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Visual System Anatomy > Motor innervation > Flashcards

Motor innervation Flashcards

1
Q

what is affected in a CN 3 nucleus lesion

A
  • ipsilateral MR, IR, IO
  • ipsilateral sphincter (dilated pupil),
  • cb muscle (lack of acc),
  • contra/ipsi SR
  • bilateral ptosis
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2
Q

what happens if lesion when follows of the superior+ posterior cerebral arteries around the cerebral peduncles

A

contralateral body weakness if lesion is close to the cerebral peduncles

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3
Q

what does cn4 follow

A

superior cerebellar and posterior cerebral arteries around the cerebral peduncle

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4
Q

inferior branch of cn3

A

io, ir, mr, parasympathetic, pupils-sphincter

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5
Q

lagopthalmos

A

obicularis cannot close eye properly –> dryness of cornea –> blindness usually with a cn 7 palsy

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6
Q

external ophthalmoplegia affected muscles

A

any or all eoms can be affected

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7
Q

cn6 fascicle location

A

within pons–> corticospinal tract (contra-weakness)

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8
Q

cn6 in cav sin

A
  • within the cav sin near ica
  • sympathetic fibers leave the ica + travel with the cn6 before splitting to cn3 or cn4
  • first nerve involved with ica aneurysm
  • horner’s usually occurs in the cav sin due to all the signs
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9
Q

where does the cn4 travel through (last step)

A

travels through the superior orbital fissure above the CTR outside the muscle cone

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10
Q

what is the CN3 most frequently affected by

A

posterior communicating artery aneurysm

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11
Q

what does the SR nuclei innervate

A

contralateral superior rectus

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12
Q

what does cn6 nucleus contain and what do they do

A

internuclear neurons that travel in the MLF to the contralateral MR nucleus

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13
Q

cn4 fascicle location

A

posterior

below the inferior colliculus

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14
Q

why are you relatively extorted in primary gaze

A
  • head tilt will force intorsion
  • head turn will force the bad eye to abduct so the rectus muscles control up and down movements
  • head is tilted downwards is the objects are more in line with the hyper eye
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15
Q

CN3 fascicle pathway

A
  • passes through ipsilateral superior cerebellar peduncle (ipsi ataxia)
  • through red nucleus (contra tremor)
  • through cerebral peduncle (CST- contra weakness)
  • passes through posterior cerebral artery + superior cerebellar artery
  • follows the posterior communicating artery
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16
Q

what curves around the cn6 nucleus

A

facial nucleus

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17
Q

CN3 fascicle pathway innervention

A
  • ipsilateral involvement of everything (MR, IR, IO, SR, levator, sphincter, CB)
  • contra eye is normal
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18
Q

procerus

A

(pulls eyebrows down + medially)

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19
Q

cn 6 clinical correlate- sharp bend over the petrous ridge

A

susceptible to compression and stretching injuries, particularly with increased ICP

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20
Q

superior branch of cn3

A

sr, levator

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21
Q

if lesion above sof and ctr

A

so palsy

numbness of forehead (cn5)

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22
Q

trochlear nerve nucleus location

A

midbrain at the level of the inferior colliculus

  • anterior to cerebral aqueduct
  • dorsal to MLF
  • caudal to cn3 nucleus
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23
Q

orbicularis

A

closes eyelids

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24
Q

what cranial nerves are involved in sensory for EOMS

A

2,5

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25
Q

cn6 lesion

A

gaze palsy innervation to LR to contralateral MR

26
Q

what does the edinger westphal nucleus innervate

A

iris, sphincter (miosis), cb (acc, cb contracts, parasympathetic)

27
Q

where wall does the cn4 enter

A

wall of cav sin

28
Q

cn 6 palsy - what deviation from primary position

A

esotropic deviation- greater at distance

29
Q

levator innervates

A

bilaterally

30
Q

the parasympathetic fibers are spared in

A

spared in ischemic lesion due to vasculature surrounding the nerve

first thing to go involved in compressive lesions, including an aneurysm or tumor

