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LECOM MS1 Gross Anatomy - Head/Neck 2022 (+Shelf) > Cranial Nerves (Details) > Flashcards

Cranial Nerves (Details) Flashcards

(57 cards)

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1
Q

CN I (Olfactory Nerve)

A

big picture: smell
testing: smell coffee, soap, oreos
injury: pt can’t smell, anosmia

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2
Q

CN II (Optic Nerve)

A

big picture: vision
testing: ophthalmoscope (check retina), visual acuity + visual fields
S/S: blindness, abnormal pupillary light reflex, visual field deficits (blindness/blind spots)

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3
Q

CN III (Oculomotor Nerve)

A

big picture: eye movements
testing:“H” pattern
S/S: diplopia, ptosis
accommodation (near triad) info -> pupillary light reflex
S/S: anisocoria, abnormal pupillary light reflex

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4
Q

CN IV (Trochlear Nerve)

A

big picture: eye movements
testing: “H” pattern, look in and down
S/S: diplopia

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5
Q

CN V (Trigeminal Nerve)

A

big picture: sensation on face, nasal + oral cavity
testing: sensation on face, corneal reflex
S/S: sensory loss on face
muscles of mastication -> clench teeth, palpate masseter S/S: asymmetric jaw closing

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6
Q

CN VI (Abducens Nerve)

A

big picture: eye movements
testing: “H” pattern, abduction
S/S: diplopia, lateral gaze palsy

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7
Q

CN VII (Facial Nerve)

A

muscles of facial expression -> smile, wrinkle forehead facial S/S: asymmetry&raquo_space; hyperacusis
tears and saliva -> pt complaint
S/S: dry eye, mouth
taste -> sugar/salt/lemon juice
S/S: loss of taste on anterior 2/3 of tongue
sensation on ear - -

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8
Q

CN VIII (Vestibulocochlear Nerve)

A

hearing -> tuning fork (Weber, Rinne tests)
S/S: decreased hearing/deafness
balance -> vestibulo-ocular reflex, caloric testing
S/S: dizziness, vertigo

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9
Q

CN IX (Glossopharyngeal Nerve)

A

swallowing -> gag reflex
S/S: dysphagia
saliva - dry mouth (xerostomia)
taste - loss of taste post 1/3 of tongue

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10
Q

CN X (Vagus Nerve)

A

muscles of larynx/pharynx/esophagus speech
testing: gag, cough, elevate palate
S/S: hoarseness, dysphagia, sagging palate
parasympathetics to foregut - -
taste (root/epiglottis) - -

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11
Q

CN XI (Spinal Accessory Nerve)

A

trap + SCM
testing: shrug shoulders, turn/tilt head
S/S: weakness shrugging shoulder

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12
Q

CN XII (Hypoglossal Nerve)

A

tongue muscles (not palatoglossus)
testing: protrude tongue
S/S: dysarthria tongue deviates on protrusion

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13
Q

What stimulates trigeminal nerve endings on CN I?

A

Ammonia (irritating compounds)

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14
Q

How can CN I be damaged?

A

Head trauma

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15
Q

Where can CN II be damaged?

A

Optic canal, orbit, subarachnoid space

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16
Q

How is CN II affected?

A

demyelination (e.g. multiple sclerosis), aneurysm, infarct, trauma, pituitary tumor, craniopharyngioma

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17
Q

What are the signs of injury of CN II?

A

vision loss/blindness, Marcus-Gunn pupil (afferent pupillary defect = on swinging light test, the pupil in the affected/blind eye appears to dilate when exposed to light)

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18
Q

Where can CN III be damaged?

A

midbrain (stroke), subarachnoid space (aneurysm), cavernous sinus, orbit (compare injury to the superior and inferior divisions of this nerve)

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19
Q

What are the signs of injury of CN III?

A

marked ptosis, mydriasis (“blown pupil”; compare to Horner’s Syndrome), pupil is directed “down and out” from unopposed action of lateral rectus + superior oblique

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20
Q

What occurs in a compressive injury of CN III?

