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Neuro Exam 2 > 10. Somatosensory: Nociception, Thermal Sense & Touch > Flashcards

10. Somatosensory: Nociception, Thermal Sense & Touch Flashcards

1
Q

what is the purpose of the anterolateal system (ALS)

A

somatosensory system to notify us about tissue damage

-nociception, thermal sensation, nondiscriminative touch, itching to body

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2
Q

what is the basic path for direct ALS pathway

A

sp cord –> lateral thalamus –> somatosensory cortices

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3
Q

what is the basic path for indirect ALS pathway

A

sp. cord –> reticular formation –> medial thalamus –> cingulate, frontal & limbic cortices

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4
Q

what fibers make up the ALS

A

spino—

  1. —thalamic (direct path)
  2. —mesencephalic
  3. —reticular (indirect path)
  4. —bulbar
  5. —hypothalamic
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5
Q

what is the basic path of the spinothalamic fibers

A

spine –> thalamus (VPL & VPI nuclei)

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6
Q

what is the basic path for spinomesencephalic fibers

A

spine –> reticular formation & periaqueductal gray

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7
Q

what is the basic path of the spinobulbar fibers

A

spine –> various nuclei of brain

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8
Q

what is the basic path of spinohypthalamic fibers

A

spine —> hypothalamus & other nuclei

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9
Q

what is the basic path of the spinoreticular fibers

A

spine –> medulla, pons, midbrain (reticular formation)

=indirect path

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10
Q

what are characteristics of free nerve endings

A

found all over the body

density varies on body part: more receptors in hands, face

=generic

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11
Q

where do free nerve ending fibers enter the spinal cord

A

lateral division of post root entry zone

–> stay, ascend, descend 2ish segments at laminae 1, 2, 5

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12
Q

where do free nerve ending fibers fo after they enter the spinal cord

A

move w/i post.lat. fasciculus (Lissauer Tract)

-ascend/descend after bifurcating

or stay in same level and end on interneuron to stimulate reflex

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13
Q

what are the steps of the direct spinothalamic pathways

A

nondiscrim tactile, thermal, nociceptive signal –>

enter lat root entry –>

enter post.lat. fasciculus & bifurcate –>

ascending/descending branches end on 2nd order neuron on post horn –>

cross midline via ant commissure –>

move up in contralateral ALS (few ipsi)–>

end on VPL/VPI of thamalus (3rd order)

–> 3rd order neuron to S1

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14
Q

how is the indirect path different than the direct path

A

terminate on the reticular formation, instead of going up to cortex

-some to VPM and then cortices

=indirect, general feedback from body ==> makes you aware of signal

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15
Q

what are the steps of the indirect spinothalamic pathway

A

fibers into post horn - ascend/descend & synapse at laminae 2 and 3

–> send axons cross and join the contralat ALS

–> project to reticular formation

–> 3rd order neurons project to intalaminar nuclei & post group nuclei

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16
Q

what is the ALS somatotopic organization

A

sacral/coccyx - post.lat

most rostral are added in ant.medially (lower cervical & Upper cervical)

17
Q

what happens when you hace a tumor compresing the cord from lateral to medial at the ALS region

A

affect lumbar/sacral regions first

18
Q

what happens if you have an intermedullary tumor damaging the cord from medial to lateral at the ALS region

A

affect upper cervical first

19
Q

what is the path for facial sensation

A

direct/indirect via trigeminal N

primary afferent from trigeminal ganglion –>

attach to sensory/motor roots at ventrolat. pons –>

project down in spinal trigeminal tract to C3 –>

join Lissauer’s (post.lat) tract

–> target VPM

–> 3rd order to part of homunculus that represents face

20
Q

what is the basic path of the anterior trigminothalamic pathway

A

face –> spinal cord to 2nd order axon from causal nucleus

–> up as anteriro trigeminothalamic tract

–> contralat VPM

–> posterior limb of internal capsule

–> somatosensory (& limbic cortices)

