Ascending Sensory Systems Flashcards Preview

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Flashcards in Ascending Sensory Systems Deck (40):
1

what are the 3 mechanisms that keep cerebral blood flow constant under regional changes

1 - autoregulation (vasodilation/vasoconstriction)
2 - collaboration and response to brain activity
3 - cerebral vascular autonomics

2

what do somatosensory receptors detect ?

mechanical, chemical, and thermal changes

3

somatosensory neurons are composed of what type of neurons

pseudounipolar

4

what type of receptors would you find in hairy skin ?

- Merkel nerve ending cells

5

what type of receptors would you find in glabrous (hairless) skin ?

-Meissner corpuscles
-Merkel cells
-Pacinian corpuscles
-ruffini ending

6

what do meissner corpuscles sense ? where ?

discriminative touch (2 point touch)
-fingertips

7

what do merkel nerve ending cells sense ?

discrimintative (2 point) touch, fine touch

8

what is spacial resolution, and what part of arm has the best ?

the number of cutaneous receptors, fingers have the best cuz more Merkel nerve endings and meissner corpuscles in fingers than palm

9

what do pacinian corpuscles detect ? where ?

vibration, fingers and palm

10

what do free nerve endings sense/detect ?

pain, crude touch, temperature

11

what role does myelination have on free nerve endings

Myelinated - elicits sharp prick phase of pain
Unmyelinated - elicits slow/aching pain

12

where at anatomically are ascending tract pathways generally found in the brian

Anterior funiculi, lateral funiculi, posterior funiculi

13

whare at anatomically are descending tract pathways located in the brain

anterior funiculi, lateral funiculi

14

what is another name synonymous with posterior column

medial lemniscus system

15

what does the medial lemniscus system convey to the brain

conveys touch, pressure, vibration, and where limbs are positioned in space

16

as the spinal afferent fibers enter their ipsilateral dorsal root ganglion, then continue as rootlets to enter the spinal cord the fibers divide into 2 divisions, what are they ?

Medial - large, heavily myelinated fibers
Lateral - small/finely myelinated or unmyelinated fibers

17

T/F once fibers are ascending the spinal cord w/sensory input, there can be NO additional input into the posterior collumn laterally ?

False, fibers continue to add to the existing ones laterally untill reach the brainstem

18

once ascending fibers reach the brainstem, where do they synapse

synapse in the nucleus gracilis and nucleus cuneatus (posterior collumn nuclei)

19

what order of fibers cross the midline ? where do the cross at in the medial lemniscus system

second order fibers cross in the caudal medulla

20

where is the primary somatosensory cortex ?

postcentral gyrus of parietal lobe

21

what do the third order fibers in the medial lemniscus system do ?

originate in thalamus and synapse in primary somatosensory cortex (postcentral gyrus)

22

what is ataxia

uncoordinated movements as brain cant direct motor activity w/o sensory feed back, result of posterior collumn injury

23

what would happen if there was an injury to the posterior collumn

loss of proprioception and tactile discrimination

24

what is another name for the anterolateral pathway

spinothalamic tract

25

what does the spinothalamic tract detect/convey

pain and temperature

26

where does the spinothalamic tract ultimately convey the sensory information of pain and temperature in the brain

ventral posterolateral nucleus of the thalamus

27

what does in mean saying that the spinothalamic tract crosses the midline with rostral inclination ?

it means that the input can climb 1 or 2 spinal levels before it crosses and synapses forming the anterolateral pathway. So pain from T12 would be felt in T10 or T11

28

damage to the anterolateral pathway would cause ?

loss of pain and temperature sensations
-also loss of itch and tickle sensations

29

what Brodmann Areas comprise the primary somatosensory cortex

3,1,2

30

what Brodmann Ares comprise the primary motor cortex,l pre motor cortex ?

primary motor - 4
premotor - 6

31

what is a cordotomy, and how is it used today

it is the destruction/cutting of the spinothalamic tract (anterolateral pathway) in order to alleviate patients with never ending pain
-not used today much cuz pain comes back eventually

32

what are the 3 direct tracts that relay spinal cord information to the cerebellum

1 - posterior spinocerebellar tract
2 - cunocerebellar tract
3 - anterior spinocerebellar tract

33

what is the indirect way to relay spinal cord information to the cerebellum

brainstem relay nuclei

34

T/F humans have absolutely NO conscious awareness that there are tracts relaying information from spinal cord to cerebellum ot coordinate movement ?

True

35

what type of information does the posterior spinocerebellar tract convey ?

conveys ipsilateral leg proprioception

36

the posterior spinocerebellar tract is made of axon from cell bodies found where ? this is also where information synapses

Clarke's nucleus

37

how far caudal does Clarke's nucleus extend ?

L2 , does not exist caudal to L2 so all leg info will come and synapse at L2 in Clarke's nucleus

38

what does the cuneocerebellar tract convey ?

ipsilateral arm proprioception

39

what does the anterior spinocerebellar tract convey ?

more complex ipsilateral leg information

40

which of the 3 tracts relaying information from the spinal cord to the cerebellum to coordinate moovement conveys information ipsilaterally because it crosses teh midline twice ?

anterior spinocerebellar tract