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BMB G Lab Underline Terms > Lab 6: Somatosensory Systems II > Flashcards

Lab 6: Somatosensory Systems II Flashcards

1
Q

Marginal Zone

A

Thin rim of cells dorsal to the size able substantia gelatinosa

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2
Q

Substantia Gelatinosa

A

(Rexed’s lamina II)

Receives terminations of first order pain and temperature neurons

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3
Q

Ventral (anterior) White Commissure

A

Crossing of the axons from pain/temperature projection neurons to reach the lateral funiculus of the opposite side

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4
Q

Anterolateral System

A

Consists of the crossed pain/temperature fibers that ascend to the brain stem and thalamus on the opposite (contralateral to) the stimulated receptors.

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5
Q

Reticular Formation

A

Receives some fibers of the ALS that take a multisynaptic course to terminate in the intralaminar nuclei of the thalamus (slow pain pathway)

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6
Q

Raphe Nuclei

A

Pale nuclei near that midline that:

  • receive descending fibers from the periaqueductal gray of the midbrain
  • project fibers to the dorsal horn of the spinal cord for inhibition of ascending pain transmission
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7
Q

Dissociated Sensory Loss

A

-a small stroke in the medulla can affect one sensory system but not the other
-the ALS is in the posterolateral vascular territory (ventrolateral tegmentum) and the medial lemniscus is in the paramedian zone (close to the midline)
This occurs in Wallenberg (lateral medullary) Syndrome which results from an infarct in the vascular territory of PICA

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8
Q

Caudal Pons

A

The Medial Lemniscus has begun to move laterally towards the ALS

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9
Q

Rostral Pons

A

The medial lemniscus meets the ALS in the lateral tegmentum at this level and they travel adjacent to each other en route to the thalamus

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10
Q

Periaqueductal Gray Nuclei of the Midbrain

A
  • receive fibers from ALS

- send descending fibers to raphe nuclei of brainstem for inhibition of pain transmission

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11
Q

Ventral Posterolateral (VPL) Nucleus of the Thalamus

A

Synapse site of fibers of the ALS

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12
Q

Posterior limb of internal capsule

A

Path of fibers from the VPL to the somatosensory cortex

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13
Q

Internal Medullary Lamina

A

Sheet of fibers in thalamus

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14
Q

Intralaminar nuclei

A

Nuclei in internal medullary lamina that:

  • receive pain/temperature fibers from the reticular formation
  • send axons to widespread areas of cortex
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15
Q

Posterior Limb, internal capsule

A

Contains fibers (thalamic radiations) from the VPLs to the somatosensory cortex (postcentral gyrus and posterior paracentral gyrus, Brodmann Areas 3,1,2)

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16
Q

Postcentral Gyrus and Posterior part of Paracentral Lobule

A

Where sensations of discriminative touch/pressure (medial lemniscus) and pain/temperature (ALS) are detected

17
Q

Posterior Parietal Cortex

A

Where sensations are recognized

18
Q

Ophthalmic and maxillary divisions of Trigeminal Nerve

A
  • course in the wall of the cavernous sinus

- contain sensory fibers only

19
Q

Mandibular Division of Trigeminal Nerve

A

-contains sensory and motor fibers

20
Q

Trigeminal Ganglion

A

Consists of cell bodies of sensory fibers from face, ear, orbit, oral cavity, nasal cavity, paranasal sinuses meninges

21
Q

Trigeminal Nerve Roots

A

Located in the lateral tegmentum, between the motor and main sensory nucleus of V

22
Q

Motor Nucleus (V)

A

Medial to the trigeminal nerve roots; supplies the muscles of mastication

23
Q

Main Sensory Nucleus (V)

A

Lateral to the trigeminal nerve roots

24
Q

Properties of Main Sensory Nucleus (V)

A
  • receive axons from large-fiber neurons of trigeminal ganglion
  • are comparable to dorsal column nuclei in that they’re involved in discriminative touch
  • send axons across the midline (decussation not visible) to joint the ventral trigeminothalamic tract
25
Q

Mid Pons

A

Main sensory and motor nuclei of the trigeminal nerve (V): in the dorsolateral tegmentum of the pons
Trigeminal nerve roots: easy to see between the main sensory and motor nuclei in the slice on the left

26
Q

Spinal Trigeminal Tract

A

The pain/temperature neurons in the trigeminal ganglion from the anterior head have central processes that enter the pons and descend into the medulla and rostral spinal cord

27
Q

Caudal Medulla

A

Spinal Trigeminal Tract: central processes of neurons for pain/temperature from the ipsilateral face and teeth
Spinal Trigeminal Nucleus: medial to the spinal trigeminal tract; receives fibers from the spinal Trigeminal tract; contains neurons that process pain and temperature information from the face and send axons across the midline to become the VENTRAL TRIGEMINOTHALAMIC TRACT (VTTT)

28
Q

Spinal Trigeminal Nucleus and Substantia Gelatinosa

A

The spinal trigeminal nucleus is continuous caudally with the substantia gelatinosa of the dorsal horn of the spinal cord. Neither of these structures are visible in a clinical scan, but the general position can be determined because both are located in the lateral tegmentum, with the tract being peripheral to the nucleus

29
Q

Mid/Rostral Medulla

A

Spinal Trigeminal tract: lateral to spinal trigeminal nucleus
Spinal trigeminal nucleus: has cells whose axons cross (crossing not visible) and ascend as the ventral trigeminothalamic tract to the thalamus

30
Q

VTTT Fiber Organization

A

They’re not gathered into a discrete bundle in the medulla, but in the caudal Pons they are found dorsal to the medial Lemniscus

31
Q

Mid Pons (trigeminal nerve system locations)

A

Ventral Trigeminothalamic Tract (VTTT):
-has fibers from the contralateral spinal Nucleus of V plus some from the contralateral main sensory nucleus of V
-travels dorsal to the medial lemniscus
-projects to the ventral posterior medial (VPM) nucleus of the thalamus
Main sensory nucleus of V:
Receives input from discriminative touch and vibration receptors via fibers of the trigeminal nerve
Motor Nucleus of V: BE motor nucleus to the muscles of mastication
Trigeminal Nerve Roots: pass between the main sensory and motor nuclei of V

32
Q

Midbrain

A

VTTT: dorsal to the medial lemniscus: carries sensory information from contralateral face
Medial Lemniscus: carries discriminative touch sensation from the contralateral trunk and limbs
ALS: carriers pain and temperature sensation from the contralateral trunk and limbs

33
Q

Ventral Posterior Medial (VPM) Nucleus of the Thalamus

A
  • synapse for fibers of the VTTT
  • located medial to the VPL nucleus
  • is a sensory relay nucleus of the thalamus for general sensations from the face and for taste
34
Q

Posterior Limb of Internal Capsule

A

Lateral to the thalamus; has fibers from the VPM and VPL en route to the postcentral gyrus and posterior paracentral gyrus

BMB G Lab Underline Terms (15 decks)

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