaption Response: slowly adapting response to skin stretch

32

What are the following characteristics of RUFFINI CORPUSCLES?

Axon characteristics?

Type of information encoded: Stretch of skin, sense gravity force against skin

Axon Characteristics: Axon is myelinated, axon surrounds collagen fibrils

33

What are the following characteristics of PACINIAN CORPUSCLES?

Type of information encoded?

Type of information encoded: Tiny (low indentation), high frequency vibrations. Tuning fork, violin string

34

What are the following characteristics of PACINIAN CORPUSCLES?

Receptive field characteristics (size, number, name)?

Receptive field: Very Large, diffuse

35

What are the following characteristics of PACINIAN CORPUSCLES?

Location?

Location: deep in skin

36

What are the following characteristics of PACINIAN CORPUSCLES?

Adaption Response?

Adaption Response: Slowly Adapting response

37

What are the following characteristics of PACINIAN CORPUSCLES?

Axon characteristics?

Axon Characteristics: Myelinated Axon. A large fluid-filled capsule is wrapped around a bare nerve ending

38

What is the optimal frequency and indentation of a Pacinian Corpuscle?

Frequency: 300 hz

Indentation: close to zero

39

What is the optimal frequency and indentation of a Meissner's corpuscle?

Frequency: 50 hz

Indentation: 50 microns

40

What are the following characteristics of a HAIR FOLLICLE RECEPTOR?

Type of information encoded?

Type of information encoded: Velocity of hair movements

41

What are the following characteristics of a HAIR FOLLICLE RECEPTOR?

Receptive field characteristics (size, number, name)?


Receptive field: axon wraps around base of follicle

42

What are the following characteristics of a HAIR FOLLICLE RECEPTOR?

Adaption Response?

Adaption Response: Rapidly adapting response

43

What are the following characteristics of a HAIR FOLLICLE RECEPTOR?

Axon characteristics?

Axon Characteristics: Myelinated

44

What are the following characteristics of a HAIR FOLLICLE RECEPTOR?

Type of information encoded?
Receptive field characteristics (size, number, name)?
Adaption Response?
Axon characteristics?

Type of information encoded: Velocity of hair movements

Receptive field: axon wraps around base of follicle

Adaption Response: Rapidly adapting response

Axon Characteristics: Myelinated

45

Which receptors are the best, and second best, at distinguishing spacing?

1st: Merkel disks
2nd: Meissner's corpuscle

46

What is the Spatial Summation Code:

Overall picture in brain due to sum of information from the pattern of activation of different fibers.

47

What are the following characteristics of a COOLING receptor?

Type of information encoded?

Type of information encoded: Cooling of skin

48

What are the following characteristics of a COOLING receptor?

Receptive field characteristics (size, number, name)?

Receptive field: very small

49

What are the following characteristics of a COOLING receptor?

Location?

Location: Infrequent distribution

50

What are the following characteristics of a COOLING receptor?

Adaption Response?

Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When cooled, action potential frequency increases and are rapidly adapting. Speed of cooling is indicated by frequency of action potentials.

When heated, action potentials decrease in frequency.

51

What are the following characteristics of a COOLING receptor?

Axon characteristics?

Axon Characteristics: free nerve ending and thinly myelinated (Adelta)

52

What are the following characteristics of a WARMING receptor?

Type of information encoded?
Receptive field characteristics (size, number, name)?
Adaption Response?
Axon characteristics?

Type of information encoded: Warming of skin

Receptive field: very small

Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When warmed, action potential frequency increases and are rapidly adapting. Speed of warming is indicated by frequency of action potentials.

When cooled, action potentials decrease in frequency.

Axon Characteristics: free nerve ending and unmyelinated (C fiber)

53

What is the optimal range for a WARMING RECEPTOR?

33-42 degrees C

54

What are the following characteristics of a WARMING receptor?

Axon characteristics?

free nerve ending and unmyelinated (C fiber)

55

What are the following characteristics of a WARMING receptor?

Type of information encoded?

