Cranial Nerves Flashcards
(103 cards)
1
Q
Where are the cranial nerves attached?
A
To nuclei in brainstem. When you test CN, you test brainstem, cerebrum, and peripheral nerves
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
3
Q
What do we test when we test Oculomotor system
A
Full range of conjugate eye movements
4
Q
What do we test when we test trigeminal system
A
Somatosenation from face; muscles of mastication
5
Q
What do we test when we test the facial nerve system (7)
A
Muscle of facial expression, weakness, where
6
Q
What do we test when we test the corneal blink reflex?
A
CN 5 and 7, in on 5, out on 7
7
Q
What do we test when we test vestibular sensation?
A
CN 8, dizziness
8
Q
What do we test when we test vestibular-ocular reflex?
A
CN 8 and 6
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
10
Q
What do we test when we test head movement and shoulder elevation
A
CN 11
11
Q
What do we test when we test for tongue protrusion on midline?
A
CN 12
12
Q
Nasal VF is processed by what
A
Temporal retina
13
Q
Temporal visual fields processed by
A
Nasal retina
14
Q
Left visual field processed by what
A
Right optic tracts, right thalamus, and right cortex
15
Q
Right visual field processed by
A
Left optic tracts, left thalamus, and left cortex
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
17
Q
Optic tracts carry what info
A
From only one half of space. Left half of space, right tract, right cerebral hemisphere
18
Q
What is the pupillary light reflex mediated by?
A
Optic nerves/tracts and midbrain
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)
20
Q
What kind of light do you test pupil light reflex in?
A
Dim so that pupils are in a dilated state
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
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
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
24
Q
Both eyes adduct
A
Vergence (CN3)
25
PERLA
Pupils equal and reactive to light and accommodation
26
Pupillary reflex for near vision
- 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
27
is accommodation a specific test only of the midbrain?
No because the reflex circuitry for accommodation is not yet well established; may involve visual cortex or unconscious visual processing in tectum
28
If pupils are abnormally asymmetrical in size
Anisocoria
29
Questions to ask if anisocoria is present
- 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
30
What is usually a benign asymmetry when you see anisocoria?
Asymmetry remains the same after testing for dilation and light reflex and there is an absence of EOM deficits
31
Speed and magnitude of light induced constriction
Equally reactive
32
Damage to any part of the motor arc (mediated by sympathetic) of pupillary dilation is called
Horners syndrome
33
Horners syndrome
- ipsilateral deficit in pupillary dilation
| - ipsilateral eyelid dropping
34
Pupillary dilation in response to dim light
- 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
35
Any problem in lateral columns will result in
Horners probably
36
Where are possible lesion sites for there to be horners?
Chests spinal cord, and brainstem
37
Left oculomotor nerve lesion
- 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
38
Left horners syndrome
- dilation lag in going from light to dark.
- will constrict to direct and consensual
- anisocoria
39
Left afferent pupillary defect
- 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
40
Benign essential anisocoria
The same relative anisocoria is present in all lighting conditions. No dilation lag
41
Rx side effects on pupils
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
42
Where is the oculomotor nucleus and the trochlear nucleus ?
Midbrain
43
Where is the abducens nucleus
In the caudal pons.
44
What is the abducens nuclear store linked to
The 3rd nucleus for conjugate eye movements
45
Muscles innervated by oculomotor nucleus and trochlear nucleus in the midbrain and the abducens nucleus in the caudal pons
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Superior rectus
Levator palpebrae superioris
Medial rectus
Inferior rectus
Inferior oblique
Superior oblique
Lateral rectus
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46
Abducens
Lateral rectus
47
Trochlear nerve innervation
Superior oblique
48
CN 3 innervation
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Medial rectus
Superior rectus
Medial rectus
Inferior oblique
Levator palpebrae superioris
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49
Roles of CN 3
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Abduction
Elevation
Depression
Adduction during conjugate eyemovements
Adduction of both eyes during vergence/convergence
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50
Functions of the trigeminal system
- somatosenation from face
- oral sensation (general, not taste)
- LMNs to muscles of mastication
- corneal eye blink reflex (in on 5, out on 7)
51
Trigeminal system responsible for fine/discriminative touch processed through
Chief/main/principal nucleus and joins the DC-ML system
52
Trigeminal system responsible for pain/temp/crude touch processed where
Through spinal trigeminal nuclear secrets and parallels the ALS
53
Where are the first order neurons for the trigeminal pain/temp/crude touch system?
