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Neuro 1 > Cranial Nerves > Flashcards

Cranial Nerves Flashcards

1
Q

Location of LMN of

  1. CN III
  2. CN IV
  3. CN VI
A

dorsal midline brainstem

  1. ventral to superior colliculi (5 separate nuclei)
  2. ventral to inferior colliculi
  3. caudal half of pons immediately below facial colliculus in floor of 4th ventricle
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2
Q

CN III nuclei (midbrain)

  1. dorsal
  2. medial
  3. intermediate
  4. ventral
  5. central caudal

other eye nuclei

  1. Edinger-Westphal
  2. trochlear (midbrain)
  3. abducens (pons)
A
  1. inferior rectus
  2. contralateral superior rectus
  3. inferior oblique
  4. medial rectus
  5. bilateral levator palpebrae superior (voluntary)
  6. bilateral PNS
  7. superior oblique
  8. lateral rectus
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3
Q

What is unique about the trochlear nerve?

What other nuclei serves contralateral eye muscle (aka what LMN cross)?

A

innervates contralateral superior oblique muscle

Others are ipsilateral: CN III (except medial nucleus to superior rectus), VI, all other CN

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4
Q

Lesion of oculomotor nucleus on one side would affect up gaze how?

A

BOTH eyes can’t look up

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5
Q

Arteries and CN III

A
  1. Pcom
  2. superior cerebellar
  3. posterior cerebral
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6
Q

What provides ANS elevation of eyelid?

A

SNS on superior tarsal muscle

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7
Q

How can you test the

  1. superior rectus
  2. inferior rectus
  3. superior oblique
  4. inferior oblique
A
  1. out then up
  2. out then down
  3. in then down
  4. in then up

out: abduct
in: adduct

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8
Q

How can you differentiate between a complete and partial CN III lesion?

A

complete: closed eye, paralysis of all CN III muscles
partial: weakened CN III muscles, only partially closed eye

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9
Q

PCOM aneurysm

  1. first clue
  2. as it enlarges
A
  1. UNILATERAL PUPILLARY DILATATION (parasympathetics)
  2. PARESIS of CN III
    EMERGENCY
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10
Q

occlusion of small arteries supplying CN III

A

oculomotor paresis
WITHOUT unilateral pupil enlargement

due to DM or vasculopathies

still should get MRI to rule out Pcom aneurysm

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11
Q

UMN control of eye movements

A

MLF

PPRF

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12
Q

medial longitudinal fascicles (MLF)

lesion?

A

abducens nucleus fibers that activate contralateral ventral nucleus of CN III (medial rectus)

lesion: internuclear ophthalmoplegia: unable to adduct when looking in contralateral direction

ex: left MLF lesion:
look left: normal
look right: right eye nystagmus, left eye can’t adduct

right MLF lesion:
look right: normal
look left: right eye doesn’t adduct, left eye has nystagmus

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13
Q

paramedian pontine reticular formation (PPRF)

lesion?

A

regulates MLF: simultaneously activate lateral rectus and contralateral medial rectus to contract

lesion: can’t look to side of lesion with both eyes (eyes look away from lesion)

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14
Q

Right abducens nerve palsy vs. right abducens nucleus palsy

A

nerve: affected eye can’t abduct (can’t look toward lesion)
nucleus: both eyes can’t look to side of lesion (can’t activate contralateral medial rectus)

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15
Q

1 1/2 syndrome

A

same side MLF and abducens nucleus lesion

left lesion:
can’t look to left
right gaze: left eye doesn’t adduct, right eye has nystagmus

right lesion
can’t look right
left gaze: right eye doesn’t adduct, left eye has nystagmus

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16
Q

oculocephalic maneuver or Doll’s eyes

A

tests: vestibulo-ocular reflex (VOR): test pons/midbrain in comatose patient

eyes move in opposite direction when head is turned quickly

absence: lesion

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17
Q

vestibulo-ocular reflex

A

slow conjugate eye movement

  1. rotate head to one side stimulates ipsilateral semicircular canals
  2. ipsilateral vestibular nerve
  3. vestibular nucleus
  4. activates contralateral PPRF: look to opposite side of rotation
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18
Q

saccades

A

fast conjugate eye movements

voluntary or reflex

19
Q

pursuit movements

A

slow conjugate eye movements

20
Q

frontal eye fields

A

controls saccades

activates contralateral PPRF

lesion: can’t look to contralateral side (eyes look toward lesion)

