Neuro Ch. 7 one-liners Flashcards
1
Q
Function of posterior column pathway:
A
Convey proprioception, vibration, and fine, disciminative touch
2
Q
Name of the posterior column’s secondary neuron pathway?
A
medial lemniscal pathway
3
Q
Where does the posterior column pathway decussate?
A
internal arcuate fibers of the lower medulla
4
Q
Where do primary neurons of the posterior column synapse?
A
posterior dorsal column nuclei in the medulla
- gracile nucleus
- cuneate nucleus
5
Q
Where do secondary neurons/medial lemniscus of the posterior column synapse?
A
VPL (ventral posterior lateral nucleus) of thalamus
6
Q
Where does the posterior column pathway ascend?
A
ipsilaterally in the posterior/dorsal column white matter, until the medulla, where it decussates, then contralaterally to the thalamus VPL
7
Q
Main tract of the anterolateral pathway
A
spinothalamic tract
8
Q
Function of anterolateral pathway
A
senses pain, temperature, and crude touch
9
Q
Where does the anterolateral pathway decussate?
A
anterior commissure of the spinal cord (immediately as it enters); takes 2-3 segments to cross
10
Q
Where does the anterolateral pathway ascend?
A
contralaterally in the spinothalamic tract of the anterolateral white matter, until it reaches its synapse in the VPL of the thalamus
11
Q
What sensory receptor is involved in the stretch reflex?
A
muscle spindles - which sense the amount and rate of stretch
12
Q
How is touch affected in an isolated lesion to the posterior column?
A
Touch sensation will not be eliminated because touch is carried by both the posterior (fine, descriminative) and anterolateral (crude) columns
13
Q
How is touch affected in an isolated lesion to the anterolateral column?
A
Touch sensation will not be eliminated because touch is carried by both the posterior (fine, descriminative) and anterolateral (crude) columns
14
Q
Where are the cell bodies of sensory neurons located?
A
Dorsal root ganglia
15
Q
What is a dermatome?
A
A peripheral region innervated by sensory fibers from a single nerve root level
16
Q
What sensory neurons fibers are associated with proprioception, and what is their associated receptor?
A
A-alpha (muscle spindle and golgi tendon organ receptors)
A-beta (Muscle spindle receptors)
17
Q
What sensory neuron fibers and receptors are associated with deep touch and vibration?
A
A-beta (pacinian corpuscles and ruffini endings)
18
Q
What neuron fibers and receptors are associated with touch and vibration?
A
A-beta (hair receptor)
19
Q
What sensory neuron fibers and receptors are associated with superficial touch?
A
A-beta (Meissner’s corpuscles and merkel’s receptor)
20
Q
What sensory neuron fibers are associated with pain, and what is their associated receptor?
A
A-delta (bare nerve ending)
C (bare nerve ending)
21
Q
What sensory neuron fiber and receptor is associated with cool temperature?
A
A-delta (bare nerve ending)
22
Q
What sensory neuron fiber and receptor is associated with warm temperature?
A
C (bare nerve ending)
23
Q
What sensory neuron fibers and receptors are associated with itch?
A
A-delta (bare nerve ending)
C (bare nerve ending)
24
Q
Which sensory neuron fiber types are myelinated?
A
A-alpha, A-beta, and A-delta (*all the A’s)
25
Which sensory neuron fiber types are unmyelinated?
C (C fibers are the outCasts)
26
What type of axons conduct faster?
larger-diameter, myelinated
27
Describe the somatotopic organization of the posterior column pathway:
dorsal/posterior columns: of the spinal cord; legs and lower trunk medially in fasciculus gracilis, and upper trunk above T6, arms, and neck laterally in the fasciculus cuneatus
medulla: medial lemniscus is vertical in medulla with feet ventrally (then lower trunk, upper trunk, arms, neck)
pons and midbrain: the medial lemniscus lies back down reversing position; arms medially and legs laterally
28
What pathway is analogous to the medial lemnisual pathway?
Trigeminal leminiscus conveying touch from face, but goes to VPM
29
What types of axons are found in the posterior column pathway?
larger-diameter, myelinated
30
What types of axons are found in the anterolateral pathway?
smaller-diamter, unmyelinated (conveying pain and temperature)
31
What is Lissauer's tract?
