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Neuroendocrine > Posterior Column-Medial Lemniscus pathway (PCML) & Trigem. Nuclei > Flashcards

Posterior Column-Medial Lemniscus pathway (PCML) & Trigem. Nuclei Flashcards

1
Q

What does the PCML pathway transmit?

A

Somatosensory - touch (texture, size, shape), tactile information and proprioception

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2
Q

What is proprioception?

A

Knowing where your body is in space without seeing

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3
Q

Primary afferent fibers

A

Sensory fibers

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4
Q

Where do primary afferent fibers enter the spinal cord?

A

Medial division of posterior root

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5
Q

What do the afferent fibers ascend as?

A

Posterior column

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6
Q

Posterior column - grey or white matter?

A

White

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7
Q

Afferent fibers from sacral level - T6 go where in the posterior column?

A

Fasciculus Gracilis

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8
Q

Afferent fibers from T6 - superior go where in the posterior column?

A

Fasciculus cuneatus

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9
Q

Where is the fasciculus gracilis?

A

Medial side of posterior column

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10
Q

Where is the fasciculus cuneatus?

A

Lateral side of posterior column

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11
Q

Afferent fibers from ex. T9 will go to what side of the posterior column?

A

Medial

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12
Q

Afferent fibers from ex. T3 will go to what side of the posterior column?

A

Lateral

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13
Q

What will lesions in the posterior column produce?

A

IPSILATERAL sensation loss at and below affected segment

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14
Q

What is sensory ataxia?

A

Loss of reflexes and proprioception from extremities due to lack of sensory input

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15
Q

How may a patient with sensory ataxia stand?

A

With a wide base to try and reestablish the proprioception

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16
Q

If the fibers run in the fasciculus gracilis, where will they synapse?

A

Gracile nucleus

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17
Q

If the fibers run in the fasciculus cuneatus, where will they synapse?

A

Cuneate nucleus

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18
Q

2nd order neurons from either cuneate or gracile nucleus project where?

A

Contralateral thalamus

19
Q

Where are the cuneate and gracile nuclei located?

A

Posterior Medulla

20
Q

Once the fibers synapse at either the cuneate/gracile nuclei, then what happens?

A

They cross the midline and become the medial lemniscus

21
Q

Sensory decussation

A

Crossing midline

22
Q

How do fibers cross the midline at the posterior medulla?

A

Internal arcuate fibers

23
Q

Where do the 2nd order neurons synapse?

A

Contralateral thalamus - VPL

24
Q

Where do 3rd order neurons from the VPL project?

A

Primary Somatosensory cortex

25
Q

What is the blood supply to the VPL?

A

Posterior cerebral A.

26
Q

If the posterior cerebral A. is occluded, what will be affected?

A

Contralateral sensation of the body

27
Q

What is included in the primary somatosensory cortex (S1)?

A

Postcentral gyrus and posterior paracentral gyrus

28
Q

What body parts map to the posterior paracentral gyrus?

A

Foot, LE, hip

29
Q

What artery supplies the posterior paracentral gyrus?

A

Anterior cerebral A.

30
Q

If the anterior cerebral A. is occluded, what is affected?

A

Contralateral LE sensation

31
Q

What body parts map to the postcentral gyrus?

A

Chest, UE, face, throat

32
Q

What artery supplies the postcentral gyrus?

A

Middle cerebral A.

33
Q

If the middle cerebral A. is occluded, what is affected?

A

Contralateral chest, UE, face, throat sensation

34
Q

What inputs does the secondary somatosensory cortex receive?

A

Ipsilateral primary somatosensory cortex and VPI or thalamus

35
Q

If the parietal cortical regions have lesions, what occurs?

A

Agnosia - contralateral side

36
Q

What is agnosia?

A

Limb not recognized as part of patients own body but sensation is not super affected

37
Q

What are the 4 trigeminal nuclei?

A

Mesencephalic, principal sensory nucleus, spinal nucleus and trigeminal motor nucleus

38
Q

What afferent signals does the mesencephalic nucleus transmit?

A

Proprioception from TMJ, muscles of mastication and extraocular muscles

39
Q

What does the principal sensory nucleus transmit?

A

Touch and pressure

40
Q

Describe the orientation of the principal sensory nucleus

A

Face is oriented upside down - anteriorly = V1 and posteriorly = V3

41
Q

Anterior trigeminothalamic tracts project to which VPM of thalamus?

A

Contralateral

42
Q

Posterior trigeminothalamic tracts project to which VPM of thalamus?

A

Ipsilateral

43
Q

Which nucleus is the only one that has pseudopolar neurons?

A

Mesencephalic

44
Q

Describe the jaw jerk reflex

A

Stretch massater muscle down, axon synapses at trigeminal motor nuclues, and then both massaters contract
– testing trigeminal motor nucleus and V3

Neuroendocrine (47 decks)

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