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ascending sensory system Flashcards

1
Q

what are the 5 ascending systems

A

medial lemniscus pathway (posterior column), spinothalamic tract (anterolateral pathway), posterior spinocerebellar tract, cuneocerebellar tract, anterior spinocerebellar tract

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2
Q

three types of fibers in the ascending and descending pathways

A

long ascending fibers: going to thalamus, cerebellum or various brainstem nuclei

long descending fibers: going from cerebellar cortex or various brainstem nuclei to spinal cord gray matter

short propriospinal fibers: interconnecting different spinal cord lees. helps coordinate flexor reflexes

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3
Q

where are ascending tracts found

A

all three funiculi: anterior funiculi, lateral funiculi, and posterior funiculi

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4
Q

Descending tracts are primarily located in?

A

the anterior funiculi and the lateral funiculi

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5
Q

propriospinal fibers are found in

A

they surround the spinal cord gray matter

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6
Q

Somatosensory Receptors detect?

A

mechanical, chemical or thermal changes

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7
Q

Somatosensory receptor neurons?

A

all pseudiunipolar. Cell bodies are int the dorsal root ganglion or cranial nerve ganglion.

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8
Q

Where are somatosensory central processes and peripheral processes

A

Central: a central CNS process in the spinal cord or brainstem
Peripheral process: endings in the skin muscle or joint

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9
Q

merkel endings

A

discriminative touch

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10
Q

free nerve endings

A

pain, temperature, itch , touch

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11
Q

meissners corpuscle

A

discriminative touch (2 point discrimination)

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12
Q

cuneate tubercle

A

camp on back of the brainstem that contains the cuneate nucleus. components of the dorsal column medial lemniscus

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13
Q

Gracile tubercle

A

bump on back of brainstem that contains the gracile nuclei. 2nd order neurons that participates in the posterior column medial lemniscus pathway

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14
Q

in the medulla what is the orientation of the medial lemniscus

A

vertical

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15
Q

in the pons what is the orientation of the medial lemniscus

A

horizontal

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16
Q

medial lemniscus is responsible for what?

A

discriminative touch, 2 point discrimination, conscious proprioception and vibratory sense

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17
Q

what types of fibers are in the medial lemniscus

A

ascending, large, myelinated, primary afferent fives. mechanoreceptors

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18
Q

where does the posterior column medial lemniscus pathway synapse

A

synapses in medulla and then decussates to form medial lemniscus

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19
Q

where does the medial lemniscus relay

A

the lateral thalamus (ventral posterolateral nucleus)

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20
Q

where does the medial lemniscus terminate

A

postcentral gyrus

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21
Q

spinal afferents have their cell bodies?

A

in the ipsilateral dorsal root ganglion

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22
Q

dorsal root ganglion rootlets enter the spinal cord and divide it into two divisions? what are the divisions?

A

medial- heavily myelinated, large, enter posterior column and ascend to brainstem

lateral- finely myelinated and unmyelinated, small

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23
Q

at what level do fibers stop adding to fasiculus gracilis?

A

T6 and fasiculus cuneatus starts to form

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24
Q

when fibers enter the medial lemniscus pathway they are added…?

A

laterally so a pattern of lamination develops (sacral levels most medial and cervical levels most lateral)

