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Neuro Block 6 > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

Where are the cranial nerves attached?

A

To nuclei in brainstem. When you test CN, you test brainstem, cerebrum, and peripheral nerves

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2
Q

What do we test when we test for Pupillary light reflex (constriction)

A

CN 2 and 3

In on 2, out on 3

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3
Q

What do we test when we test Oculomotor system

A

Full range of conjugate eye movements

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4
Q

What do we test when we test trigeminal system

A

Somatosenation from face; muscles of mastication

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5
Q

What do we test when we test the facial nerve system (7)

A

Muscle of facial expression, weakness, where

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6
Q

What do we test when we test the corneal blink reflex?

A

CN 5 and 7, in on 5, out on 7

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7
Q

What do we test when we test vestibular sensation?

A

CN 8, dizziness

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8
Q

What do we test when we test vestibular-ocular reflex?

A

CN 8 and 6

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9
Q

What do we test when we test speech and swallowing?

A

CN 10, also test to see if hours. Motor deficit, not language

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10
Q

What do we test when we test head movement and shoulder elevation

A

CN 11

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11
Q

What do we test when we test for tongue protrusion on midline?

A

CN 12

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12
Q

Nasal VF is processed by what

A

Temporal retina

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13
Q

Temporal visual fields processed by

A

Nasal retina

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14
Q

Left visual field processed by what

A

Right optic tracts, right thalamus, and right cortex

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15
Q

Right visual field processed by

A

Left optic tracts, left thalamus, and left cortex

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16
Q

What parts of VF does optic nerve carry in each eye?

A

Both. Carries all parts of the VF back and they split at the chiasm

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17
Q

Optic tracts carry what info

A

From only one half of space. Left half of space, right tract, right cerebral hemisphere

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18
Q

What is the pupillary light reflex mediated by?

A

Optic nerves/tracts and midbrain

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19
Q

Pupillary light reflex

A
  • in on CN 2, out on CN 3
  • shining light into right eye activates sensory arc following optic tracts bilaterally to pretectal nucleus in midbrain
  • each pretectal nucleus sends axon projections bilaterally to the left and right ending edinger-westphal nucleus to activate pre ganglionic parasympathetic neurons
  • post gang parasympathetic neurons in left and right ciliary ganglion activate pupillary constrictor muscles in both eyes (direct and consensual response)
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20
Q

What kind of light do you test pupil light reflex in?

A

Dim so that pupils are in a dilated state

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21
Q

Optic nerve lesion

A

Bilateral sensory issues when that ONE eye is tested. When other eye is tested, it bypasses and gets normal response because motor arc intact

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22
Q

If you shine in a light in the left eye and you get direct and consensual, and then you shine in light in the right eye and get NEITHER direct or consensual response, where is the lesion?

A

Lesion on right optic nerve

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23
Q

Lesion at CN3

A
  • lost motor arc on right only
  • not matter what, no constriction in right
  • lost parasympathetic tone, pupil dilates

No direct or consensual at all in the eye on the side that the oculomotor nerve is affected!!!

Sensory arc intact bilaterally, motor is only intact on left

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24
Q

Both eyes adduct

A

Vergence (CN3)

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25
Q

PERLA

A

Pupils equal and reactive to light and accommodation

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26
Q

Pupillary reflex for near vision

A
  • vergence
  • pupils constrict: motor arc mediated by parasympathetic from edinger-Westphalia via CN3 as with light induced constriction
  • reflex circuitry for accommodation not well established
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27
Q

is accommodation a specific test only of the midbrain?

A

No because the reflex circuitry for accommodation is not yet well established; may involve visual cortex or unconscious visual processing in tectum

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28
Q

If pupils are abnormally asymmetrical in size

A

Anisocoria

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29
Q

Questions to ask if anisocoria is present

A
  • is the asymmetry due to impaired pupillary restriction in the larger pupil?
  • is the asymmetry due to the impaired pupillary dilation in the smaller pupil?
  • does the asymmetry remain the same after testing for dilation and light reflex? If so and if there is an absence of EOM deficits, probably a benign asymmetry
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30
Q

What is usually a benign asymmetry when you see anisocoria?

