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Neuroendocrine Exam 2 > Somatosensory Tracts 1 > Flashcards

Somatosensory Tracts 1 Flashcards

1
Q

What is the DCML pathway used for?

A

general sensation and proprioception

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2
Q

What is the ability to discriminate between two stimuli simultaneously?

A

two-point discrimination

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3
Q

what is the area of skin that is innervated by somatic afferent fibers?

A

receptive field

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4
Q

small receptive fields have what type of receptor density?

A

high

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5
Q

large receptive fields have what type of receptor density?

A

low

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6
Q

where are the cell bodies located for primary afferent fibers?

A

in the dorsal root ganglion

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7
Q

how do the primary afferent fibers enter the spinal cord?

A

via the medial division of the posterior root

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8
Q

what are the two posterior columns?

A

the fasciculus gracilis and the fasciculus cuneatus

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9
Q

The fasciculus gracilis is responsible for what region of the body?

A

sacral–> T6 region

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10
Q

the fasciculus cuneatus is responsible for what region of the body?

A

T6–> superior

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11
Q

sacral level fibers in the posterior column are positioned how?

A

medially

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12
Q

fibers from progressively more rostral levels are added to the posterior column how?

A

laterally

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13
Q

Lesions of the fasciculus gracilis or fasciculus cuneatus? spinal cord lesions result in what?

A

ipsilateral reduction or loss of discriminative, positional, and vibratory tactile sensations AT AND BELOW the segmental level of injury

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14
Q

what is sensory ataxia?

A

loss of muscle stretch (tendon) reflexes and proprioceptive losses from the extremities due to lack of sensory input

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15
Q

where are the gracile nucleus and cuneate nucleus found?

A

in the posterior medulla

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16
Q

what do the gracile nucleus and cuneate nucleus contain?

A

2nd order neurons on the DCMLS

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17
Q

once the second order neurons receive input from the primary afferents (1st order neurons), what happens next?

A

they send their axons to the contralateral thalamus

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18
Q

what is the name of the location of where the crossing over takes place?

A

internal arcuate fibers

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19
Q

once the sensory decussation occurs, what do the fibers ascend as?

A

the medial lemniscus (ML)

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20
Q

where does the medial lemniscus terminate?

A

in the ventral posterolateral nucleus (VPL) of the thalamus

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21
Q

what is housed in the VPL of the thalamus?

A

3rd order neurons that project to the cortex

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22
Q

if we have damage in the medulla or other portions in the brainstem, what will the deficits look like?

A

they will be on the contralateral side

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23
Q

Before reaching the VPL of the thalamus, what happens to the ML?

A

it rotates

24
Q

what is the blood supply of the thalamus nuclei?

A

thalamogeniculate branches of the posterior cerebral artery

25
Q

what would a lesion of the thalamogeniculate branches of the posterior cerebral artery result in?

A

loss of all tactile sensation over the contralateral body and head

26
Q

What happens after the 3rd order neurons in the thalamus receive input from the 2nd order neurons?

A

they traverse the posterior limb of the internal capsule to get to the cortex

27
Q

where specifically on the cortex do the third order neurons go?

A

the primary and secondary somatosensory cortices

28
Q

Where is the primary sensory cortex located?

A

in the parietal lobe

29
Q

what makes up the primary sensory cortex?

A

the postcentral gyrus and the posterior paracentral gyrus

30
Q

what is the blood supply of the SI cortical areas?

A

anterior and middle cerebral arteries (ACA and MCA)

31
Q

what would a MCA lesion produce?

A

tactile loss over the contralateral upper body and face

32
Q

what would an ACA lesion produce?

A

tactile loss over the contralateral lower limb

33
Q

where is the secondary somatosensory cortex located?

A

inner face of the upper bank of the lateral sulcus

34
Q

where does the secondary somatosensory cortex get its input from?

A

inputs from the ipsilateral SI cortex and ventral posterior inferior nucleus (VPI) of the thalamus

35
Q

besides the primary and secondary somatosensory cortices, where else can also receive tactile inputs?

A

parietal cortical regions

36
Q

what would a lesion in the parietal association area produce?

A

agnosia- the contralateral body region(s) are lost from the body map- limb is not recognized as part of the patient’s own body- sensation is not radically altered

37
Q

where do the primary afferents of the face come from?

A

the trigeminal ganglion

38
Q

how many trigeminal nuclei are there?

A

4

39
Q

where is the mesencephalic nucleus of the trigeminal nuclei located?

A

midbrain

40
Q

where is the principal sensory nucleus of the trigeminal nucleus found?

A

the midpons

41
Q

what is the role of the principal sensory nucleus of the trigeminal nucleus?

A

discriminative touch and pressure

42
Q

where is the spinal nucleus of the trigeminal nucleus found?

A

obex of the spinal cord–> C2/C3

43
Q

what is the role of the spinal nucleus of the trigmeinal nucleus?

A

temperature and non-discriminative touch

44
Q

where do the primary afferents of the face target their axons?

A

they target 2nd order neurons in the principal sensory nucleus

45
Q

where are the V1 (opthalmic) fibers located in the principal sensory nucleus?

A

anterior

46
Q

where are the V2 (maxillary) fibers located in the principal sensory nucleus?

A

in between the V1 fibers and the V3 fibers

47
Q

where are the V3 (mandibular) fibers located in the principal sensory nucleus?

A

posterior

48
Q

Once the 2nd order neurons receive input from the primary afferent neurons of the face, we have two options. what are those two options?

A

the anterior trigeminothalamic tract or the posterior trigeminothalamic tract

49
Q

If you have the anterior trigeminothalamic tract, what happens to the 2nd order neurons?

A

they cross the midline and then ascend on the contralateral side to the contralateral VPM in the thalamus

50
Q

if you have the posterior trigeminothalamic tract, what happens to the 2nd order neurons?

A

they stay ipsilateral, ascend, and target the ipsilateral VPM nucleus in the thalamus

51
Q

the posterior trigeminothalamic tract is specific to what?

A

the oral cavity

52
Q

where do the third order neurons from the VPM project?

A

via the posterior limb of the internal capsule, project to the primary somatosensory cortex

53
Q

what type of neurons make up the mesencephalic nucleus?

A

pseudounipolar neurons

54
Q

why would you use the jaw-jerk reflex?

A

if you suspect upper motor neuron damage

55
Q

what is the mesencephalic nucleus responsible for?

A

regulating the oral cavity/ proprioception of the face-specifically the jaw, tongue and lips

56
Q

what nucleus is in charge of the specific way we chew food?

A

the mesencephalic nucleus

57
Q

what is the blood supply of the primary sensory nucleus of the trigeminal nucleus?

A

long circumferential branches of the basilar artery and branches of the anterior inferior cerebellar artery as well as a smidge of the superior cerebellar artery

Neuroendocrine Exam 2 (17 decks)

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