Cranial Nerves in Neuroscience Flashcards
1
Q
Cranial Nerves
A
CNI: Olfactory CNII: Optic CNIII: Oculomotor CNIV: Trochlear CNV: Trigeminal CNVI: Abducens CNVII: Facial CNVIII: Vestibulocochlear CNIX: Glossopharyngeal CNX: Vagus CNXI: Accessory CNXII: Hypoglossal
2
Q
All cranial nerves are dorsal in the brainstem except…
A
Trochlear: Wraps around from ventral side
Olfactory: Not on brainstem
3
Q
Superior Orbital Fissure (CN exit points)
A
CN 3, 4, 5 (V1: opthalmic), 6
4
Q
Foramen Rotundum (CN exit points)
A
CN5 (V2: Maxillary)
5
Q
Foramen Ovale (CN exit points)
A
CN5 (V3: Mandibular)
6
Q
Internal Auditory Canal (CN exit points)
A
CN8
7
Q
Sylomastoid Foramen (CN exit points)
A
CN7
8
Q
Hypoglossal Canal (CN exit points)
A
CN12
9
Q
Internal Jugular Foramen (CN exit points)
A
CN9, 10, 11
10
Q
Foramen Magnum (CN exit points)
A
None
11
Q
Olfactory Nerve (CNI)
A
- Chemoreceptors detect odor, located in nasal epithelium
- Chemoreceptors synapse in olfactory bulb, info travels via olfactory tract
- Chemoreceptors> Bulb> Tract
- Chemoreceptors (Mitral & tufted cells)
12
Q
Olfactory Nerve (CNI) Deficits
A
- Anosmia: Olfactory Sensory Loss
- Unilateral Deficits: Patient rarely aware; other nostril compensates
- Bilateral Deficits: Accompanied with decreased taste
- Causes: Head trauma, Viral infections, PD, Az, Intracranial lesions
13
Q
Optic Nerve (CNII)
A
- Synapses on LGN of thalamus
- Before Optic Chiasm: Optic Nerve
- After Optic Chiasm: Optic Tract
- Recall all vision deficits from unit 8
14
Q
A
(monocular visual loss)
-Total blindness of right eye due to complete lesion of right optic nerve
15
Q
A
Bilateral hemianopia due damage of the optic chiasm (loss of temporal vf)
16
Q
A
Right nasal hemianopia due to lesion involving right perichiasmal area
17
Q
A
- Left Contralateral homonymous hemianopia due to damage of…
- LGN
- Occipital Lobe
- Optic Tract
- Optic Radiations
- MCA Stem Infarct
- PCA Infarct
- Primary Visual Cortex
18
Q
A
Left contralateral inferior quadrantanopia due to involvement of superior right optic radiations (or upper bank)
19
Q
A
Left contralateral superior quadrantanopia due to involvement of lower right optic radiations (meyers loop or lower bank)
20
Q
Optic Nerve (CNII) Visual Field Deficits (image)
A
21
Q
Oculomotor (CNIII), Trochlear (CNIV), Abducens (CNVI)
A
- Always grouped together
- ALL control extraocular eye muscles
22
Q
Trochlear Nerve (CNIV)
A
Rotates top of eye medially and moves downward
23
Q
Abducens Nerve (CNVI)
A
Abducts eye laterally in horizontal direction
24
Q
Oculomotor Nerve (CNIII)
A
ALL OTHER EYE MOVEMENTS
25
Trigeminal Nerve (CNV)
```
-3 Divisions
Opthalmic (V1): Superior Orbital Fissure
Maxillary (V2): Rotundum
Mandibular (V3): Ovale
-All do sensory to face, small motor portion to V3 for mastification
-Cells here located in Meckels cave
```
26
Trigeminal Nerve (CNV) Deficit
Trigeminal Neuralgia: Tix Douloureux
- Brief severe pain lasting seconds to minutes
- Episodes caused from chewing, shaving, anything to the face (sensory to face)
- Cause unknown, usually occurs in MS patients (due to demyelination, can be treated with medication)
27
Facial Nerve (CNVII)
- Controls muscles of facial expression (blinking, frowning, smiling, facial droop)
- Also tear production (lacrimal duct and gland), salivation, taste 2/3 tongue
28
Facial Nerve (CNVII)
Facial Weakness: UMN & LMN
- UMN Lesion: Upper face spared, signal bilaterally ascends causing contralateral presentation
- LMN Lesion: (after pons) Upper and lower face affected (bells palsy), presents ipsilaterally
29
Facts about Bell's Palsy (CNII)
- Quick recovery in about 80% of patients within 3 weeks
- Divisions of the nerve are impaired then recover
- Unknown cause
- Will not show on MRI
30
Vestibulocochlear Nerve (CNVIII)
Dual purposes: Hearing and vestibular sense from inner ear
31