A

Asymmetry remains the same after testing for dilation and light reflex and there is an absence of EOM deficits

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31
Q

Speed and magnitude of light induced constriction

A

Equally reactive

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32
Q

Damage to any part of the motor arc (mediated by sympathetic) of pupillary dilation is called

A

Horners syndrome

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33
Q

Horners syndrome

A
  • ipsilateral deficit in pupillary dilation

- ipsilateral eyelid dropping

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34
Q

Pupillary dilation in response to dim light

A
  • sensory arc: projections from retinal gang cells to a nucleus in hypothalamus
  • hypothalamic neurons send descending projections though lateral part of the brainstem to the pre gang sympathetic neurons in the IML column of thoracic spinal cord
  • activate motor arc
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35
Q

Any problem in lateral columns will result in

A

Horners probably

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36
Q

Where are possible lesion sites for there to be horners?

A

Chests spinal cord, and brainstem

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37
Q

Left oculomotor nerve lesion

A
  • left pupil remains dilated under normal light and does not respond to direct or consensual response at all.
  • there may be associated ptosis and eye movement abnormalities
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38
Q

Left horners syndrome

A
  • dilation lag in going from light to dark.
  • will constrict to direct and consensual
  • anisocoria
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39
Q

Left afferent pupillary defect

A
  • aka Marcus gunn pupil
  • when light shown in left eye, no direct or consensual
  • when light shown in normal eye, you get normal direct and consensual
  • test us using swinging flashlight test
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40
Q

Benign essential anisocoria

A

The same relative anisocoria is present in all lighting conditions. No dilation lag

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41
Q

Rx side effects on pupils

A

Opiate drugs and opioids Rx can act directly at the iris by inhibiting sympathtic (noradrenergic) activation of the dilator muscle, leads to pin-point pupils=bilateral constriction

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42
Q

Where is the oculomotor nucleus and the trochlear nucleus ?

A

Midbrain

43
Q

Where is the abducens nucleus

A

In the caudal pons.

44
Q

What is the abducens nuclear store linked to

A

The 3rd nucleus for conjugate eye movements

45
Q

Muscles innervated by oculomotor nucleus and trochlear nucleus in the midbrain and the abducens nucleus in the caudal pons

A 
Superior rectus
Levator palpebrae superioris
Medial rectus
Inferior rectus
Inferior oblique 
Superior oblique 
Lateral rectus
46
Q

Abducens

A

Lateral rectus

47
Q

Trochlear nerve innervation

A

Superior oblique

48
Q

CN 3 innervation

A 
Medial rectus
Superior rectus
Medial rectus 
Inferior oblique 
Levator palpebrae superioris
49
Q

Roles of CN 3

A 
Abduction 
Elevation
Depression
Adduction during conjugate eyemovements 
Adduction of both eyes during vergence/convergence
50
Q

Functions of the trigeminal system

A
  • somatosenation from face
  • oral sensation (general, not taste)
  • LMNs to muscles of mastication
  • corneal eye blink reflex (in on 5, out on 7)
51
Q

Trigeminal system responsible for fine/discriminative touch processed through

A

Chief/main/principal nucleus and joins the DC-ML system

52
Q

Trigeminal system responsible for pain/temp/crude touch processed where

A

Through spinal trigeminal nuclear secrets and parallels the ALS

53
Q

Where are the first order neurons for the trigeminal pain/temp/crude touch system?