Type of information encoded: Warming of skin

56

What are the following characteristics of a WARMING receptor?

Receptive field characteristics (size, number, name)?

Receptive field: very small

57

What are the following characteristics of a WARMING receptor?

Adaption Response?

Adaption Response: At physiological temperature, the axon fires at 1 hz continuously. When warmed, action potential frequency increases and are rapidly adapting. Speed of warming is indicated by frequency of action potentials.

When cooled, action potentials decrease in frequency.

58

What are the types of Nociceptors? (2)

1) A-mechanonociceptor
2) C Polymodal Nociceptors

59

What are the following characteristics of a A-mechanonociceptor?

Type of information encoded?

Responds to intense force and intense heat. Causes fast pain (sharp, shootng, electrical pricking pain and easy to localize pain)

Includes pain when you stub toe, hit thumb, or and under very hot water

60

What are the following characteristics of a A-mechanonociceptor?

Adaption Response?

Slowly adapting response. Only responds to intense force. Frequency of action potential determines strength of force.

61

What are the following characteristics of a A-mechanonociceptor?

Receptor Field?

Small receptor field

62

What are the following characteristics of a A-mechanonociceptor?

Axon characteristics?

Free nerve endings and axon is myelinated (A-Delta fibers)

63

What are the following characteristics of a C Polymodal nociceptors?

Type of information encoded?

Intense force, high heat (above 45 degrees.) Also responds to chemicals (bradykinin, prostaglandins, histamine, acid)

Slow pain, long lasting, burning, aching, dull pain and it is difficult to localize.

Begins responding at less heat than A mechanoneceptors and can desensitize to high heat.

64

What are the following characteristics of a C Polymodal nociceptors?

Adaption response?

Slowly adapting response. Only responds to intense force. Frequency of action potential determines strength of force.

65

What are the following characteristics of a C Polymodal nociceptors?

Axon Characteristics?

Axon is unmyelinated (C fiber.) Free nerve endings that are accessible to inflammatory chemicals

66

Where are the cell bodies of the 1st neuron of the dorsal column located?

The Dorsal Root Ganglia

67

What type of information do the peripheral processes of the 1st neuron of the dorsal column encode?

Sensory information from mechanoreceptors

68

Where does the 1st neuron of the dorsal column terminate?

In dorsal column nuclei (either nucleus gracilis or nucleus cuneatus)

69

Where are the cell bodies of the 2nd neuron in the dorsal column? (what nucleus and what level of the CNS) (2)

In either:

1) Nucleus gracilis
or
2) Nucleus cuneatus

At the level of the caudal medulla or upper spinal cord

70

Which neuron of the dorsal column decussates and where does this occur?

The 2nd neuron decussates in the caudal medulla

71

What are the fibers that decussate in the dorsal column called?

Internal arcuate fibers

72

What is the medial lemniscus?

The medial lemniscus carries the 2nd neuron of the dorsal column after deccusation

73

Where does the 2nd neuron of the dorsal column (medial lemniscus at this point) terminate?

in the VPL (ventral posterior lateral) of the thalamus

74

Where are the cell bodies of the 3rd neuron of the dorsal column sensory pathway?

VPL of thalamus

75

Where do axons of the 3rd neuron of the sensory pathway go through?

posterior limb of internal capsule

76

Where does the 3rd neuron of the dorsal column sensory pathway terminate?

Terminates in the SI cortex (post-central gyrus/primary somatosensory cortex)

77

Which level contributes to FASCICULUS GRACILIS?

Axons from below T7 (lower limb)

78

Which level contributes to FASCICULUS CUNEATUS?

Axons from above T7 (upper limb)

79

What structure seperates fasciculus gracilis and cuneatus

Posterior Intermediate Septum

80

What levels of the spinal cord will have both fasciculus cuneatus and gracilis?

T7 and below (thoracic after t7, lumbar and sacral regions)

81

What is Posterior Cord Syndrome and what are the symptoms?