Outer: Parts of the Ear
Pinna> External Auditory Canal> Tympanic Membrane (ear drumb)
32
Middle: Parts of the Ear
3 Ossicles: Malleus, Incus, Stapes (vibrate sound)> Tensor Tympani & Stapedius Muscle (attached to ossicles to regulate vibrations & protect ear from really loud noises)> Oval & Round Window (air is converted into waves)
33
Inner: Parts of the Ear
Bony Labyrinth & Membranous Labyrinth > Central Duct
34
Organ of Corti (Parts of the Ear)
Receptor for Hearing (within cochlea which is in membranous labyrinth)
35
Within the Cochlea (CNIII)
2 Main Ducts
1. Scala Vestubuli
2. Scala Tympani
- Central Duct/Scala Media
36
Scala Vestubuli (ducts within cochlea)
Sound vibrations enter here from oval window and transmits sound waves
37
Scala Tympani (ducts within cochlea)
Found at apex, spirals around and ends at round window
38
Central Duct/Scala Media (ducts within cochlea)
Surrounded by scala vestibule above and scala tympani below
39
Bony Labyrinth: Yellow
| Membranous Labyrinth: Purple (contains cochlea, semi-circular canals, and vestibulae)
40
High vs. Low Frequencies (CNVIII)
- High Frequencies activate hair cells at oval window (ex. high pitched voices)
- Low Frequencies activate hair cells near apex of cochlea (ex. deeper voices)
41
Depolarization (CNVIII)
Stereocilia bends to kinocilia
42
Hyperpolarization (CNVIII)
Stereocilia bends away kinocilia
43
Within the inner ear, we have our organ of corti which is the sensory receptor for...
Hearing
44
We have hair cells within the organ of corti that are going to move...
Inward as sound travels through the ear (depolarization) and move back to neutral (hyperpolarization) as sound is transferred
45
Synapses for Auditory (CNVIII)
Medial geniculate nucleus of the thalamus
46
Primary Auditory Cortex (CNVIII)
Heschel's Gyrus
47
Secondary Auditory Cortex (CNVIII)
Wenicke's
48
Auditory information ascends... (CNVIII)
Bilaterally with decussations at multiple levels. No unilateral hearing deficits
49
Damage to Wernicke's Area (CNVIII)
- Does not affect hearing
| - Affects interpretations of hearing (wernicke's aphasia)
50
Damage to one side of CN 8
- Only has little effect on our hearing because of the collaterals/cross-over connections
- Similar to ALS tract in the spinal cord
- Volume may be “turned down” but it isn’t muted
51
Unilateral Hearing Loss
Structural
52
3 Vestibular Components of CN 8
- Peripheral sensory apparatus
- Central processor
- Mechanism for motor output
53
Peripheral Sensory Apparatus (3 Vestibular Components of CN 8)
"Balance Center"
| -Visual, vestibular, proprioceptive
54
Central Processor (3 Vestibular Components of CN 8)
Vestibular nuclei in the cerebellum
55
Mechanism for Motor Output (3 Vestibular Components of CN 8)
Direct connection
- Vestibulospinal tract
- Tectospinal tract and eye muscles
56
Semicircular Canals (CNVIII)
Are receptors for vestibular information
57
3 Semicircular Canals (CNVIII)
- Right and left lateral
- Left. anterior and right posterior
- Left posterior and right anterior
58
Semicircular Canals detect...
Angular acceleration and rotational movements of head in space
- Detected by the Crista ampullaris (sensory receptor)
- Work together with our vision
59
Ampula (CNVIII)
- At the base of our SCCs
- The little bulge
- These contain the christa ampullaris
60
Crista Ampularis (CNVIII)
- Primary sensory structure responding to vestibular info
- The “base” of the troll hair
- Hair cells on top of crista ampularis that project into the cupula
61
Cupula (CNVIII)
Shifts the opposite way from where we turn our heads
| *Keeps the balance
62
Otoliths
-Utricle: response to gravity in horizontal plane
Example: riding in a car
-Saccule: response to gravity in vertical plane
Example: riding in an elevator
*sensory receptor for otoliths- MACULA
-Within otoliths, there are otoconia. These are crystals.