A

With cell body in the trigeminal ganglion

54
Q

How does the 1st order neuron run in the trigeminal system for pain/temp/crude touch

A

Trigeminal ganglion in pons DOWN to the medulla, crosses the midline and goes back UP parallel to the anteriolaterla system

55
Q

Trigeminal motor nucleus (Vm) innervates

A

Ipsilateral muscles of mastication

56
Q

Trigeminal motor nucleus: corticonclear innervation and function

A

It has bilateral activation, so can compensate for loss of the other side if there is a lesion

57
Q

Where does each trigeminal motor nucleus receive UMN innervation from

A

BOTH left and right precentral gyri

58
Q

Unilateral LMN lesions in trigeminal motor nucleus

A

Paralyze ipsilateral muscles

59
Q

UMN lesions in the trigeminal motor nucleus

A

Do not paralyze muscles die to intact innervation from upper motorneurons from other side of the cortex. Some subtle weakness may result but not paralysis

60
Q

What controls the upper face

A

Orbicularis oculi and frontal belly

61
Q

What controls the lower face

A

Everything other than the orbicularis oculi and the frontal belly

62
Q

What do you have people do with their face when testing them?

A

Raise eyebrows
Shut eyes tightly
Smile and frown
Blow or hold air in mouth without leaking

63
Q

Where do UMN in lower face synapse?

A

Contralteral cortex

64
Q

Where do LMN of lower face synapse

A

Pons

65
Q

Facial nucleus motorneurons for the upper face receive innervation from where

A

UMN in the left AND right motor cortex

66
Q

Facial nucleus motorneurons for the lower face receive innervation from where

A

ONLY from the contralateral motor cortex

67
Q

Central Seven lesion - a unilateral lesion to the face area of motor cortex–or axonal projections of these UMN results in what

A

Motor deficits only for the lower face. The upper face muscles can still be activated bilaterally because the LMN still receive innervation from the motor cortex on the intact side. Can still shut both eyes tight, raise both eyebrows, and wrinkle both sides of forehead. HAS DROPPING OF CORNER OF MOUTH

68
Q

Bell’s Palsy-facial nerve lesion or lesion to the facial nucleus produces what

A

Unilateral full face paralysis. Cannot shit eyes tightly, raise eyebrows, wrinkle forehead, smile or frown, hold air in mouth. Also, dropping of corner of eye and mouth

69
Q

Facial motor nucleus innervates

A

Ipsilateral muscles of facial expression

70
Q

Each upper face subnucleus receives what

A

UMN innervation from both left and right precentral gyrus

71
Q

Lower face subnucleus innervated by what

A

Only by contralateral precentral gyrus

72
Q

Corneal blink reflex

A

Multilevel reflex circuitry involving trigeminal and facial nerve systems

  1. touch cornea on one side activates corneal nocireceptors
  2. Activates ophthalmic division of ipsilateral trigeminal nerve (V1)
  3. Fibers enter pons, descend and synapse in spinal trigeminal nucleus (ipsilateral)
  4. Post syn neurons in spinal trigeminal nucleus (medulla) ascend and terminate bilaterally in facial nuclei to bilaterally activate the orbicularis oculi (both)
  5. must be sure blink was caused by touch, not blink-to-threat
73
Q

Damage to spinal trigeminal T and N, right side

A

Touch right cornea: neither eye blinks (sensory arc damaged, motor arc in tact)

Touch left cornea: both eyes blink (sensory arc intact, motor arc intact)

74
Q

If damage only to facial nucleus on right side (corneal blink reflex)

A
  • sensory arc intact bilaterally, motor arc intact on left but damaged on right
  • touch right cornea: right eye fails to blink, but left eye blinks
  • touch left cornea: right eye fails to blink, but left eye blinks
75
Q

Vestibulocochlear nerve: auditory and vestibular systems

A
  • 1st order neurons in cochlea and semi circular canals, with cell bodies in spiral or vestibular ganglia
  • 1st order sensory neurons project to auditory or vestibular nuclei in rostral medulla-lateral and dorsal/posterior location
  • ascending pathways to cerebral cortex mediate conscious sensation
76
Q

Glossopharyngeal nuclei and all functions

A
  • taste from posterior third of tongue
  • carotid body and sinus: baroreceptors and chemoreceptors to solitary tract in brainstem
  • sensory feedback for Gag reflex: solitary tract and GVA part of solitary nucleus
77
Q

Glossopharyngeal nuclei and functions: sensory

A
  • caroti body and sinus-cardiovascular reflexes (in on 9, out on 10)
  • soft palate, sensory arc of gag reflex (in on 9, out on 10)
78
Q

