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Anatomy - BB Exam 3 > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

which cranial nerves are especially susceptible to compression or injury related to pathologies of sinus? why?

A

3, 4, V1, 6 - due to close relationship to cavernous sinus

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2
Q

anosmia

A

loss of smell

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3
Q

things associated with anosmia

A
  • upper respiratory infection
  • sinus disease
  • head trauma
  • aging
  • tumor/abscess in frontal lobe
  • tumor of meninges in anterior cranial fossa
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4
Q

what do people usually complain of w/ anosmia and why?

A

lost or altered taste - b/c most people confuse taste with flavor

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5
Q

allergic rhinitis

A

inflammation of nasal mucous membrane - causes transitory olfactory impairment

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6
Q

how do you test for sense of smell?

A

person blindfolded and asked to ID common odors, like coffee

-test each nostril separately b/c anosmia is usually unilateral

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7
Q

rhinorrhea

A

leakage of fluid through the nose

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8
Q

meningioma

A

tumor of meninges

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9
Q

what are olfactory hallucinations and when can you get them?

A

false perceptions of smell - lesions in temporal lobe

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10
Q

what could a lesion of lateral olfactory area, deep to uncus, cause?

A

temporal lobe epilepsy/uncinate fits - imaginary bad odors + involuntary movements of lips and tongue

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11
Q

what can cause CN I lesion that causes anosmia and CSF rhinorrhea?

A

fracture of cribriform plate

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12
Q

what can cause CN II lesion that causes loss of pupillary constriction? (2 things)

A
  • direct trauma to orbit or eyeball

- fracture involving optic canal

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13
Q

what can cause CN II lesion that results in visual field defects? (2 things)

A
  • pressure on optic pathway

- laceration or intracerebral clot in temporal, parietal, or occipital lobes

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14
Q

what can cause CN III lesion that results in:
-dilated pupil
-ptosis
-eye turns down and out
-pupillary reflex on side of lesion lost
(3 things)

A
  • pressure from herniating uncus on nerve
  • fracture involving cavernous sinus
  • aneurysms
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15
Q

what can cause CN IV lesion that results in inability to look down when eye is adducted? (2 things)

A
  • stretching of nerve during its course around brainstem

- fracture of orbit

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16
Q

what can cause CN V lesion that results in:
-loss of pain and touch sensations
-paresthesia
-masseter and temporalis mm. do not contract
-deviation of mandible to side of lesion w/ open mouth
(2 things)

A
  • injury to terminal branches (particularly V2) in roof of maxillary sinus
  • pathological processes affecting trigeminal ganglion
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17
Q

what can cause CN VI lesion that results in:
-eye fails to move laterally
-diplopia on lateral gaze
(2 things)

A
  • lesion of base of brain

- fracture involving cavernous sinus or orbit

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18
Q

what can cause CN VII lesion that results in:

  • paralysis of facial muscles
  • eye remains open
  • angle of mouth droops
  • forehead does not wrinkle
A

laceration or contusion in parotid region

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19
Q

what can cause CN VII lesion that results in:

  • paralysis of facial muscles
  • eye remains open
  • angle of mouth droops
  • forehead does not wrinkle
  • associated involvement of cochlear n. and chorda tympani
  • dry cornea
  • loss of taste on anterior 2/3 of tongue
A

fracture of temporal bone

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20
Q

what can cause CN VII lesion that results in:

  • forehead wrinkles b/c of bilateral innervation of frontalis
  • otherwise paralysis of contralateral facial muscles
A

intracranial hematoma “stroke”

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21
Q

what can cause CN VIII lesion that results in:

  • progressive unilateral hearing loss
  • tinnitus
A

tumor of nerve (acoustic neuroma)

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22
Q

what can cause CN IX lesion that results in:
-loss of taste on posterior 1/3 of tongue
-loss of sensation on affected side of soft palate
(2 things)

A
  • brainstem lesion

- deep laceration of neck

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23
Q

what can cause CN X lesion that results in:
-sagging of soft palate
-deviation of uvula to normal side
-hoarseness owing to paralysis of vocal fold
(2 things)

A
  • brainstem lesion

- deep laceration of neck

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24
Q

what can cause CN XI lesion that results in:

  • paralysis of SCM and descending fibers of trapezius
  • drooping of shoulder
A

laceration of neck

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25
Q

what can cause CN XII lesion that results in:
-protruded tongue deviates toward affected side
-moderate dysarthria (disturbance of articulation)
(2 things)

A
  • neck laceration

- fractures of cranial base

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26
Q

what nerve is susceptible to demyelinating diseases of CNS and why? what is an example of one such disease?

A

optic nerves - they are actually CNS tracts - myelin sheath formed by oligodendrocytes instead of Schwann cells
-MS (multiple sclerosis)

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27
Q

optic neuritis

A

lesions of the optic nerve that cause diminution of visual acuity, w/ or w/o changes in peripheral fields of vision

-optic disc is pale and smaller than normal

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28
Q

what can cause optic neuritis?

A

inflammatory, degenerative, demyelinating, or toxic disorders

29
Q

what causes visual field defects?

A

lesions that affect different parts of visual pathway

30
Q

what visual field defects result from complete section of an optic nerve?

A

blindness in the temporal and nasal visual fields of the ipsilateral eye

31
Q

what visual field defects result from complete section of the optic chiasm?

A

reduces peripheral vision - bitemporal hemianopsia (loss of vision of 1/2 of the visual field of both eyes

32
Q

what visual field defects result from complete section of the right optic tract at the midline?

A

eliminates vision from left temporal and right nasal visual fields - contralateral homonymous hemianopsia (visual loss in similar fields)

33
Q

what is the most common type of visual field loss and in what patients is it often seen?