Some axon collaterals from the anteriolateral pathway first ascend or descend for a few segments through this tract before entering gray matter
32
What pathway is analogous to the spinothalamic tract?
trigeminothalamic tract sensing pain and temperature of face (CN V)
33
What are the three tracts of the anterolateral pathway?
spinothalamic, spinoreticular, and spinomesencephalic
34
what is the function of the spinothatlmic tract and where does it synapse?
disciminative aspects of pain and temperature sensation: location and intensity (synapses in VPL); also with spinoreticular for emotional and arousal aspects of pain (to intralaminar thalamic/central lateral nucleus and mediodorsal nuclei)
35
What is the function of the spinoreticular tract and where does it synapse?
emotional arousal aspects of pain; intralaminar thalamic nuclei/central lateral nuclesu and mediodorsal nuclei
36
Where do the intralaminar nuclei project?
diffusely to entire cerebral cortex; involved in behavioral arousal
37
What is the function of the spinomesencephalic tract and where does it project?
central modulation of pain; projects to periaqueductal gray matter and superior colliculus
38
From where does the spinothalamic tract arise?
Laminae I and V
39
From where does the spinoreticular tract arise?
diffusely from lamina VI-VIII (intermediate zone and ventral horn)
40
From where does the spinomesencephalic tract arise?
laminae I and V
41
What is cortical sensory loss?
characteristic deficits associated with lesions of the somatosensory cortex and adjacent regions
42
Where is the secondary somatosensory association cortex located?
in the parietal operculum (along the superior margin of the Sylvian fissure)
43
Where is the sensory association cortex located?
in the superior parietal lobule (Brodmann's 5 and 7)
44
What sensory fibers are involved in pain modulation?
large-diameter A-beta
45
How do TENS devices work to control chronic pain?
gate-control theory: A-beta fibers reduce pain transmission through the dorsal horn
46
Role of serotonergic (5-HT) neurons?
from RVM raphe nucleus project to spinal cord for modulation of pain in the dorsal horn
47
Role of supbstance P?
neuropeptide from RVM neurons to mediate locus ceruleus
48
NE neurons in pain modulation?
from locus ceruleus to dorsal horn
49
Hisamine contributes to pain modulation
through H3 receptors
50
What are the endogenous opiate peptides?
enkephalin, Beta-endorphin, and dynorphin
51
Where are enkephalin neurons found in high concentrations?
periaqueductal gray matter, RVM, and spinal cord dorsal horn
52
Where are dynorphin neurons found in high concentrations?
periaqueductal gray matter, RVM, and spinal cord dorsal horn
53
Where are Beta-endorphin neurons concentrated?
regions of the hypothalamus that project to the periaqueductal gray
54
Which have a greater number of projections - corticothalamic or thalamocortical?
corticothalamic
55
What forms the diencephalon?
thalamus, hypothalamus, and epithalamus
56
What is the internal medullary lamina?
Y-shaped white matter that divides the thalamus into medial, lateral, and anterior nuclear groups
57
Where are intralaminar nuclei located?
In the internal medullary lamina
58
What is the thalamic reticular nucleus?
forms an extensive thin sheet envoloping the lateral aspect of the thalamus
59
What nuclei does the epithalamus consist of?
several small nuclei, including habenula, parts of pretectum, and pineal body
60
What are the three main categories of thalamic nuclei?
Relay, intralminar, and reticular; see table 7.3 for details of each
61
Where are the midline nuclei located?
A thin collection of nuclei lying adjacent to the third ventricle (several are continuous with and functionally similar to the intralaminar nuclei
62
The thalamus is mostly made up of which type of nuclei?
Relay nuclei
63
Which of the relay nuclei are the most localized?
projections to the primary sensory and motor areas (VPL, VPM, LGN, MGN, VL)
64
Which thalamic nuclei is just medial to the internal capsule?
Reticular Nucleus
65
Which thalamic nuclei does not project to the cortex?
Reticular nucleus only
66
Which thalamic nuclie contains primarily GABAergic neurons?
Reticular nucleus
67
Which thalamic nucleus is involved in thalamic regulation?
Reticular nucleus
68
Which thalamic nuclei relays somatosensory spinal inputs to the cortex?
Ventral posterior lateral nucleus (VPL)
69
Which thalamic nucleus relays somatosensory CN inputs and taste to the cortex?