Posterior Cord Syndrome occurs usually due to some disease (herpes) that wipe out the dorsal column.

There would be a loss of light touch, pressure, vibration and proprieception from dermatomes below the level of the lesion.

82

What sensory defects relating to the dorsal column would be seen if there was a UNILATERAL SPINAL CORD LESION?

Loss of light touch, pressure, vibration and proprioception IPSILATERALLY and below the lesion.

83

What sensory defects relating to the dorsal column would be seen if there was a LARGE CENTRAL CORD LESION?

Loss of light touch, pressure, vibration and proprioception from dermatomes below the level of the lesion.

However, SACRAL regions would be spared because these neurons are located more dorsal.

84

How is the somatotopy of the dorsal column represented at the levels of Caudal Medulla, Rostral Medulla, and Pons

Caudal Medulla: Ipsilateral, lateral = upper limbs and trunk, medial = lower limbs

Rostral Medulla: contralateral, dorsal = upper limbs and trunk, ventral = lower limbs ("Headless hemi-man standing on pyramids")

Pons: trigeminal n. enters at mid-pons so face is added, otherwise same as rostral medulla

85

What defects would result in a MEDIAL LEMNISCUS LESION?

Loss of light touch, pressure, vibration and proprioception from dermatomes below the level of the lesion on the CONTRA-LATERAL side of body

86

What part of the thalamus transmits fibers involving sensation from the body?

VPL (ventral posterior lateral)

87

What part of the thalamus transmits fibers involving sensation from the face?

VPM (ventral posterior medial)

88

How does the thalamus process sensory neurons from the dorsal column? (2)

1) relays them to the somatosensory cortex

2) can inhibit signals during stress

89

How is the somatotopy of the 3rd neuron in the thalamus represented?

Medial = face (VPM)

Lateral = body (VPL - lower limb most lateral)

90

What is the corona radiata?

Axons that radiate from the thalamus that fan out towards the cortex

91

What does a lesion in the thalamus or SI cortex result?

Loss of sensation from CONTRA-LATERAL side of body

92

What are the broadman areas associated with the SI cortext? (4)

3a, 3b, 1, 2

93

What type of information does Broadman area 3a transmit?

limb movement

94

What type of information does Broadman area 3b transmit?

basic tactile information (edges and texture)

95

What type of information does Broadman area 1 transmit?

motion and direction of movement of objects

96

What type of information does Broadman area 2 transmit?

limb position, shapes of objects

97

What pathway do sensory neurons follow starting from the thalamus?

Thalamus --> SI --> SII --> Inter-piratal sulcus (association cortex) --> Motor cortex

98

Where is SII?

Sylvian fissure and Insula

99

What would a UNIMODAL LESION of the parietal lobe result in?

agnosias (inability to recognize an object or a property of an object)

100

What would a MULTIMODAL LESION of the parietal result in?

contra-lateral neglect

101

What is Anesthesia?

Lack of all sensation

102

What is Analgesia?

Lack of pain

103

What is Athermia?

Lack of thermal sensation

104

What is Hypoalgesia?

Decreased sensitivity to pain

105

What is Hyperesthesia?

Heightened sensitivity to any stimulus

106

What is Paresthesia?

unpleasent, abnormal sensation: tingling, pricking, numbing, stinging, "pins and needles"

107

What is Pruritus?

itching

108

What is Hyperalgesia?

Increased pain from normally painful stimuls

109

What is Allodynia?

Pain from normally non-painful stimulus

110

What is Congenital Insensitivity to pain?

Type 1?
Type 2?

Lack of ability to feel pain. Usually results in early death from accumulated injury.

Type 1: Caused because of lack of access to a required nerve growth factor: nocceptors can't grow

Type 2: Mutation in the gene for voltage gated channels of nocceptors: Nocceptors present but not working

111

What is fibromyalgia?

Trigger points throughout the body trigger bouts of intense pain. Don't know what causes this. Usually seen in women.

112

What is acute pain?

Critical protective function, serves as a warning that injury should be avoided or treated

113

What is chronic pain?

