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Neuro Final > Pons 3 (CN 5) > Flashcards

Pons 3 (CN 5) Flashcards

1
Q

what CN is found in the middle of the pons? how does it exit/enter?

A

CN5

laterally

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2
Q

does every brainstem level have a trigeminal nucleus?

A

yes, trigeminal nuclei at all levels of the brainstem

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3
Q

where is the medial lemniscus inside in the mid pons?

A

inside the tegmentum

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4
Q

what kind of sensory info does the ventral trigeminothalamic tract contain?
-where will it synapse?

A

2nd order crossed sensory info (from the opposite face)

-will synapse/terminate in the VPM thalamus

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5
Q

what kind of info does the dorsal trigeminothalamic tract contain? from what face?

  • where will it synapse?
  • what is it a constituent of
A

2nd order uncrossed sensroy info

  • from the ipsi face
  • will synapse/terminate in the VPM thalamus
  • one constituent of the “trigeminal lemniscus”
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6
Q

where in the brainstem section can you see both the motor nucleus of V and the principal sensory nucleus of V

A

mid pons
level of CN 5
-motor nucleus is medial to the chief sensory nucleus of V

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7
Q

CN5 is threaded btwn the motor nucleus of V and the principal sensory nucleus of V

  • where is the sensory info headed?
  • where did the motor info orginiate and wehre is it headed?
A
  • snsory headed towards principal nucleus

- motor info orginate from motor nucleus of V and is headed towards the muscles of mastication

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8
Q

CN 5 travels through the _____ and emerges wehre?

A

MCP

emerges out the lateral aspects of the midpons

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9
Q

a lesion in the midpons damaging the ML and STT (together now) would do what?

A

affect the general somatic sensations from the contralateral body

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10
Q

what do the fibers of CN 5 for the GSA mediate? what do the SVE innervate?

A

GSA: mediate general sensation from the face, eye, nasal, and oral cavities
SVE: innervates muscles of mastication (smaller motor component)

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11
Q

which division of the trigeminal nerve has motor fibers as well as general sensory fibers?

A

V3-mandibular division

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12
Q

where are V1, V2, and V3 located

A

V1 and V2 in the wall of the cavernous sinus

V3 is not in the cavernus sinus

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13
Q

where are motor commands coming from (at the mid pons level) and what will they head through

A

coming from the motor nucleus of V and will be heading through V3 to the muscles of mastication

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14
Q

how is sensory info coming in and into what?

A

sensory info is coming in via V1, V2, and V3 into the brainstem
-some info will be diving down to the medulla (spinal nucleus and tract of V) whereas other info will be heading to the principal sensory nucleus of V

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15
Q

will the motor nucleus of V receive corticobulbars (UMNs)?

A

yes

  • it is motor to striated skeletal msucle, it is a LMN
  • receives bilateral corticobulbars
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16
Q

where can the sensory afferents of CN5 synpase on

A

spinal trigeminal nuclues, chief snesory nucleus or the mesencephalic nucleus

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17
Q

what are the CNs that send sensory afferents to the spinal trigeminal nucleus

A

7, 9, 10-all convey sensory info from the skin around the ear to the spinal nucleus of V

5-conveys info from the face/head/orbit/dura from each of its 3 divisions (V1, V2, V3) to this same nucleus

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18
Q

where does the chief nucleus of V gets its sensory info from?

A

CN 5

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19
Q

what is the mesncephalic nucleus of V involed w/ ?

what things are invovled w/ this

A

proprioception

  • TM joint
  • muscles of mastication
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20
Q

where is the spinal trigeminal nucleus in mid pons?

A

gone, the kissing nuclei of V replace

21
Q

what are the 4 trigeminal nuclei

A

spinal trigeminal nucleus
chief sensory nucleus of V
mesencephalic nucleus
motor nucleus of V

22
Q

where do the peripheral processes bring in sensory info from?
what kind of snesory info do they contain

A

from the periphery via V1, V2, and V3

  • info about pain, temp, and touch
  • contains all 3 types of sensory fibers (pain, temp,touch)
23
Q

the cells of the trigeminal ganglion send out “central prcoesses” to what

A

to the brainstem via CN5

  • sensory afferents want to find a snesory trigeminal nucleus to synapse upon
  • CN 5 enters the brainstem at the mid pons level
24
Q

wehre do pain and temperature fibers synapse on in the 1st order trigeminalothalamic tract (periphery to CNS nucleus)

A

dive down to synapse on the caudal spinal trigeminal nucleus, located in the lateral medulla

25
Q

what happens to light touch info on the 1st order trigeminalothalamic tract (peripher to CNS nucleus)

A

light touch bifucates, some goes to the rostral spinal trigeminal nucleus; some goes to the cheif sensory nucleus

26
Q

what happens to 2 pt tactile in the 1st order trigeminothalamic tracts

A

goes exclusively to the cheif sensory nucleus

27
Q

is there any 2 point tactile info in the medulla?