Ventral posteromedial nucleus (VPM)
70
Which thalamic nucleus relays visual inputs to the cortex?
lateral geniculate nucleus (LGN)
71
Which thalamic nucleus relays auditory inputs to the cortex?
medial geniculate nucleus (MGN)
72
Which thalamic nuclei relays basal ganglia and cerebellar inputs to the cortex?
ventral lateral (VL) and ventral anterior (VA) nuclei
73
which thalamic nucleus relays behavioral orientation toward relvant visual and other stimuli?
puvlinar nucleus
74
Which thalamic nuclei functions with anterior nuclei?
lateral dorsal nucleus
75
which thalamic nuclei functions with pulvinar nucleus?
lateral posterior nucleus
76
which thalamic nucleus helps to maintain alert, conscious state?
ventral medial nucleus and rostral intralaminar nuclei
77
which thalamic nuclei are involved with projecting limbic pathways and cognitive functions?
mediodorsal nucleus (MD), anerior nuclear group (anterior nucleus), and midline thalamic nuclei
78
which thalamic nuclei are involved with motor relay for basal ganglia?
caudal intralaminar nuclei
79
What sensory modality does not have a relay nucleus in the lateral thalamus?
olfaction
80
Inputs of VPL
medial lemniscus and spinothalamic tract
81
outputs of VPL
somatosensory cortex
82
inputs of VPM
trigeminal leminiscus, trigeminothalamic tract, taste inputs
83
outputs of VPM
somatosensory and taste cortex
84
intputs of lateral geniculate nucleus (LGN)
retina
85
outputs of lateral geniculate nucleus (LGN)
primary visual cortex
86
Inputs of medial geniculate nucleus (MGN)
inferior colliculus (auditory info)
87
Outputs of MGN (medial geniculate nucleus)
primary auditory cortex
88
inputs of VL (ventral lateral nucleus)
motor pathways leaving cerebellum and basal ganglia:
| internal globus pallidus, deep cerebellar nuclei, substantia nigra pars reticulata
89
Outputs of VL (ventral lateral nucleus)
motor, premotor, and supplementary motor cortex
90
Inputs of VA (ventral anterior nucleus)
substantia nigra pars reticulata
internal globus pallidus
deep cerebellar nuclei
91
Outputs of VA (ventral anterior nucleus)
Widespread to frontal lobe, including prefrontal, premotor, motor, and supplementary motor cortex
92
Inputs of pulvinar nucleus
tectum (extrageniculate visula pathway), other sensory inputs
93
Outputs of pulvinar nucleus
parietotemporo-occipital association
94
Inputs of lateral dorsal nucleus
limbic pathways; mammillary body, hippocampal formation
95
Outputs of lateral dorsal nucleus
anterior cingulate gyrus
96
Inputs of lateral posterior nucleus
tectum (extrageniculate visula pathway), other sensory inputs
97
Outputs of lateral posterior nucleus
parietotemporo-occipital association
98
Inputs of ventral medial nucleus
midbrain reticular formation
99
Outputs of ventral medial nucleus
widespread to cortex
100
What is the main nucleus of the medial nuclear group?
mediodorsal nucleus (MD)/dorsomedial nucleus
101
Inputs of the medial nucleuar group/MD
amygdala, olfactory cortex, limbic basal ganglia
102
Outputs of the medial nuclear group/MD
frontal cortex
103
Main nucleus of the anterior nuclear group
Anterior nucleus
104
Inputs of the anterior nuclear group/anterior nucleus
limbic pathways: mammillary body, hippocampal formation
105
Outputs of the anterior nuclear group/anterior nucleus
anterior cingulate gyrus
106
What are the midline thalamic nuclei?
Paraventricular, parateaenial, interanteromedial, intermediodorsal, rhomboid, reuniens (medial ventral)
107
Main inputs for the midline thalmic nuclei
hypothalamus, basal forebrain, amygdala, hippocampus
108
Outputs for the midline thalamic nuclei
amygdala, hippocampus, limbic cortex
109
What are the intralaminar nuclei?
rostral and caudal intralaminar nuclei (main inputs and outputs are from the basal ganglia)
110
What are the rostal intralaminar nuclei?
central medial nucleus, paracentral nucleus, central lateral nucleus
111
Inputs of the rostral intralaminar nuclei?