A

Aneurysm, abscess
- a painful and complete oculomotor palsy that involves the pupil is most often an aneurysm
- compressive injuries can affect the pupil but spare eye movements (because of the superficial location of the GVE axons in CN III)

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21
Q

What occurs in the ischemic injury of CN III?

A

Diabetic infarct -> a painless oculomotor palsy that spares the pupil is most often microvascular

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22
Q

Where does CN III hitchhike?

A

Postganglionic GVE axons distribute to the eye along short ciliary nerves

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23
Q

Where can CN IV be damaged?

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A

midbrain (stroke), subarachnoid space (because of the long intracranial course, CN IV is at particular risk with head trauma), cavernous sinus, orbit

24
Q

What are signs of injury of CN IV?

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A

vertical diplopia (worse when walking down stairs), affected eye is hypertropic and extorted

25
How does diplopia improve with CN IV injury?
diplopia is improved by head tilt to side opposite the lesion/affected eye (with chin tucked) and worsened by head tilt towards the affected eye (Bielschowsky sign)
26
What can CN V be damaged in?
- pons (stroke) - posterior cranial fossa (meningioma) - ophthalmic nerve: cavernous sinus; superior orbital fissure, branches in orbit and on face - maxillary nerve: cavernous sinus; foramen rotundum, branches in nasal cavity and face - mandibular nerve: foramen ovale, infratemporal fossa, branches to mandible and face
27
Where can structures be anesthetized?
- infraorbital n - mental n - incisive/nasopalatine n - buccal n - mandibular n - auriculotemporal - inferior alveolar n
28
What is ophthalmic herpes?
- 10-15% of all herpes zoster cases - infection in trigeminal ganglion and vesicular eruption in distribution of ophthalmic nerve - Hutchinson’s sign: rash present on tip of nose – this indicates involvement of the nasal branch of the nasociliary nerve and increased risk of ophthalmic complications (uveitis, keratitis, conjunctivitis, blindness - from irritation of the cornea, choroid, retina, optic n)
29
What is trigeminal neuralgia?
- pain along the distribution of ophthalmic, maxillary or mandibular nerves, but usually NOT restricted to one trigeminal dermatome - most often caused by compression from blood vessels, tumors, or multiple sclerosis - becomes life-threatening if pain interferes with eating/drinking
30
Where can CN VI be damaged?
pons (stroke), subarachnoid space/posterior fossa, cavernous sinus (infection, aneurysm), orbit
31
What is CN VI in direct contact with?
Internal carotid artery within the cavernous sinus -> risk of injury with aneurysm in this location
32
What are the signs of injury of CN VI?
horizontal diplopia, cannot abduct eye; esotropia (affected eye is partially adducted)
33
How is diplopia caused by CN VI improved?
head turn (in horizontal plane) towards affect eye
34
Where can CN VII be damaged?
- in the pons/medulla/posterior cranial fossa (pontocerebellar angle) - in the temporal bone: internal auditory meatus (CN VIII tumor), facial canal, stylomastoid foramen, base of skull (during forceps delivery), trauma - on face (parotid surgery, trauma)
35
Where can injuries of CN VII occur?
- motor root: pt may complain of dry eye/pain because they cannot completely close their eyelids - nervus intermedius - facial n. at internal auditory meatus - greater petrosal n. - nerve to stapedius - chorda tympani - facial n. in facial canal - facial n. at exit from stylomastoid foramen
36
What is Bell palsy?
- an acute, peripheral facial palsy - patient : ▪ is unable to close lips and eyelids ▪ has difficulty eating (food stuck between cheek and teeth) ▪ is unable to whistle
37
What is the Bell phenomenon?
upon attempted closure of the eyelids, both eyes normally (reflexively) elevate (look upward), easily visible due to paralysis of orbicularis oculi