21
Q

visual cortex

A

integrates frontal eye fields and POT

22
Q

parietal-occipito-temporal (POT) area

A

slow pursuit eye movements

controls ipsilateral side (look to side of POT)

lesion: can’t look to ipsilateral side

23
Q

opticokinetic (OKN) strip

A

alternating stripes: fix on stripes as you move it

tests slow pursuit and frontal eye fields

24
Q

frontal cortex lesion

A

eyes away from paresis

lesion: left frontal lobe: right hemiparesis and loss of right PPRF (right frontal eye field and left PPRF move eyes to left)

25
Q

pontine lesion

A

eyes toward paresis

lesion: left pons: right hemiparesis and loss of left PPRF

26
Q

nucleus ambiguus

A

nuclei for motor vagus and glossopharyngeal

27
Q

jaw jerk reflex

A
  1. tap lower jaw
  2. muscle spindles in masseter muscle send impulse through sensory cranial nerve V
  3. synapse in the mesencephalic nucleus of V
28
Q

CN V motor

  1. UMN input
  2. UMN lesion
  3. LMN lesion (CN V or its nuclei)
A
  1. bilateral
  2. no unilateral weakness; jaw jerk may increase
  3. unilateral weakness of jaw closure, reduced jaw jerk, atrophy of temporals and masseter
29
Q

CN VII motor

  1. UMN input
  2. UMN lesion
  3. LMN lesion
A
  1. bilateral for forehead, unilateral for lower face
  2. weak contralateral lower face; forehead spared
  3. ipsilateral paralysis of upper and lower face; hyperacusis (stapedius muscle, dry eye (pterygopalatine nerve)
30
Q

CN IX motor

  1. UMN lesion
  2. LMN lesion
A

dysphagia (mostly have to test under sensory conditions)

31
Q

CN X motor

  1. UMN lesion
  2. LMN lesion
A
  1. bilateral so no Sx

2. hoarseness, dysphagia, reduced gag reflex on stimulated side

32
Q

CN XI motor

  1. UMN lesion
  2. LMN lesion
A
  1. weak ipsilateral SCM and contralateral shoulder elevation

2. shoulder droop on side of lesion; weakness turning head to contralateral side of lesion

33
Q

CN XII motor

  1. UMN lesion
  2. LMN lesion
A
  1. tongue away from lesion

2. toward side of lesion

34
Q

primary visual cortex

A

calcarine fissure

35
Q

brachium of superior colliculus

A

some optic nerves bypass LGN to synapse in superior colliculus for visual startle reflex

36
Q

sensory innervation of external ear

A

anterior: CN V3
posterior: CN VII, IX, X

37
Q

organization of spinal tract and nucleus of V

A

most dorsal: CN VII, IX, X
V3
V2
most ventral: V1

38
Q

nucleus solitarius inputs

  1. rostral (gustatory nucleus)
  2. caudal
A
  1. input from CN VII, IX, X (taste)

2. cardiorespiratory inputs: VII, XI, X

39
Q

hair cells location

  1. auditory receptors
  2. vestibular receptors
A

CN VIII

  1. organ of Corti
  2. saccule, utricle, semicircular canals
40
Q

spiral ganglion

  1. axons via
  2. synapse on
  3. then where
  4. project to
  5. then to
A

cell bodies of auditory afferents

  1. CN VIII
  2. ipsilateral dorsal and ventral cochlear nuclei
  3. ascend bilaterally to inferior colliculus
  4. medial geniculate body
  5. transverse gyro in superior temporal lobe
41
Q

Herschel’s gyrus

A

transvers gyri in superior temporal lobe

42
Q 
vestibular ganglion (scarpa's ganglion)
1. synapse on
A

where vestibular hair cells synapse

1. vestibular nuclei

43
Q

______ vestibular nuclei gives rise to what

  1. superior
  2. lateral
  3. medial
  4. inferior
A
  1. MLF
  2. lateral vestibulospinal tract
  3. medial vestibulospinal tract, MLF
  4. medial vestibulospinal tract
44
Q

gag reflex

  1. what carries afferent limb
  2. where is the interneuron between afferent and efferent
  3. what mediates efferent response
A
  1. caudal solitary nucleus
  2. N. Ambiguus
  3. motoneurons in N. Ambiguus that travel with CN X

Neuro 1 (10 decks)

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