(basal ganglia); deep cerebllar nuclei, globus pallidus, brainstem ascending reticular activating systems (ARAS), sensory pathways
112
Outputs of the rostral intralaminar nuclei?
(basal ganglia); cerebral cortex, striatum
113
What are the caudal intralaminar nuceli?
centromedian nucleus, parafascicular nucleus
114
Inputs of the caudal intralaminar nuclei
(basal ganglia); globus pallidus, ARAS (ascending reticular activating systems), sensory pathways
115
Outputs of the caudal intralaminar nuceli
(basal ganglia); striatum, cerebral cortex
116
Inputs of the reticular nucleus
cerebral cortex, thalamic relay and intralaminar nuceli, ARAS (ascending reticular activating systems)
117
Outputs of the reticular nucleus
thalamic relay and intralaminar nuclei, ARAS (ascending reticular activating systems), *the only thalamic nuclei that doesn't project to the cortex
118
What occurs with lesions of somatosensory pathways?
sensory loss or paresthesias
119
Paresthesias associated with lesions to the posterior column-medial lemniscal pathway
tingling, numb sensation
tight, bandlike sensation around trunk or limbs
sensation similar to gauze around fingers with palpation
120
Paresthesias associated with lesions to the anterolateral pathways
sharp, burning, or searing pain
121
Paresthesias associated with lesions to the parietal lobe
contralateral numb tingling, pain can also be prominent
122
Paresthesias associated with lesions to the primary sensory cortex
contralateral numb tingling, pain can also be prominent
123
Paresthesias associated with lesions to the thalamus
Dejerine-Roussy syndrome (severe contralateral pain)
124
Dejerine-Roussy syndrome
associated with lesions of the thalamus; severe contralateral pain
125
Paresthesias associated with lesions to the C-spine
Lhermitte's sign (electricity-like ensation running down the back and into the extremities upon neck flexion)
126
Lhermitte's sign
electricity-like ensation running down the back and into the extremities upon neck flexion; associated with lesions to the C-spin
127
Paresthesias associated with lesions to nerve roots
radicular pain - radiates down the limb in a dermatomal distributsion, accompanied by numbness and tingling, provoekd by movements that stretch the nerve root
128
Paresthesias associated with peripheral nerve lesions
numbness, tingling, and pain in the sensory distribution of the nerve
129
Dysesthesia
unpleasant, abnormal sensation
130
allodynia
painful sensations provoked by normally nonpainful stimuli (like light touch)
131
Hyperpathia
enhanced pain to normally painful stimuli
132
Hyperalgesia
enhanced pain to normally painful stimuli
133
hypesthesia
decreased sensation
134
What are the most common causes of spinal cord dysfunction?
extrinsic compression due to degenerative disease of the spine
trauma
metastatic cancer
135
Where must you image with an MRI if you suspect spinal cord lesions?
cervical and thoracic (and suspected level); soemtimes lesions may be higher than level suggested by sensory or motor levels involved
136
What is spinal shock?
occurs in cases of acute, severe spinal cord lesions (such as trauma);
- flaccid paralysis below the lesion
- decreased sympathetic outflow to vascular SM - decreases BP
- absent sphincteric reflexes and tone
- after weeks-months, UMN signs develop and sphincteric and erectile reflexes may return, although without voluntary control
137
What may inprove the outcome of traumatic spinal cord lesions?
treating within the first 8 hours with high doses of steroids
138
In what spinal regions is chronic myelopathy most commonly seen?
cervical and lumbar
139
What commonly causes chronic myelopathy?
degenerative disorders of the spine
140
Does chronic myelopathy caused by degenerative disorders cuase UMN or LMN signs?
both - b/c both spine and nerve roots are often compressed; sometimes mimicking motor neuron disease
141
What is the most common cause of neoplastic spinal cord compression?
metastic spread to the epidural space (spinal cord tumors can also be seen)
142
What artery is commonly involve in infarction of the spinal cord?
anterior spinal artery occlusion, causing anterior cord syndrome
143
What results in anterior cord syndrome
Spinal cord infarction caused by anterior spinal artery occlusion
144
How do you prevent irreversible loss of ambulation in cord compression caused by tumors?
prompt treatment with radiation and/or surgical intervention (rule of thumb = 80%)
145
What are common causes of spinal cord infarction?
anterior spinal artery occlusion, trauma, aortic dissection, thromboemboli, disc emboli, watershed infarction (T4-T8), spinal dural AVM
146
How does myelitis present?
quick development, hours to days
147
What does MRI show in myelitis?