38
What is Crocodile Tears Syndrome?
after Bell’s palsy (or other proximal injury to CN VII), GVE axons originally destined for the submandibular ganglion get re-routed or make connections to the PPG, resulting in lacrimation at the sight/smell of food
39
What is Ramsay Hunt syndrome (herpes oticus)
- Herpes infection in the geniculate ganglion - s/s: facial paralysis + vesicular eruptions in the external meatus (occasionally dizziness, tinnitus and hearing loss)
40
What are the major hitchhikers of CN VII?
- greater petrosal n – joins deep petrosal nerve (postganglionic sympathetic GVEs) to form nerve of the pterygoid canal; the parasympathetic axons synapse in PPG, postganglionic axons distribute with branches of maxillary n. ▪ axons destined for the lacrimal gland transfer to the lacrimal n (from ophthalmic) - chorda tympani n – joins lingual n, GVE axons synapse in submandibular ganglion, postganglionic axons distribute with branches of lingual nerve ▪ compare signs and symptoms of injury to the lingual nerve before and after it is joined by the chorda tympani
41
What can CN VIII injury cause?
IL deafness, nystagmus, dizziness
42
What can vestibular schwannoma impact?
CN VII, CN V, and CN VIII
43
Where can CN IX be damaged?
- medulla (stroke), posterior cranial fossa (tumor, aneurysm) - main trunk: jugular foramen, base of the skull, tonsillar fossa - tympanic n (Jacobson’s nerve): middle ear (carries the pain of otitis media) - lesser petrosal n: middle cranial fossa (abscess, tumor, trauma)
44
What is glossopharyngeal neuralgia?
characterized by episodes of repeated episodes of severe pain in the tongue, ear, pharynx and tonsillar regions; episodes are often triggered by yawning, swallowing or coughing; often caused by vascular compression
45
Where does CN IX hitchhike?
Auricotemporal nerve
46
Where can damage to CN X occur?
- medulla (stroke), posterior cranial fossa (tumor, aneurysm) - main trunk: jugular foramen → base of skull → carotid sheath superior laryngeal n · internal laryngeal n – trauma, lymphadenopathy · external laryngeal n – ligation of superior thyroid artery ▪ recurrent laryngeal n (at aortic arch – aneurysm, surgical repair of PDA; ligation of inferior thyroid artery)
47
What are some key points on jugular foramen and vagus nerve?
 The auricular branch of CN X (Arnold’s nerve) provides sensory innervation to the external ear and meatus; pathology or stimulation here can result in nausea or cough  The jugular foramen is formed along the petro-occipital suture by the jugular process of the occipital bone and the jugular fossa of the petrous part of the temporal bone
48
Where does CN XI arise from?
Neurons in C1-C4 spinal cord
49
What can impact CN XI injury?
In spinal cord, foramen magnum, posterior fossa or jugular foramen - results in atrophy, weakness and fasciculations of the SCM and trapezius
50
Injury in the posterior triangle of CN XI will affect...
Only the trapezius
51
What does injury to lower motor neurons or axons of CN XII cause?
atrophy, fasciculations and a tongue that on protrusion deviates to the side of the lesion
52
Where can CN XII be injured?
- medulla (stroke), posterior cranial fossa (aneurysm) - hypoglossal canal (occipital bone) – compression of the occipital condyles in a newborn may result in poor suckling - base of skull; neck/submandibular region (here CN XII carries C1 to the thyrohyoid, geniohyoid and superior root of the ansa cervicalis) - oral cavity
53
What are the sensory ganglia of the head?
TGIS -> trigeminal, geniculate, superior and inferior CN IX and superior and inferior CN X
54
What are specific axons in the trigeminal nerve?
GSA
55
What are specific axons in the geniculate?
GSA, GVA+ SVA
56
What are the specific axons in the superior and inferior IX?
GSA, SVA, GVA
57
What are the specific axons in the superior and inferior X?
GSA, SVA, GVA

LECOM MS1 Gross Anatomy - Head/Neck 2022 (+Shelf) (29 decks)

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