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Flashcards in Ascending Sensory Systems Deck (40)
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1
Q

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

A

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

2
Q

what do somatosensory receptors detect ?

A

mechanical, chemical, and thermal changes

3
Q

somatosensory neurons are composed of what type of neurons

A

pseudounipolar

4
Q

what type of receptors would you find in hairy skin ?

A
  • Merkel nerve ending cells
5
Q

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

A
  • Meissner corpuscles
  • Merkel cells
  • Pacinian corpuscles
  • ruffini ending
6
Q

what do meissner corpuscles sense ? where ?

A
discriminative touch (2 point touch) 
-fingertips
7
Q

what do merkel nerve ending cells sense ?

A

discrimintative (2 point) touch, fine touch

8
Q

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

A

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

9
Q

what do pacinian corpuscles detect ? where ?

A

vibration, fingers and palm

10
Q

what do free nerve endings sense/detect ?

A

pain, crude touch, temperature

11
Q

what role does myelination have on free nerve endings

A

Myelinated - elicits sharp prick phase of pain

Unmyelinated - elicits slow/aching pain

12
Q

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

A

Anterior funiculi, lateral funiculi, posterior funiculi

13
Q

whare at anatomically are descending tract pathways located in the brain

A

anterior funiculi, lateral funiculi

14
Q

what is another name synonymous with posterior column

A

medial lemniscus system

15
Q

what does the medial lemniscus system convey to the brain

A

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

16
Q

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 ?

A

Medial - large, heavily myelinated fibers

Lateral - small/finely myelinated or unmyelinated fibers

17
Q

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

A

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

18
Q

once ascending fibers reach the brainstem, where do they synapse

A

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

19
Q

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

A

second order fibers cross in the caudal medulla

20
Q

where is the primary somatosensory cortex ?

A

postcentral gyrus of parietal lobe

21
Q

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

A

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

22
Q

what is ataxia

A

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

23
Q

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

A

loss of proprioception and tactile discrimination

24
Q

what is another name for the anterolateral pathway

A

spinothalamic tract

25
Q

what does the spinothalamic tract detect/convey

A

pain and temperature

26
Q

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

A

ventral posterolateral nucleus of the thalamus

27
Q

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

A

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
Q

damage to the anterolateral pathway would cause ?

A

loss of pain and temperature sensations

-also loss of itch and tickle sensations

29
Q

what Brodmann Areas comprise the primary somatosensory cortex

A

3,1,2

30
Q

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

A

primary motor - 4

premotor - 6

31
Q

what is a cordotomy, and how is it used today

A

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
Q

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

A

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

33
Q

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

A

brainstem relay nuclei

34
Q

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

A

True

35
Q

what type of information does the posterior spinocerebellar tract convey ?

A

conveys ipsilateral leg proprioception

36
Q

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

A

Clarke’s nucleus

37
Q

how far caudal does Clarke’s nucleus extend ?

A

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

38
Q

what does the cuneocerebellar tract convey ?

A

ipsilateral arm proprioception

39
Q

what does the anterior spinocerebellar tract convey ?

A

more complex ipsilateral leg information

40
Q

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 ?

A

anterior spinocerebellar tract