T2 bright areas
148
What does CS ften show in myelitis?
elevated WBC - usually lmymphocytic-predominant
149
What are common causes of infectious myelitis?
viral (HIV), lyme disease, tertiary syphilic, tropical spastic paraperesis, schistosomiasis
150
What are common causes of inflammatory myelitis?
MS, SLE, postinfectious myelitis
151
What are causes of nutritional spinal cord dysfunctions?
Vitamin B12 and Vitamin E deficiencies
152
What are examples of neoplastic spinal cord dysfunctions?
epidural metastasis, meningioma, schwannoma, carcinomatous meningitis, astrocytoma, ependymoma, hemangioblastoma
153
What are examples of degenerative/developmental spinal cord dysfunctions?
spina bifida, chiari malformation, syringomyelia
154
What are examples of tramatic or mechanical spinal cord dysfunctions?
contusion, compression, disc herniation, degenerative disorders of vertebral bones, disc embolus
155
What are examples of vascular spinal cord dysfunctions?
anterior spinal artery infarct, watershed infarct, spinal dural AVM, epidural hematoma
156
Pattern fo primary somoatosensory cortex deficits
contralateral sensory loss - with discriminative touch andpropriosenation most severely affected (all modalities may be involved)
cortical sensory loss may be present with primary modalities spared
associated deficits of adjacent cortical areas: UMN weakness, visual field deficits, aphasia
157
Pattern for thalamic VPL, VPM, or thalamic somatosensory radiation deficits
contralteral sensory loss (not neatly at midline) of all sensory modalities
sometimes no motor deficit
more noticable in: face (lips), hand (fingertips), and foot (rather than trunk and proximal extremities)
associated deficits: hemiparesis or hemianopia (internal capsule, lateral geniculate, or optic radiations invovlement), hemisensory loss with hemiparesis (somatosensory radiation proximity to corticobulbar and corticopsinal fibers), less commonly midbrain or upper pons cause contralateral face, arm, and leg somatosensory deficits
158
What might be some associated deficits of primary somatosensory cortex lesions
adjacent cortical areas: UMN weakness, visual field deficits, aphasia
159
What might be some associated deficits of thalamic lesions
hemiparesis or hemianopia (internal capsule, lateral geniculate, or optic radiations invovlement), hemisensory loss with hemiparesis (somatosensory radiation proximity to corticobulbar and corticopsinal fibers), less commonly midbrain or upper pons cause contralateral face, arm, and leg somatosensory deficits
160
What pathways are involved in lesions to the lateral pons?
anterolateral pathways and spinal trigeminal nucleus of the same side
161
What pathways are involved in lesions to the lateral medulla?
anterolateral pathways and spinal trigeminal nucleus of the same side
162
What deficit is seen in lesions involving the lateral pons?
loss of pain and termperature to the ipsilateral face and contralateral body
163
What deficit is seen in lesions involving the lateral medulla?
loss of pain and termperature to the ipsilateral face and contralateral body
164
what pathways are involved in lesions to the medial medulla?
medial lemniscus
165
what associated deficits are seen in lesions to the lateral pons?
lateral pontine syndrome
166
what associated deficits are seen in lesions to the lateral medulla?
lateral medullary syndrome
167
What deficits are seen in lesions to the medial medulla?
contralateral loss of vibration and joint position to the body
168
What is the associated deficit of lesions to the medial medulla?
medial medullary syndrome
169
What deficit is seen in distal symmetrical polyneuropathies?
bilateral sensory loss is a "glove and stocking" distribution
170
What deficit is seen in specific nerve or root lesions?
sensory loss to specific territories
171
What are associated deficits of lesions of peripheral nerves or roots?
LMN-type weakness
172
What spinal cord lesion causes partial or complete interruption to all sensory and motor pathways?
transverse cord lesions
173
What are common causes of transverse cord lesions?
trauma, tumors, MS, transverse myelitis
174
What spinal cord lesion causes ipsilateral UMN weakness, ipsilateral loss of vibration and proprioception, ipsilateral 1-2 segments of pain and temperature loss, and contralateral loss of pain and temperature?