31
Q

cn 7 facial nucleus

A

loops around cn6 nucleus in pons

32
Q

what branches does the facial nerve divide int

A

temporal and zygomatic supplies the frontalis , procerus, corrugator, orbicularis

33
Q

what happens in a complete cn3 palsy

A
  • ptosis
  • the eye is positioned down and out due to the unopposed actions of the SO and LR
  • they cannot adduct (MR)
  • in the abducted position, cannot move up or down (SR, IR)
  • in the adducted position, they cannot move the eye up (IO)
  • pupil dilation
  • decreased acc
34
Q

what is the so palsy compensation

A

head tilt to the opposite shoulder

  • chin down
  • head turn towards
  • in lateral movements -abducts- turns head away from eye involved bc to abduct eye (rectus muscles to go up and down)-minimizes diplopia
35
Q

cn6 nerve pathway

A
  1. fascicle
  2. exit the groove between the pons and medulla
  3. runs along the occipital bone and posterior slope of the petrous portion of the temporal bone
    - -makes a sharp bend over the petrous ridge
  4. enters the cav sin
  5. enters the orbit through the superior orbital fissure within the ctr
36
Q

what does cn 6 (abducens) innervate

A

LR

37
Q

CN 4 pathway

A
  1. fascicle -below of inferior colliculus
  2. decussates
  3. follows the superior cerebellar and posterior cerebral arteries around the cerebral peduncle
  4. enters wall of cav sin
  5. travels through the SOF above the CTR
38
Q

cn6 palsy restriction

A

cannot abduct eye

39
Q

CN6 nucleus location

A
  • within in the pons

- contains the abducens motor neurons

40
Q

what does the trochlear nerve innervate

A

cn4

41
Q

cn 7 pathway

A
  1. fascicle travels around the abducens nucleus
  2. emerges from the brainstem at the lower border of the pons
  3. enters the internal acoustic foramen (w/ cn 8)
  4. exits the skull through the stylomastoid foramen
  5. divide into several branches
42
Q

what fibers are superficial on the cn3 nerve

A

parasympathetic

43
Q

when cn3 fascicle goes through ipsi superior cerebellar peduncle

A

ipsi ataxia

44
Q

what is an incomplete cn3 palsy

A

external ophthalmoplegia

45
Q

where is the oculomotor nerve located

A

midbrain @ superior colliculus

  • ventral to cerebral aquaduct
  • dorsal to MLF
46
Q

when cn3 fascicle goes through cerebral peduncle what happens

A

contra weakness

47
Q

what is within the lateral wall of the cav sin

A

cn 3,4,6

sympathetic fibers join after leaving the ICA (join to go to eyelids)

48
Q

what is spared in an external ophthalmoplegia

A

internal muscles (pupil, acc)

49
Q

what cranial nerves are involved in motor for EOMS

A

3,4,6

7-eyelids

50
Q

corrugator

A

(pulls eyebrowns medially)

51
Q

cn4 lesion

A

contralateral so palsy

52
Q

what is the first nerve the cav sin affected in ica aneurysm

A

cn 6

53
Q

cn 4 palsy

eye deviation in primary position

A

hyper deviation (bc SO normally pulls eye down)

54
Q

where is the oculomotor nerve subnuclei located

A

IR, IO, MR nuclei

-innervate ipsilateral eye

55
Q

when cn3 fascicle goes through red nucleus

A

contralateral tremor

56
Q

what does the oculomotor nerve innervate

A

IO, MR, SR, IR, Levator, pupils (sphincter), mullers

57
Q

cn 6 palsy compensation

A

turn head towards action of muscle to compensate (towards paralyzed side)

58
Q

cn4 restrictions

A

when adducted, eye won’t depress

59
Q

what is spared in internal ophthalmoplegia

A

eoms

60
Q

frontalis

A

(raises eyebrows)

61
Q

cn 7 functions

A
  • motor root –> facial muscles
  • sensory root –> taste
  • parasympathetic –> glands of face, lacrimal gland

Visual System Anatomy (10 decks)

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