A

no

28
Q

what do the 2nd order axons in the trigeminothalaitc tract synapse

A

thalamus

29
Q

where does the ventral trigeminothalamic tract start

  • where does it cross and what does it rise to synapse on
  • what is it anatomically associated w/
  • what kind of info does it convey
A

starts in the spinal trigeminal nucleus as well as in the principal sensory nucleus

  • crosses the midline and rises to synapse on VPM thalamus
  • anatomicall asso w/ the medial lemniscus
  • conveys info about 3 types of general sneosry modalities NOT proprioception though
30
Q

if you have a pt w/ unilateral loss of tactile facial sensation, the lesion is problaby…..

A

peripheral -1st order

31
Q

where do 3rd order axons do?

where will they synapse

A

travel through the post limb of the internal capsule to finally synapse in the “face” area of the somatosensory cortex in the parietal lobe (post central gyrus)

  • uncrossed
  • PLIC to cortex basically…
32
Q

where does medial lemniscus convey info from

where does trigeminal lemniscus convey info from

A

body

head/face

33
Q

where does light touch info from the cornea head down to synapse in

A

the rostral spinal trigeminal nucleus

34
Q

why does light touch info bifurcate?

A

sends corneal light touch down to the spinal trigeminal nucleus but allows other light touch info to go to the cheif sensory nucleus
-light touch info from the cornea can be close to the motor nuclei of VII…in the low PONS for corneal reflex

35
Q
  • why do corneal reflex afferents not ascned to VPM thalamus?
  • where do they terminate
  • what are their 2nd order neurons and wehre are they headed
  • what are their 3rd order neurons and what do they innervate
A

bc it is a “reflex” and so doesn’t get the cortex involved

  • terminate on the rostral spinal nucleus of V
  • 2nd order neurons were internerons heading to the both motor nuclei of VII
  • 3rd order neuron are the CN 7 LMNs that go out to innervate both orbicular oculi muscles to help you blink
36
Q

in the corneal reflex, wehre are the interneurons sent out to synpase

A

both motor nuclei of VII

-polysnaptic …uses an interneuron

37
Q

what happens after the motor fibers leave the motor nucleus of VII then loop around the nucleus of VI in the facial colliculus?

A

exit the low pons to eventually find the orbicularis oculi muscles to close both eyes

WE’RE AT THE PONS LEVEL

38
Q

wehre do the corneal reflex fibers terminate in

A

the rostral spinal nucleus of V

39
Q

if the left CN 7 is lesioned (a LMN or peripheral CN 7 palsy) and the right cornea is stimulated w/ a cotton wisp (light touch), what kind of response will you get

A

direct

40
Q

if the right CN 7 is lesioned and the right cornea is stimulated, what type of response will you get

A

consensual

41
Q

if the right CN 5 is lesioned and the right cornea is stimulated, what type of response will you get?

A

neither direct nor consensual

42
Q

what can a lesion to V3 on one side lead to

A

deviation of the mandule to the side of the lesion, strong pushes the weak
-compare right and left masseter msucles during jaw clench

43
Q

why do unilateral UMN lesions not produce jaw weakness?

A

bc the motor nuc of V gets bilateral UMN corticobulbars

44
Q

what can UMN lesions cause? how can it be tested and what are you looking for

A

hyperreflexia

-clinically tested w/ the jaw jerk refelx, wehre you are looking for abnomrally, prominent, exaggerated jaw jerk

45
Q

wehre do afferents of the jaw jerk refelx have its 1st cell body?

  • wehre do 1st order peripheral processes of the mesencephalic nucleus come from?
  • where is the central process sent out to synapse on?
A

NOT the trigeminal ganglion

  • 1st cell body for the proprioceptive afferents from the jaw actually is the mesencephalic nucleus
  • 1st order peripheral process of the mesencephalic nucleus comes from (innervates) the stretch receptors in the jaw for proprioception
  • sent out to synapse on the motor nucleus of V in the mid pons
46
Q

where does the efferent limb of the jaw jerk refelx send its motor axon to

A

jaw muscles to make them contract

47
Q

there is no cell body in the trigeminal ganglion for jaw proprioception, so it is …..

A

monosynpatic

48
Q

what is the weird exception to the CNS/PNS rule of gray matter and white matter

A

mesencephalic nucleus

Neuro Final (10 decks)

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