Hemicord lesions; Brown-Sequard Syndrome
175
What causes the ipsilateral pain and temperature loss of 1-2 segments in Brown-Sequard Syndrome?
damage to posterior horn cells before their axons cross
176
What are common causes of Brown-Sequard syndrome?
penetrating injuries, MS, lateral compression from tumors
177
What spinal cord lesions involves sacral sparing?
large central cord lesions
178
what spinal cord lesion is involved with cape distribution of pain and temperature loss?
small C-spine central cord lesions
179
what spinal cord lesions is involved in bilateral suspended sensory loss to pain and temperature?
small central cord lesions
180
What are common causes of central cord lesions?
spinal cord contusion, syringomyelia (non or post-traumatic), intrinsic spinal cord tumors (hemangioblastoma, ependymoma, or astrocytoma)
181
What spinal cord lesion is involved with loss of vibration and propioception?
posterior cord lesions
182
What are common causes of posterior cord lesions?
trauma, compression from posteriorly located tumors, MS, Vit B12 def, tabes dorsalis
183
What would be an additional affect of a large posterior cord lesion?
involvement of corticospinal tract causing UMN weakness
184
What spinal cord lesion is involved with weakness, loss of pain and temperature, and incontinence?
anterior cord syndromes
185
What would be an additional deficit of a large anterior cord lesion?
involvement of corticospinal tract causing UMN weakness
186
What spinal cord lesion is often associated with incontience?
anterior cord lesions
187
What are common causes of anterior cord lesions?
trauma, MS, anterior spinal artery infarct
188
What preferentially affects the posterior cord?
Vitamin B12 deficiency and tabes dorsalis (tertiary syphilis)
189
What spinal levels are involved in sensory info from the rectum, bladder, urethra, and genitalia?
S2-S4
190
What are the sacral motor nuclei?
sacral parasympathetic nuclei, onuf's nucleus, and anterior horn cells
191
What is the function of Onuf's nucleus?
provides somatic innervation of urethral and external anal sphincters, and somatic motor pathway for ejection of semen
192
What are the nerve roots for Onuf's nucleus?
S3 (urethral sphincte), S4 (external anal sphincter)
193
What is the function of the sacral parasympathetic nuclei?
parasympathetic innervation to the detrucor muscle, internal anal sphincter, descending colon, rectum, bartholin's glands, and erectile pathway
194
What are the nerve roots of the sacral parasympathetic nuclei?
S2-S4; (S2 esp for erection)
195
What is the funciton of the anterior horn cells?
somatic innervation of the pelvic floor muscles, somatic motor pathway for ejection of semen
196
What are the nerve roots for the anterior horn cells?
S2-S4
197
What is the function of the dorsal motor nucleus of vagus?
parasympathetic innervation of the gut above the splenic flexure
198
What are the nerve roots of the dorsal motor nucleus of vagus?
CN X
199
What initiates the detrusor/voiding reflex?
descending pathways from medial frontal micturition centers after a feeling of bladder fulness reaches the sensory cortex
200
What mediates the detrusor reflex?
intrinsic spinal cord circuits
201
What regulates the detrusor reflex?
the pontine micturition center; also possibly cerebellar and basal ganglia pathways
202
What is the urethral reflex?
when urine flow stops, the urethral sphincters contract, which triggers detrusor relaxation
203
What is triggered by voluntary relaxation of the external uerthral sphincter?
inhibition of sympathetics to the bladder neck, causing it to relax
activation of parasympathetics, causing detrusor muscle contraction
204
What is the affect of the sensation of urine flow through the urethra?
Activation of continued sphincter relaxation and dtrusor contraction
205
How can urine flow be interrupted?
voluntary closure of the urethral sphincter, which triggers detrusor relaxation
206
What occurs with lesions affecting bilateral medial frontal micturition centers?
frontal-type incontinence: reflex activation of pontine and spinal micturition cneters when the bladder is full - normal but not voluntary; pt may or may not be aware of incontinence
207
What are common causes of frontal-type incontinence?
hyrdocephalus, parasagital meningioma, bifrontal glioblastoma, traumatic brain injury, neurodegenerative disorders