Pain that doesn't go away or adapt. Pain continues after complete healing. Chronic pain serves no useful purpose.

114

What is Nociceptive pain?

Cause:
Type of pain?
Type of fibers?
Mechanism? (2)

Cause: Inflammation of soft tissues
Type of pain: Chronic
Type of fibers: C fibers
Mechanism: Inflammatory chemicals sensitize nociceptors by lowering their threshold; they also send an increased barrage of action potentials to spinal cord

115

What is the treatment for Nociceptive pain? (2)

Mechanism?

Treatement: NSAIDs or opiods

Mechanism: NSAIDs block the synthesis of prosta-glandins from arachodonic acid

116

What chemicals make up he inflamatory response? (6)

Histamine, Bradykinin, 5-HT, Prostaglandin, ATP, H+

117

What is Neuropathic pain?

Cause:
Type of pain?
Symptoms?
Treatement?

Cause: direct damage to nerves in PNS or CNS (cut, compression, loss of blood or oxygen)

Types of pain: Chronic

Symptoms: Incapacitating sharp pain, burning, electrical quality, allodynia

Treatment: anti-anxiety and anti-depression drugs

118

What are examples of causes of Neuropathic pain? (3)

Post herpetic neuralgia after shingles infection
diabetic neuropathy
severe nerve entrapment

119

What type of information is conveyed by the Anterolateral systrem? (2)

Pain and temperature

120

What type of fibers and sensations input into the anterolatera system? (3)

A-delta fibers (fast sharp acute pain)
C-fibers (delayed chronic pain)
Thermo-receptors (non-painful warming and cooling)

121

Where are the cell bodies of nociceptors located?

DRG

122

How do nociceptors enter the spinal cord and where do they synapse?

Enter: via Dorsal lateral tract of Lissaur

Synapse: on second order neurons in the dorsal horn: Lamina 1, 2 or 5

123

What chemicals do first order neurons of nociceptors use to activate receptors of 2nd order neurons? (2)

Release of glutamate and substance P

124

What's a major difference between where primary neurons of the anterolateral tract synapse compared to where primary neurons of the dorsal columns synapse?

Primary neurons of the anterolateral tract synapse in the spinal cord in the dorsal horns of the spinal level where they entered

Primary neurons of the dorsal column tract ascend without synapsing at the level of the spinal cord they entered and synapse in dorsal column nuclei in the caudal medulla

125

What is the initial path of 2nd order neurons of the anterolateral tract?

Cell bodies in the dorsal horn send axons that cross to the contralateral side within 3 segments rostral and ascend in anterolateral tracts (3 main pathways after this).

126

What would a lesion to the anterolateral tracts result in?

Loss of pain and temperature to areas BELOW the lesion on the CONTRALATERAL side.

Loss is complete by 2-3 spinal segments below the lesion

127

What are the names of 3 pathways the 2nd neuron of the anterolateral tract can take and what are their main functions?

1) Spinothalamic tract (Discrimination between pain)
2) Spinoreticular Tract (Attention, arousal, affect)
3) Spinomesencephalic tract (Endogenous pain relief)

128

What are some potential causes for a unilateral spinal injury? (3)

Loss of blood supply (artery compression)
Bone fragment
Disk herniation

129

What is Anterior cord syndrome?

Anterior spinal artery lesion can result in loss of blood supply and damage to tissue in the anterior part of the spinal cord. Most frequently affects the anterolateral tracts

130

What is Central cord syndrome?

Causes? (3)
Symptoms? Where does it affect?

Hole in the center of spinal cord

Causes: Syringomyelia, trauma, tumor

Symptoms: cuts crossing axons of 2nd order neurons that go into anterolateral tracts. Causes bilateral loss of pain and temp. Affects only levels of spinal cord where lesions exist.

131

What is Syringomeylia?

