6 Trigeminal Pathways - M Flashcards

1
Q

Where are the cell bodies of CN 5 afferents primary located?

A

trigeminal/semilunar ganglion

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2
Q

What are the 4 major nuclei of the trigeminal tract?

A
  1. main/primary sensory nucleus (msT)
  2. trigmeninal motor nucleus (mT)
  3. spinal nucleus
  4. mesencephalic nucleus (mes)
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3
Q

Where is the main sensory nucleus (msT) found?

A

in the mid pons enlargement lateral to trigeminal motor nucleus (mT)

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4
Q

Which trigeminal nucleus extends rostrally?

A

Mesencephalic nucleus (mes)

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5
Q

Which trigeminal nucleus extends caudally into the cervical region?

A

Spinal nucleus

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6
Q

What afferents modalities are transmitted to the cortex via the primary sensory nucleus (msT)

A

discriminative tactile & proprioceptive senstations

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7
Q

What afferent modalities are transmitted via the spinal nucleus?

A

pain & temperature

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8
Q

What afferent modalities are transmitted via the mesencephalic nucleus (mes)?

A

proprioceptive afferents from the muscles of the mastication & the TMJ

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9
Q

Identify the following structures

A
  1. mesencephalonic nucleus
  2. main sensory nucleus
  3. trigeminal ganglion
  4. spinal (trigeminal) nucleus
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10
Q

What is the primary sensory afferent of the head and face?

A

Trigeminal nerve (V1, V2, V3); review distribution

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11
Q

What are the 2 divisions of the main sensory nucleus (msT)?

A

dorsomedial & ventrolateral divisions

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12
Q

What afferents are associated with the dorsomedial division of the msT

A

afferents from oral cavity

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13
Q

What afferents are assoicated with the ventrolateral division of the main sensory nucleus?

A

V1-V3

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14
Q

2nd order afferents of the msT nucleus project to what nucleus in the thalamus?

A

VPM

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15
Q

2nd order afferents from the ventrolateral division of the msT project to ____ VPM via what tract?

A

Contralateral VPM via the anterior trigeminothalamic tract

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16
Q

2nd order neurons from the dorsolateral division of the msT project to ___ VPM via what tract?

A

ipsilateral VPM via the posterior trigeminothalamic tract/ dorsal central trigeminal tract

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17
Q

fibers of the ventrolateral msT are joined by fibers from what other nuclei in the VPM?

A

spinal trigeminal nucleus to form the trigeminothalamic lemniscus

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18
Q

Through what brainstem structure does the dorsal central trigeminal tract ascend through?

A

The periaqueductal gray matter (surrounds cerebral aqueduct in the midbrain)

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19
Q

Where are tertiary neurons of the trigeminal pathway located?

A

cell bodies in the VPM and project to the primary somatosensory cortex

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20
Q

Tertiary neurons of the VPM project via what structure to reach the post-central gyrus?

A

The posterior limb of the internal capsule

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21
Q

What part of the head receives sensory innervation from the trigeminal nerve?

A

The anterior half

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22
Q

trigeminal afferents carrying pain & temp info enter ___ nucleus and then DESCEND via what tract?

A

enter spinal nucleus and DESCEND via spinal trigeminal tract before ascending via anterior trigeminothalamic tract

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23
Q

What are the 3 regions of the spinal nucleus?

A
  1. Pars/subnucleus CAUDALIS
  2. pars/subnucleus oralis
  3. pars/subnucleus interpolaris
    4.
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24
Q

How are the afferent TO the ventrolateral msT organized?

A

V1 =posterior, V2 = middle, V3 = anterior/ventral

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25
Q

how are the afferents in the ventrolateral msT organized

A

V1 = anterior, V2 = middle, V3 = posterior

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26
Q

What is the obex?

A

narrowing of the 4th ventricle as it becomes the central canal of the spinal cord

27
Q

How are V1-V3 organized in the pars caudalis?

A

V1= most rostral, V2 = middle, V3 = most posterior

28
Q

The most rostral portions of the pars caudalis are located near what structure?

A

The obex in the medulla

29
Q

The most caudal portions of the pars caudalis are located where?

A

in the upper cervical cord (C1-C3 area)

30
Q

Does damage to the pars caudalis presents with a characteristic or non-characteristic pattern of nociceptive and thermal sensory loss?

A

Characteristic d/t little other lap between V1-V3

31
Q

Damage to the caudal portion of the subnucleus caudalis results in loss of nociceptive and thermal sensory innervation where?

A

upper portions of neck and v3-C2 dermatomes

32
Q

Damage to rostral portion of subnucleus caudalis results in nociceptive and thermal sensory loss where?