A

contralateral homonymous hemianopsia (section or either right or left nerve) - seen in stroke patients

34
Q

what does a lesion of CN III result in?

A

ipsilateral oculomotor palsy

35
Q

CN III compression: where can it be compressed, and what is the first sign?

A
  • crest of petrous part of temporal bone

- ipsilateral slowness of pupillary response to light

36
Q

what can cause CN III compression?

A
  • rapid increase in intracranial pressure (from extradural hematoma)
  • aneurysm of a posterior cerebral or superior cerebellar artery
  • injuries or infections of cavernous sinus
37
Q

characteristic sign of a trochlear nerve injury

A

diplopia when looking down - b/c SO normally assists the IR in depressing pupil and is the only muscle to do so when pupil is adducted

38
Q

how can a patient compensate for diplopia caused by trochlear nerve injury?

A

inclining head anteriorly and laterally toward side of the normal eye

39
Q

what does injury to CN V cause? (4 things)

A
  • paralysis of muscles of mastication w/ deviation of mandible towards side of lesion
  • loss of ability to appreciate soft tactile, thermal, or painful sensations on face
  • loss of corneal reflex
  • loss of sneezing reflex
40
Q

what are common causes of facial numbness? (6 things)

A
  • dental trauma
  • herpes zoster ophthalmicus
  • cranial trauma
  • head and neck tumors
  • intracranial tumors
  • idiopathic trigeminal neuropathy
41
Q

trigeminal neuralgia is also called?

A

tic douloureux

42
Q

what is trigeminal neuralgia/ tic douloureux?

A

produces excruciating, episodic pain that is usually restricted to areas supplied by the maxillary and/or mandibular divisions of trigeminal n. (from compression of nerve)

43
Q

what is the principal disease of the sensory root of CN V?

A

tic douloureux

44
Q

which nerve is most often blocked during dental anesthesia administration?

A

inferior alveolar nerve from V3

45
Q

what does complete paralysis of CN VI cause?

A
  • medial deviation of affected eye due to unopposed action of MR m.
  • diplopia always
46
Q

what can cause CN VI paralysis? (4 things)

A
  • space occupying lesion, such as brain tumor
  • aneurysm of cerebral arterial circle
  • pressure from an atherosclerotic internal carotid a. in the cavernous sinus
  • septic thrombosis of sinus subsequent to infection in nasal and/or paranasal cavities
47
Q

what is the most frequently paralyzed of motor CNs?

A

CN VII

48
Q

what does a lesion of CN VII near it’s origin or near geniculate ganglion cause?

A
  • loss of motor, gustatory, and autonomic functions

- motor paralysis on superior and inferior ipsilateral parts of face

49
Q

what does a central lesion of CN VII cause?

A
  • motor paralysis on contralateral inferior face

- can still wrinkle forehead

50
Q

Bell’s palsy

A

unilateral facial paralysis of sudden onset resulting from a lesion of CN VII

51
Q

what can lesions of CN VIII cause?

A
  • tinnitis
  • vertigo
  • impairment/loss of hearing
52
Q

two kinds of deafness?

A
  1. conductive deafness: involves external or middle ear

2. sensorineural deafness: involves disease in cochlea or in pathway from cochlea to brain

53
Q

acoustic neuroma

A

neurofibroma - slow-growing benign tumors of Schwann cells that begins in the vestibular nerve while in the internal acoustic meatus

54
Q

symptoms of acoustic neuroma

A
  • loss of hearing (early symptom)
  • dysequilibrium
  • tinnitis
55
Q

vertigo

A

hallucination of movement involving the person or the environment

  • often a spinning sensation or swaying back and forth
  • comes w/ nausea, vomiting
56
Q

what type of nerve lesion is vertigo typically associated with?

A

peripheral vestibular nerve lesion

57
Q

losses in isolated CN IX lesion?

A
  • no taste on posterior 1/3 of tongue
  • no gag reflex
  • ipsilateral weakness - change in swallowing
58
Q

jugular foramen syndrome

A

tumors in region of jugular foramen produce multiple cranial nerve palsies - IX, X, XI all run through jugular foramen

59
Q

glossopharyngeal neuralgia

A

sudden intensification of burning or stabbing pain often initiated by swallowing, protruding tongue, talking, or touching palatine tonsil

  • uncommon
  • unknown cause
60
Q

what do injury to pharyngeal branches of CN X cause?

A

dysphagia

61
Q

what does injury to superior laryngeal nerve cause?

A
  • anesthesia of superior part of larynx
  • paralysis of cricothyroid muscle
  • weak voice that tires easily
62
Q

what does injury to recurrent laryngeal nerve cause?

A

-hoarseness
-dysphonia (difficulty speaking)
(paralysis of vocal cords)

63
Q

what does paralysis of both recurrent laryngeal nerves cause?

A
  • aphonia - loss of voice

- inspiratory stridor

64
Q

what is inspiratory stridor?

A

harsh, high pitched respiratory sound

65
Q

which recurrent laryngeal nerve is more commonly injured and why?

A

left - b/c of its longer course

66
Q

iatrogenic injury of CN XI

A

physician-caused injury that may occur during surgical procedures such as:

  • lymph node biopsy
  • cannulation of internal jugular vein
  • carotid endarterectomy
67
Q

what does injury to CN XII do?

A

paralyzes ipsilateral half of tongue

-atrophy of that side of tongue

68
Q

which side does the tongue protrude to in CN XII injury?

A

-protruded tongue deviates toward paralyzed side b/c of unopposed action of the genioglossus muscle on normal side of tongue

Anatomy - BB Exam 3 (13 decks)

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