Cavity or cyst in center of spinal cord that can cause Central Cord syndrome

132

Where does the Spinothalamic tract terminate? (2)

2 areas in the thalamus

Ventral Posterior Lateral (VPL) Nucleus
Central Lateral Nucleus

133

What part of the medulla does the spinothalamic tract ascend?

Lateral

134

What type of sensation does the spinothalamic tract mediate?

Mediates discriminative aspects of pain and temperature senses (location, intensity, duration)

135

From where does the VPL of the spinothalamic tract get it's innervation?

Pain info from the body (not neck or head)

136

Where do 3rd order axons of the spinothalamic tract project to after the VPL?

What role do these axons play?

Projections: Axons project to the SI cortext (areas 3b, 1, 2)

Role: Localizes where noxious stimulus on body occurred, how intense and it's quality

137

Where do 3rd order axons of the spinothalamic tract project to after the Central Lateral Nucleus?

What role do these axons play?

Projections: Limbic cortex (cingulate gyrus, hippocampus, amygdala)

Role: Involved in emotional suffering during chronic pain and memory of painful events

138

What are the functions of the thalamus regarding pain?

1) Processing of nociceptive information (crude pain and temp sensations, emotional suffering reactions)

2) Relay information to SI cortex

139

What is the reticular formation?

A long column of nuclei extending from the medulla to the pons. 2nd order pain fibers from the spinoreticular tract terminate here.

140

Where does he spinoreticular tract terminate?

In the reticular formation in medulla and pons

141

What role does he spinoreticular tract play?

Mediates changes in level of attention to painful stimuli. Involved in emotional, arousal, attention, affective response to noxious stimulus. How tied into anxiety the pain is.

142

Where does the 2nd order neurons of the spinomesencephalic tract ascend?

Ascend with the spinothalamic tract up the lateral medulla

143

Where does the spinomesencephalic tract terminate?

Periaqueductal Gray Matter (PAG) in the superior collicululus of the midbrain

144

Where do 3rd order neurons of the spinomesencephalic tract project? (2)

What chemicals do these axons release?

Projection: Descends to spinal cord through 2 nuclei
1) Raphe nuclei in the medulla (Release Seratonin)
2) Locus ceruleus in pons (Release norepinephrin)

Axons from these nuclei descend and synapse on interneurons or spinalthalamic neurons in the spinal cord

145

What is the role of the Insula? (2)

1) Processes info on internal, autonomic state of body (heart races, breathing rapid, mouth dry, muscles tense, can't seep)

2) Integrates discriminative, affective, emotional, cognitive components of pain

146

What would a lesion to the insular cortex cause?

Asymbolia for pain: Patients perceive stimulus as noxious, but don't care. Emotional response to pain is inappropriate (may laugh)

147

What is the role of 3rd order neurons of the spinomesencephalic tract?

descending control pathway that inhibit pain signals, provides a negative feedback loop for pain

148

Where does morphine act in the nervous system?

Morphine activates cells in the PAG, activating descending inhibitory pathways that inhibit pain

149

Where does the common pathway begin for pain and temperature coming from the periphery and visceral pain?

2nd order neurons of the spinothalamic tract in the dorsal horn

150

Where is pain referred to for pain coming from the Diaphragm?

C3-C4

151

Where is pain referred to for pain coming from the Heart? Side?

T1-T4 (left)

152

Where is pain referred to for pain coming from the Stomach? Side?

T6-T9 (left)

153

Where is pain referred to for pain coming from the Gallbladder? Side?

T7-T8 (right)

154

Where is pain referred to for pain coming from the Duodenum?

T9-T10

155

Where is pain referred to for pain coming from the Appendix? Side?

T10 (right)

156

Where is pain referred to for pain coming from the Reproductive organs?

T10-T12

157

Where is pain referred to for pain coming from the Kidney/ureter?

L1-L2

158

Where does the trigeminal ganglia enter the brainstem?

Ventrolateral pons

159

Where do 1st order nuerons for FINE/DISCRIMINATIVE TOUCH from the trigeminal ganglia synapse?