21
Q

what is the BS to trigeminal structures in the medulla

A

PICA

Post. spinal A

22
Q

what is the anatomical orientation of the face on the spinal trigeminal nucleus

A

inverterd

V1 inferior & V3 superior

23
Q

what is the pars caudalis

A

most caudal part of spinal trigeminal nucleus

from C2/C3 to Obex

-somatotopic head to toe representation –> circumoral/intraoral fibers terminate near obex

–> caudal/lateral fibers terminate in caudal regions of cerival cord

24
Q

what is pars oralis

A

spinal trigreminal nucleus part that extends from pons to superior medulla

-tactile info from central face

25
Q

what is the pars interpolaris

A

spinal trigeminal nucleus part that goes from superior medulla to obex

  • get info from peripheral face
  • projects to cerebellum via inf cerebellar peduncle
  • relay tactile info to contralat VPM
26
Q

explain “onion-peel sensory loss”

A

caudal leasion –> large area around mouth spared from sensory loss

rostral region –> sensory loss stars at back of head & converges at eyes

*rmr trigeminal fibers overlap spinal fibers of adjacent areas of skin*

27
Q

what is the trigemino-reticulo-thalamic-path

A

pain fibers - bilateral to reticular formation(RF) as terigeminoreticular fibers

-input fasciliate ascending reticular activating system (in aroudal & alertnes)

*RF responsible for regulating wakefulness & sleep-wake transition*

28
Q

what occurs if sulcal branches of ant. spinal A are occluded

A

patchy loss of nociceptive, thermal & touch over contralateral side (about 2 segments below lesion)

29
Q

what occurs in an ant.lat cordotomy

A

complete loss of nociceptive, thermal and touch

30
Q

What happens with hemisection of sp. cord (Brown-sequad)?

A

contralat: loss of nociceptive & thermal sensation over body (start 2 segments below lesion)
ipsi: loss of discriminative tactile, vibtation and proprioception over the body at and below lesion –> could have motor loss/paralysis depending on level
- affecting both ALS and post column

31
Q

what is syringomyelia

A

cystic cavitation of central regions of spinal grey matter

-impinge ant comminssure (contains both sided ALS fibers that cross)

if at C4-C5 -> bilateral loss of nondiscriminative tactile nociception and thermal (several segments below)

“Cape-like” loss = over shoulders and down to nipple level

32
Q

what happens in herpes zosters infxn

A

viral, dermatomal distribution

latent in NS –> reactivate with stress & travel to that dermatome –> skin irritation, loss of sensibilty & postherpetic neuralgia (severe pain(=)

33
Q

what is medullary syndrome ?

what if lesion medial medulla?

A

vascular lesion/tumor br.st affect discriminative touch & nociceptin differently

lesion medial medulla —> contralat loss of discriminative touch & vibration (but pain and thermal intact)

34
Q

what occurs in lateral medullary (wallenburg) syndrome

A

vascular lesion to PICA -

contralat loss of pain and temp over body (ALS)

& ipsilat loss of pain/temp over face (spinal trigeminal tract)

PICA supplies ALS and spinal trigeminal nucleus/tract

35
Q

what occurs in an unliteral lesion of the trigeminal N

A
  • Anesthesia and loss of general sensations in the trigeminal dermatomes

– Loss of jaw-jerk reflex

– Atrophy of the muscles of mastication

– Loss of ipsilateral and consensual corneal reflex

36
Q

what is alternating analgesia of the trigeminal n

A

Br.st lesions in upper medulla may destroy primary fibers in spinal

trigeminal tract (descending tract of V), & secondary fibers in spinal lemniscus

= ipsilateral hemianalgesia of the face & contralateral hemianalgesia of the body

37
Q

what is alternating trigeminal hemiplegia

A

Unilat destruction of the trigeminal nerve & CST in the pons

– Ipsilateral trigeminal anesthesia & paralysis, & contralateral spastic hemiplegia

38
Q

what are the primary defects in lesions of trigeminal N or its central nuclei

A

Ipsilateral loss of pain, thermal, and tactile sensations of face & scalp

– Ipsilateral loss of the same sensations in the oral cavity & teeth

– Ipsilateral paralysis of masticatory muscles

-possible ipsilat loss of afferent limb of corneal reflex (but still get blinking on both sides bc contralat side intact)

Neuro Exam 2 (23 decks)

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