A

around mouth and nearby structures

33
Q

2nd order neurons from the spinal nucleus decussate where and join what ascending tract?

A

At the level the 1st order neurons descended to in spinal nucleus; join the anterior trigeminothalamic tract to the contralateral VPM

34
Q

Where is the pars oralis found?

A

the entrance of CN 5 in the pons –> upper medulla

35
Q

What info goes to the pars oralis?

A

tactile info from the central region of the face

36
Q

What are the boundaries of the subnucleus interpolaris?

A

upper medulla to the level of the obex (end of 4 ventricle in medulla)

37
Q

What info does the pars interpolaris get?

A

sensory info from peripheral region of face

38
Q

The pars oralis & interpolaris are heavily involved in what type of functions

A

somatic functions similar to that of the spinal cord

39
Q

What structure do afferents from the subnucleus oralis and interpolaris pass through to enter the cerebellum?

A

inferior cerebellar peduncles

40
Q

What sensory information does the mesencephalic nucleus (mes) convey?

A

unconscious proprioception & pressure from muscles of oral region

41
Q

afferents from the mes nucleus travel to what structures?

A

msT, spinal nucleus & trigeminal motor nucleus (mT)

42
Q

The mes nucleus sends afferents to what nucleus to form the jaw-jerk reflex?

A

The trigeminal motor (mT) nucleus

43
Q

The trigeminal motor (mT) nucleus send motor fibers to PA 1 via what branch of CN5

A

V3/mandibular division

44
Q

Where is the trigeminal motor nucleus found?

A

in the midpons medial to the msT nucleus

45
Q

Damage to what type of nerves would result in an increase in reflexive strength?

A

UMNs

46
Q

What muscle is involved in the jaw-jerk reflex?

A

masseter m

47
Q

afferents from which nucleus innervated the muscle spindle of the masseter m.?

A

mes nucleus

48
Q

afferent fibers of the corneal reflex terminate in what nucleus?

A

The spinal trigeminal nucleus (par caudalis)

49
Q

2nd order neurons from __ nucleus travel via __ tracts to synapse on efferents in the facial (CN7) motor nucleus

A

spinal trigeminal nucleus; trigeminothalamic tracts

50
Q

What are the 2 major trigeminocerebellar pathways

A
  1. Mesencephalic (mes) nucleus via pars interpolaris –> cerebellum
  2. Main sensory nucleus (msT) –> cerebellum
51
Q

Proprioceptive input from the jaw regarding chewing/placement travels through which nucleus befor entering the cerebellum?

A

Mesencephalic nucleus –> pars interpolaris –> cerebellum

52
Q

TMJ proprioception info enters cerebellum via what structure?

A

inferior cerebellar peduncle; (afferents from mes nucleus –> par interpolaris)

53
Q

Where in the cerebellum does the main sensory nucleus project to?

A

anterior vermis via the superior cerebellar peduncle

54
Q

What alters jaw placement/force during mastication?

A

food texture & consistency

55
Q

A unilateral lesion of the trigeminal nerve results in what?

A
  • Ipsilateral loss of sensation on anterior 1/2 of the head and motor innervation of the muscles of mastication
  • Loss of jaw-jerk & corneal blink reflexes
56
Q

Damage to what structure(s) causes alternating analgesia

A

damage to upper medulla may = damage to spinal trigeminal tract & spinal lemniscus

57
Q

How does alternating analgesia present?

A

hemianalgesia of face ipsilateral to lesion & hemianalgesia of contralateral body

58
Q

What causes alternating trigeminal hemiplegia?

A

unilateral lesion of the trigeminal nerve & corticospinal tract in the pons

59
Q

How does alternating trigeminal hemiplegia present?

A
  • ipsilateral trigeminal anesthesia and paralysis
  • contralateral spastic hemiplegia
60
Q

What is hemiplegia?

A

paralysis of 1 side of the body

61
Q

What artery supplies the anterolateral tract & spinal trigeminal nucleus/tract?

A

Posterior inferior cerebellar a. <– vertebral a.

62
Q

lesions or occlusions of PICA cause what syndrome?

A

lateral medullary (Wallenberg) syndrome

63
Q

What are the signs of lateral medullary (Wallenberg) syndrome?

A
  • contralateral hemianalgesia & hemithermoanesthesia on body
  • ipsilateral hemianalgesia & hemithermoanesthesia on face
64
Q

How would a lesion of the R trigeminal motor nucleus (mT) or trigeminal root present?

A

protrusion of the jaw to R (side of lesion)