Main sensory nucleus in pons (chief nucleus V)

160

Where do 1st order neurons for PAIN AND TEMPERATURE from the trigeminal ganglia synapse?

Spinal trigeminal nucleus - long column from pons to cervical cord

161

Where do 2nd order neurons from the main sensory nucleus project to?

VPM

162

Where do 2nd order neurons from the spinal trigeminal nucleus project to?

VPM

163

What is the somatatopy of the VPM

Tongue = medial
Oral Cavity = middle of VPM
Face = lateral

164

What is the pathway of 2nd order neurons conveying fine touch from the face?

Cell body?
Pathway?
Synapse?

Cell bodies: Chief Nucleus V

Pathway: Axons decussate and ascend via the Trigeminal Leminscus to the VPM of the thalamus

Synapse: 3rd order neurons

165

What is the trigeminal leminscus and what does it run with?

The trigeminal leminscus is the pathway of 2nd order neurons conveying fine touch sensation from the face/trigeminal ganglion.

It runs with the Medial Lemniscus

166

Where do 3rd order neurons of the trigeminal system projecting fine/discriminative touch project to?

Lateral SI cortex (near lateral fissure)

167

Where do axons projecting fine touch from the face decussate?

2nd order neurons of the trigeminal system coming from Chief nucleus V decussate at the level of the pons.

168

What is a minor pathway for crude touch coming from the face?

1st order neuron: cell body in the trigeminal ganglion send axons to the chief nucleus V where they DO NOT synapse. Axons descend via Spinal tract V and synapse on spinal nucleus V at the caudal medulla

2nd order neuron: axons decussate and ascend as the trigeminal lemniscus to VPM

169

What is the pathway for 1st order neurons coming from the oral cavity conveying FINE TOUCH?

Cell bodies?
Synapse?

Cell bodies: trigeminal ganglion

Synapses: on 2nd order neurons in the Chief nucleus V

170

What is the pathway for 2nd order neurons coming from the oral cavity conveying FINE TOUCH?

Cell bodies?
Pathway?
Synapse?

Cell bodies: Chief Nucleus V

Pathway: SOME neurons cross to the contralateral side and ascend via the Dorsal trigeminal tract, and SOME neurons ascend without crossing

Synapse: Synapses on 3rd order neurons in the VPM on both sides

171

What is the pathway for 1st order neurons coming from the face conveying PAIN AND TEMPERATURE?

Cell bodies?
Pathway?
Synapse?

Cell bodies: Trigeminal ganglion

Pathway: axons enter the pons project descend ipsilaterally via Spinal Trigeminal Tract V

Synapse: axons synapse all along the Trigeminal Nucleus V

172

What is he Trigeminal Nucleus V?

What cell bodies are there?
Location?

Cell bodies: 2nd order neurons conveying pain and temperature from the face

Location: long column from he pons to cervical cord

173

What is the pathway for 2nd order neurons coming from the face conveying PAIN AND TEMPERATURE?

Cell bodies?
Pathway?
Synapse?

Cell bodies: Trigeminal Nucleus V

Pathway: Axons decussate and ascend via Trigeminothalamic tract

Synapse: Terminates in VPM of thalamus

174

What is the Trigeminothalamic tract and what tract does it run alongside?

Contains 2nd order neurons conveying pain and temperature from the face.

Runs alongside the spinothalamic tract

175

What is Trigeminal neuralgia "tic douloureux"?

Location?
Provoked?
Treatment?

Intense pain

Location: V2/V3 territory
Provocation: chewing, shaving, brushing teeth, touching trigger points
Treatment: carbamazepine (reduces excitability of neurons by working on NA+ channels): also sometimes anti-depressants

176

What is Tempromandibular jointdisorder (TMD)

Symptoms?
Cause? (5)
Treatment? (3)

Symptoms: chronic pain in joint of jaw, muscles of mastication, recurrent headaches, ear pain

Cause: Teeth grinding and clenching at night (also gum chewing, fingernail biting, trauma to jaw)

Treatment: mouth guard, NSAIDS, Stress management