Glossopharyngeal nuclei and functions: motor

A

Minor contribution to control of palate (stylopharyngeus)relative to 10

79
Q

Vagus: Dorsal motor nucleus of the vagus

A

Parasympathetic pre ganglionics

80
Q

Vagus: Nucleus ambiguus: CN 9 and 10

A

Innervation of skeletal muscles, innervation of soft palate, larynx, and pharynx

81
Q

Motor functions of Am (nucleus ambiguus)

A

Swallowing, gag reflex, focalization

82
Q

Vagus:: nucleus solitaris

A

Baroreceptors/viscerosensory info via 9 or 10 nerves to solitarius

83
Q

Vagus: spinal trigeminal nucleus

A

Somatosenation from outer ear follows CN 10 to spinal trigeminal nucleaus (spT)

84
Q

Gag reflex

A
  • in on 9, out on 10
  • sensory arc mediated by IX nerve
  • directed to nucleus ambiguus
  • indirectly via excitatory internuerons which project into nucleus ambiguus
  • possibly via IX projections to nucleus solitarius, then to nucleus ambiguus

Motor arc mostly mediate by CN 10

85
Q

In gag reflex, what is the sensory arc mediate by

A

CN 9

86
Q

In gag reflex, what is the motor arc mediated by

A

CN 10

87
Q

If right N ambiguus is damaged (LMN lesion)

A

Right soft palate droops, uvula deviates to left

88
Q

Innervation to levator palatini (say”ah”)

A

N ambiguus via CN X

89
Q

If right corticonuclear projections are damaged, then loss of innervation to _____

Upper motorneuron lesion

A

Left N ambiguus, left soft palate droops, uvula deviates to right side

90
Q

Neural control of swallowing (deglutition)

A
  • tongue movement propels bolts into oropharynx
  • sensory info from oropharynx (9 transmitted to N solitarius)
  • reflexive elevation of palate (mostly CN10, also CN9, both from N ambiguus)
  • course of laryngeal inlet (epiglottis) and elevation of larynx via CN 10
91
Q

Impairment in any aspect of voice quality/function due to any cause

A

Dysphonia

92
Q

Hoarseness or difficulty in focalization due to a motor impairment-paralysis, paresis, spasticity, impaired motor coordination of vocal muscles (weakness on one side of larynx)

A

Dysarthria

93
Q

CNS control of voalization

A
  • N ambiguus, X nerves internal/recurrent laryngeal nerves
  • lateral vascular territory
  • UMN/precentral gyrus control: ipsilateral larynx
94
Q

Testing accessory nucleus and nerve function

A
  • Trapezius tested by shrugging. CONTRALATERAL CORTEX

- sternocleidomastoid swings head toward opposite side, strength tested against resistence IPSILATERAL CORTEX

95
Q

Trapezius strongly controlled by

A

Contralateral cortex

96
Q

Sternocleidomastoid strongly controlled by

A

Ipsilateral cortex

97
Q

Hypoglossal nucleus and nerve function (tongue muscle)

A

Easy to test with the genioglossus muscle. Nucleus in medulla

98
Q

Vascular territory of the hypoglossal nucleus

A

Medial anterior spinal artery

99
Q

Hypoglossal nerve and tongue protrusion test (genioglossus)

A
  • tongue protrudes straight forward on midline

- weakness or paralysis on one side leads to deviation toward weak side

100
Q

Hypoglossal upper motor neurons

A
  • Right UMN target left hypoglossal nucleus
  • left UMN target right hypoglossal nucleus
  • corticonuclear projections descend ipsilateral
  • projections cross midline at target level
101
Q

UMN lesion, left side in hypoglossal nerve

A

Right side weakness, tongue deviates towards right

102
Q

LMN lesion, left side of hypoglossal nerve

A
  • left side weakness

- tongue deviates to left

103
Q

LMN signs in tongue

A

Tongue atrophy and fasciculations

-LMN signs in hypoglossal nuclei in medulla, an hypoglossal nerve

Neuro Block 6 (8 decks)

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