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

Cranial Nerves (Details) Flashcards

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?

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?

A

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

25
Q

How does diplopia improve with CN IV injury?

A

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
Q

What can CN V be damaged in?

A
  • 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
Q

Where can structures be anesthetized?

A
  • infraorbital n
  • mental n
  • incisive/nasopalatine n
  • buccal n
  • mandibular n
  • auriculotemporal
  • inferior alveolar n
28
Q

What is ophthalmic herpes?

A
  • 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
Q

What is trigeminal neuralgia?

A
  • 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
Q

Where can CN VI be damaged?

A

pons (stroke), subarachnoid space/posterior fossa, cavernous sinus (infection, aneurysm), orbit

31
Q

What is CN VI in direct contact with?

A

Internal carotid artery within the cavernous sinus -> risk of injury with aneurysm in this location

32
Q

What are the signs of injury of CN VI?

A

horizontal diplopia, cannot abduct eye; esotropia (affected eye is partially adducted)

33
Q

How is diplopia caused by CN VI improved?

A

head turn (in horizontal plane) towards affect eye

34
Q

Where can CN VII be damaged?

A
  • 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
Q

Where can injuries of CN VII occur?

A
  • 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
Q

What is Bell palsy?

A
  • 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
Q

What is the Bell phenomenon?

A

upon attempted closure of the eyelids, both eyes normally (reflexively) elevate (look upward), easily visible due to paralysis of orbicularis oculi

38
Q

What is Crocodile Tears Syndrome?

A

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
Q

What is Ramsay Hunt syndrome (herpes oticus)

A
  • Herpes infection in the geniculate ganglion
  • s/s: facial paralysis + vesicular eruptions in the external meatus (occasionally dizziness, tinnitus and hearing loss)
40
Q

What are the major hitchhikers of CN VII?

A
  • 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
Q

What can CN VIII injury cause?

A

IL deafness, nystagmus, dizziness

42
Q

What can vestibular schwannoma impact?

A

CN VII, CN V, and CN VIII

43
Q

Where can CN IX be damaged?

A
  • 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
Q

What is glossopharyngeal neuralgia?

A

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
Q

Where does CN IX hitchhike?

A

Auricotemporal nerve

46
Q

Where can damage to CN X occur?

A
  • 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
Q

What are some key points on jugular foramen and vagus nerve?

A

 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
Q

Where does CN XI arise from?

A

Neurons in C1-C4 spinal cord

49
Q

What can impact CN XI injury?

A

In spinal cord, foramen magnum, posterior fossa or jugular foramen - results in atrophy, weakness and fasciculations of the SCM and trapezius

50
Q

Injury in the posterior triangle of CN XI will affect…

A

Only the trapezius

51
Q

What does injury to lower motor neurons or axons of CN XII cause?

A

atrophy, fasciculations and a tongue that on
protrusion deviates to the side of the lesion

52
Q

Where can CN XII be injured?

A
  • 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
Q

What are the sensory ganglia of the head?

A

TGIS -> trigeminal, geniculate, superior and inferior CN IX and superior and inferior CN X

54
Q

What are specific axons in the trigeminal nerve?

A

GSA

55
Q

What are specific axons in the geniculate?

A

GSA, GVA+ SVA

56
Q

What are the specific axons in the superior and inferior IX?

A

GSA, SVA, GVA

57
Q

What are the specific axons in the superior and inferior X?

A

GSA, SVA, GVA

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

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