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Flashcards in Tracts Deck (70)
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1

Each dorsal rootlet is divided into two divisions

lateral and medial division

2

lateral divison

A delta/C fibers, GSA's, enter area of white mater @ tip of dorsal horn via lissauer's tract, they then ascend or descent 1 or 2 cord segments, then enter grey mater and synapse

3

medial division

A beta/type I, II, and III; DO NOT USE LISSAUER'S TRACT, synapse in lamina III and IV, or in lower motor neuron (muscle stretch reflex: I A fiber, quick change in length of extrafusal fibers, synapse of alpha motor neuron (monosynaptic reflex)).

4

tract

organized bundle of axons (white mater)

5

ascending tracts

modulated by descending tracts by location of cell bodies**
- arousal, affective, motivation responses of stimulus
- unconscious monitoring/control of motor activity (posture/movement)

6

first order neurons

sensory neuron (A delta, A beta, type I)
- cell bodies are always in dorsal root ganglion

7

second order neurons

synapse in thalamus, neuron cell bodies in the thalamus

8

third order neurons

thalamocortical neurons

9

dorsal column/medial lemniscus (location)

dorsal column - ipsilateral fibers in dorsal white mater-cord
medial lemniscus - contralateral fibers in brain stem
cross @ tegmentum of caudal medulla

10

dorsal column/medial lemniscus (information conveyed)

vibration, joint position, 2pt touch (and light touch), pressure (association cortex)

11

association cortex

the ability to feel and recognize an object in one's hand while not looking

12

dorsal column/medial lemniscus (1st order neurons)

1st order - in DRG
- axons S5-T6 ascend via fasciculus gracilis
- axons T5 - C1 ascend in the fasciculus cuneatus

13

dorsal column/medial lemniscus (2nd order neurons)

cell bodies are in the nuclei gracile and cuneatus
- axons cross as the internal arcuate fibers and ascend as the medial lemniscus

14

dorsal column/medial lemniscus (3rd order neurons)

cell bodies are in the VPL thalamic nucleus
- axons course through the internal capsule to the sensory cortex, postcentral gyrus/post paracentral lobule (homunculus)

15

dorsal column/medial lemniscus 1st 2nd and 3rd order neurons are ________ organized

somatotopically

16

anterolateral system conveys

pain and temperature (some touch and pressure)
- A delta/C fibers

17

anterolateral system - A delta fibers

fast conducting; localized sharp/acute pain

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anterolateral system - C fiber

slow conducting; poorly localized; burning; aching pain

19

anterolateral system cross at

ventral white commissure

20

anterolateral system includes three tracts...

spinothalamic, spinoreticular, spinomesencephalic

21

ALS - spinothalamic system includes...

neospinothalamic (somatotopically organized) and paleospinothalamic

22

ALS - spinothalamic - neospinothalmic

1st order - A delta
2nd order - lamina I and V (VI-VII) and axons cross and ascend
3rd order - VPL of thalamus
conveys: sharp, well localized, discriminatory pain
terminates @ primary sensory cortex (homunculus)

23

ALS - spinothalamic - paleospinothalamic

1st order - C fibers
2nd order - lamina VII - VIII and axons cross and ascend
- collaterals go to reticular formation
3rd order - intralaminar thalamic nucleus
conveys: dull achy pain
terminates @ widespread cortex

24

ALS - spinoreticular tract conveys

- dull achy
- autonomic, behavioral, and emotional responses to the painful stimuli
- arouses cortex to maintain alertness and attentiveness (focus attention on a painful area)

25

ALS - spinoreticular tract neurons

1st - afferent from cutaneous receptors
2nd - contralateral to pontine and medullary reticular formation and ipsilateral to medullary reticular formation
3rd - thalamic nuclei, then cortex via anterior cingulate/insular cortices

26

ALS - spinomesencephalic tract conveys

reflex responses

27

ALS - spinomesencephalic tract neurons

1st - synapse in grey mater
2nd - cross in ventral white commissure, then synapse @ super colliculus for reflex response or synapse @ periaqueductal grey
- PAG: descending feedback to dorsal horn; synapse in reticular formation to modulate pain

28

ALS - spinothalamic - neospinothalamic
vs.
ALS - spinothalamic - reticular/mesencephalic/hypothalamic

neospinothalamic: seriousness of the pain (posterior partietal lobe, insula of amgdala, anterior cingulate cortex: prefrontal cortex)
reticular/mesencephalic/hypothalamic: pain is uncomfortable (brainstem nuclei, thalamus, hypothalamus)

29

anterior cingulate cortex (ACC)

function: emotional component of pain

30

ACC: amygdala

memory