-When these crystals travel outside of the otoliths, someone can have BPPV.
-More receptors for vestibular info
-Still within the membranous labyrinth
-Different than the crista ampullaris
63
Lesion to Vermis (cerebellum: CNVIII)
-Gait ataxia, trunk instability, balance
64
Lesion to flocculus (cerebellum: CNVIII)
-Issues with gain of VOR
| VOR= Ratio of eye movement to head movement
65
VOR and VSR (cerebellum: CNVIII)
VOR: Purpose is to keep vision stable while the head is moving (vestibular ocular reflex)
VSR: Purpose is to keep head and body stabilized (vestibular spinal reflex)
66
Vestibular input (cerebellum: CNVIII)
- Going to the vermis and flocculus
| - Monitors vestibular performance and keeps it in check (error detector, movement corrector)
67
Vestibulocochlear Nerve (CNVIII) Deficits
-Gold standard to determine hearing loss: Audiometry test= Audiogram
-Vestibular Neuritis
-Vestibular Labrinthitis
-Meninere's Disease
(see also BPPV and Acoustic neuroma in notes)
68
Vestibular Neuritis (CNVIII Deficits)
Inflammation of vestibular ganglia or nerve, does not cause hearing loss. Intense vertigo for days and loss of postural control for weeks to months
69
Vestibular Labyrinthitis (CNVIII Deficits)
Same presentation as vestibular neuritis but HEARING LOSS.
70
Meninere's Disease (CNVIII Deficits)
Excess fluid and pressure, lifetime disease, recurrent episodes of vertigo and fluctuating hearing loss and tinnitus- ringing in ear
71
Clinical tests to determine what type of hearing loss (Vestibulocochlear Nerve (CNVIII)
- Rinne Test
| - Weber Test
72
Rinne Test (Clinical tests to determine hearing loss type, CNVIII)
- Used to determine conduction hearing loss by comparing bone to air conduction- strike tuning fork then place on mastoid process. Damage in middle ear. (conductive hearing loss)
- Tuning fork outside ear= soft
- Tuning fork on mastoid= louder
- With deficit= hear fork on bone
- W/o deficit= hear fork in air
73
Weber Test (Clinical tests to determine hearing loss type, CNVIII)
- Used to determine sensorineural hearing loss by placing tuning fork in center of skull
- Place tuning fork on skull, sound is quieter on affected side.
- Damage in cochlea (inner ear), due to prolonged exposure to sounds.
- With deficit= hear fork in air
- W/o deficit= hear fork on skull
74
Rinne Test (image)
"Rinne under the pinne"
75
Weber Test (image)
"weber its right or left"
76
Glossopharyngeal Nerve (CNIX)
Sensation for posterior tongue and pharynx- also salivation and carotid body reflexes
77
Vagus Nerve (CNX)
- Largest innervation to organs
| - Parasympathetic innervation to organs (heart, lungs, digestive tract)
78
Spinal Accessory Nerve (CNXI)
- Sternocleidomastoid: Turns head opposite direction
- Upper trapezius: Elevates shoulder
- LMN Deficits: Ipsilateral weakness in shoulder shrug, Not able to turn head away from side of lesion
79
Hypoglossal Nerve (CNXII)
- Tongue movement
- Contralateral weakness of tongue- UMN lesion
- Ipsilateral weakness of tongue- LMN lesion= (hypoglossal nucleus or below)
- Dysarthria: abnormal articulation of speech
- Dysphagia: impaired swallowing
- Red flags for PT/OT: aspiration pneumonia
80
Horner’s Syndrome (CNXII)
Disruption of sympathetic nerves
- Ptosis: Drooping of eyelid
- Small pupils
- Miosis: Increased sweating
- Anhydrosis: Can’t sweat on face
- Enophthalmos: Eye falls into cavity
81
Vagus Nerve Impairment (CNXII)
- Dyspnea: Difficulty breathing
- Dysphonia: Difficulty speaking
- Dysphagia: Difficultly swallowing
- Dysarthria: Abnormal production of speech
- Tachycardia (inc HR)
82
Dysarthria
-Abnormal production of speech
| CN V, VII, IX, X, XII
83
Dysphagia
-Difficulty swallowing
| CN XII, IX, X, or XII