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25
where do the posterior column media lemniscus pathway fibers synapse
when they reach the caudal medulla they synapse in the nuclei gracilis and cuneatus (posterior columns) and synapse in VPL
26
what do second order fibers in the posterior column medial lemniscus pathway do?
cross the midline with in the caudal medulla and form the medial lemniscus
27
what do third order fibers in the posterior column media lemnsicus pathway do?
originate in the thalamus )(venture posterolateral nucleus) and ascend through internal capsule to synapse in the primary somatosensory cortex in the post central gyrus
28
injury to medial lemniscus pathway leads to?
impaired proprioception and discriminative tactile functions, especially complex.
29
how can you test for injury in the medial lemniscus pathway
place a vibrating tuning for on body surface or have patient id a pattern drawn on their skin
30
ataxia
uncoordinated movements as brain is unable to direct motor activity without feedback from body cause by injury to posterior column and medial lemniscus pathway
31
where does the medial lemniscus pathway decussate
caudal medulla
32
sensory info reaches brain in ___pathways
multiple pathways. so damage to single pathway rarely leads to total loss of function
33
does injury to the posterior column cause total loss of function forever
No. there will be a large deficit at first but recovery over time is possible
34
the one sense that will stay impaired after injury to posterior column media lemniscus pathway
ability to discriminated complex shape of object (stereognosis) or the direction or speed of the stimulus moving across the skin
35
spinothalamic tract is also called
anterolateral pathway
36
spinothalamic tract is responsible for what?
pain and temperature. awareness is localizing pain
37
the spinothalamic tract terminated in the...
ventral posterolatereal nucleus (VPL) of the thalamus Other fibers in the pathway: end in the reticular formation of the limbic system
38
where do the spinothalamic fibers enter the spinal cord
lateral division of dorsal root (lissauer's tract)
39
where do the second order neurons of the spinothalamic tract synapse
the substantial gelatinosa
40
where does the spinothalamic tract decussate
two levels about which they entered: ascends as its crossing in the ANTERIOR COMMISSURE in the cord
41
when the spinothalamic fibers decussate where do they go to
the anterolateral part of the spinal cord
42
where are the 1st order neurons in the spinothalamic tract
dorsal root ganglions (lissauer's tract)
43
where are the 3 places the spinothalamic tract sends extensions to? and where are they located
1. reticular formation: caudal medulla 2. central gray matter near the cerebral aqueduct in the rostral midbrain 3. postcentral gyrus in the brain
44
Where are the spinothalamic tract 2nd order neurons
in the posterior horn.
45
how do 2nd order neurons in the spinothalamic tract move
cross the midline with a ROSTRAL INClNATION and collect to form the pathways
46
where do new fibers join the the spinothalamic tract
the anteromedial edge
47
somatotopic organization of spinothalamic tract
caudal body parts: posterolateral portion rostral body parts: anteromedial portion
48
where do other spinothalamic fibers project
intralaminar nuclei and other thalamic nuclei
49
the spinothalamic fibers projected to the brainstem reticular formation are important for?
changes in the level of attention of pain response
50
spinomesencephalic fibers are important in?
pain control mechanisms
51
spinohypothalamic fibers mediate what?
autonomic response to pain
52
damage to spinothalamic tract causes?
loss of pain, temperature, itch, and tickle sensations
53
why are there no changes to bowel and bladder pressure and sexual sensations when you damage the spinothalamic tract
because it ascends bilaterally so unilateral injury doesn't leave a deficit
54
cordotomy
destroy the spinothalamic tract. cut lateral funiculars from dentate ligament to venture rostral to highest dermotomal pain level. For patients with pain. the analgesia lasts several months
55
cerebral cortical representation of the medial lemniscus pathway
primary somatosensory cortex in postcentral gyrus
56
cerebral cortical representation of the anterolateral pathway
widespread (post central gyrus, insula, and others) reflects complex conscious awareness of pain
57
spinocerebellar tracts
information from spinal cord used by the cerebellum to coordinate movement
58
direct and indirect spinal cord information to cerebellum
direct: spinocerebellar tracts indirect: brainstem relay nuclei
59
posterior spinocerebellar tract is responsible for
proprioceptive tactile and pressure info to the legs
60
where do they posterior spinocerebellar tract fibers synapse
Clarkes nucleus
61
how do axons ascend in the posterior spinocerebellar tract
ipsilateral in the lateral funicular. forming the psct
62
how do the posterior spinocerebellar tract fivers enter the cerebellum
via the inferior cerebellar peduncle
63
how to the leg fivers in the PSCT travel
ipsilaterally and bilaterally
64
the posterior spinocerebellar tract send info for the ____ while the _____ sends info for the arms
legs, cuneocerebellar tract
65
where does the 1st order neurons of the cuneocerebellar tract synapse
at the level at which they enter. axons from lateral cuneate nucleus collect and form cuneocerebellar tract
66
where do the second order neurons of the cuneocerebellar tract synapse=
enters the inferior cerebellar peduncle to synapse int he VERMIS
67
do the cuneocerebellar tract fibers synapse in clarks's nucleus?
No
68
arm afferent fibers ascend rom ____ to the ____ in the medulla
fasciculus cuneatus to the lateral cuneate nucleus in the medulla
69
What is the anterior spinocerebellar tract (ASCT) responsible for
sending more complex information to the cerebellum
70
what two tracts carry proprioception information from the legs
anterior spinocerebellar tract and posterior spinocerebellar tract
71
how is the anterior different than the posterior spinocerebellar tract
inputs more complet. more related to attempted movement and not simple sensory signals.
72
which pathway crosses the midline twice
canterior spinocerebellar tract. ultimately fibers end ipsilateral to source
73
origin of PSCT
clarks's nucleus )t1-L2/3)
74
origin of ASCT
spinal border ells (T12-L5)
75
origin of CCT
lateral cuneate nucleus in medulla
76
major inputs of the ASCT
mechanoreceptors, movement0related interneurons
77
where are the two places the ASCT crosses the midline
in the cord and in the cerebellum
78
what peduncle do the major spincerebellar tracts use to enter the cerebellum
PSCT and CCT: inferior | ASCT: superior

Anatomy (12 decks)

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