With cell body in the trigeminal ganglion
54
How does the 1st order neuron run in the trigeminal system for pain/temp/crude touch
Trigeminal ganglion in pons DOWN to the medulla, crosses the midline and goes back UP parallel to the anteriolaterla system
55
Trigeminal motor nucleus (Vm) innervates
Ipsilateral muscles of mastication
56
Trigeminal motor nucleus: corticonclear innervation and function
It has bilateral activation, so can compensate for loss of the other side if there is a lesion
57
Where does each trigeminal motor nucleus receive UMN innervation from
BOTH left and right precentral gyri
58
Unilateral LMN lesions in trigeminal motor nucleus
Paralyze ipsilateral muscles
59
UMN lesions in the trigeminal motor nucleus
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
What controls the upper face
Orbicularis oculi and frontal belly
61
What controls the lower face
Everything other than the orbicularis oculi and the frontal belly
62
What do you have people do with their face when testing them?
Raise eyebrows
Shut eyes tightly
Smile and frown
Blow or hold air in mouth without leaking
63
Where do UMN in lower face synapse?
Contralteral cortex
64
Where do LMN of lower face synapse
Pons
65
Facial nucleus motorneurons for the upper face receive innervation from where
UMN in the left AND right motor cortex
66
Facial nucleus motorneurons for the lower face receive innervation from where
ONLY from the contralateral motor cortex
67
Central Seven lesion - a unilateral lesion to the face area of motor cortex--or axonal projections of these UMN results in what
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
Bell's Palsy-facial nerve lesion or lesion to the facial nucleus produces what
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
Facial motor nucleus innervates
Ipsilateral muscles of facial expression
70
Each upper face subnucleus receives what
UMN innervation from both left and right precentral gyrus
71
Lower face subnucleus innervated by what
Only by contralateral precentral gyrus
72
Corneal blink reflex
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
Damage to spinal trigeminal T and N, right side
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
If damage only to facial nucleus on right side (corneal blink reflex)
- 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
Vestibulocochlear nerve: auditory and vestibular systems
- 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
Glossopharyngeal nuclei and all functions
- 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
Glossopharyngeal nuclei and functions: sensory
- 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
Glossopharyngeal nuclei and functions: motor
Minor contribution to control of palate (stylopharyngeus)relative to 10
79
Vagus: Dorsal motor nucleus of the vagus
Parasympathetic pre ganglionics
80
Vagus: Nucleus ambiguus: CN 9 and 10
Innervation of skeletal muscles, innervation of soft palate, larynx, and pharynx
81
Motor functions of Am (nucleus ambiguus)
Swallowing, gag reflex, focalization
82
Vagus:: nucleus solitaris
Baroreceptors/viscerosensory info via 9 or 10 nerves to solitarius
83
Vagus: spinal trigeminal nucleus
Somatosenation from outer ear follows CN 10 to spinal trigeminal nucleaus (spT)
84
Gag reflex
- 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
In gag reflex, what is the sensory arc mediate by
CN 9
86
In gag reflex, what is the motor arc mediated by
CN 10
87
If right N ambiguus is damaged (LMN lesion)
Right soft palate droops, uvula deviates to left
88
Innervation to levator palatini (say"ah")
N ambiguus via CN X
89
If right corticonuclear projections are damaged, then loss of innervation to _____
Upper motorneuron lesion
Left N ambiguus, left soft palate droops, uvula deviates to right side
90
Neural control of swallowing (deglutition)
- 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
Impairment in any aspect of voice quality/function due to any cause
Dysphonia
92
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)
Dysarthria
93
CNS control of voalization
- N ambiguus, X nerves internal/recurrent laryngeal nerves
- lateral vascular territory
- UMN/precentral gyrus control: ipsilateral larynx
94
Testing accessory nucleus and nerve function
- Trapezius tested by shrugging. CONTRALATERAL CORTEX
| - sternocleidomastoid swings head toward opposite side, strength tested against resistence IPSILATERAL CORTEX
95
Trapezius strongly controlled by
Contralateral cortex
96
Sternocleidomastoid strongly controlled by
Ipsilateral cortex
97
Hypoglossal nucleus and nerve function (tongue muscle)
Easy to test with the genioglossus muscle. Nucleus in medulla
98
Vascular territory of the hypoglossal nucleus
Medial anterior spinal artery
99
Hypoglossal nerve and tongue protrusion test (genioglossus)
- tongue protrudes straight forward on midline
| - weakness or paralysis on one side leads to deviation toward weak side
100
Hypoglossal upper motor neurons
- Right UMN target left hypoglossal nucleus
- left UMN target right hypoglossal nucleus
- corticonuclear projections descend ipsilateral
- projections cross midline at target level
101
UMN lesion, left side in hypoglossal nerve
Right side weakness, tongue deviates towards right
102
LMN lesion, left side of hypoglossal nerve
- left side weakness
| - tongue deviates to left
103
LMN signs in tongue
Tongue atrophy and fasciculations
| -LMN signs in hypoglossal nuclei in medulla, an hypoglossal nerve
