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Neuro Exam 3 > Occulomotor, trochlear, abducens > Flashcards

Occulomotor, trochlear, abducens Flashcards

1
Q

how to remember which extraocular muscles are not innervated by CN III and what they are innervated by

A

LR6SO4
Lateral rectus 6
Sup Oblique is 4

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2
Q

Rectus muscles of eye

A

do as name implies (sup –> up)

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3
Q

Oblique eye mucles

A

move eye opposite of eye implies (sup oblique moves eye down) - this is because the tendon wraps around

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4
Q

levator palpebrae

A

holds eye open

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5
Q

holds eye open

A

levator palpebrae

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6
Q

location of the occulomotor n.

A

extends 5mm rostrocaudally near the midline in the mesencephalon at the level of the sup. colliculus

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7
Q

Cells in the oculomotor complex

A

multiple columns of cells, each containing neurons that send somatic efferents to specific extraocular muscles

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8
Q

Axons of oculomotor cortex go where

A

they go ventrally to exit medial to the cerebral peduncles

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9
Q

dorsomedial and sup part of oculomotor complex

A

Edinger westphal nucleus which carries visceral (parasympathetic preganglionic) efferents to ciliary ganglion

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10
Q

CN III runs from _______ space to ______

A

subarachnoid space to the cavernous sinus; passes between sup cerebellar and post cerebral arteries on its way and by uncus of the temporal lobe

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11
Q

CN III runs _____ to CN IV, VI, and V1 in the sinus

A

superior to

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12
Q

CN III divides into superior division and inf where

A

at the sup orbital fissure

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13
Q

Split of CN III that supplies preganglionic outflow to ciliary ganglion

A

inferior division

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14
Q

Inf. divison of CN III supplies

A

inf and med rectus, inf oblique, and preganglionic outflow to ciliary ganglion

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15
Q

Sup division of CN III supplies

A

Sup rectus and levator palpebrae

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16
Q

Damage to CN III

A

eyelid drooping and dilated eye b/c parasympathetics run with it so no constricting

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17
Q

The oculomotor complex lives where in the brain, leaves where

A

midbrain, leaves out the sup. orbital fissure into the orbit and divides into branches that go to the 5 muscles

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18
Q

N. that also lives in midbrain

A

CN III and Trochlear (CNIV)

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19
Q

only nerve to exit brain dorsally; then goes out through

A

trochlear; sup orbital fissure to SO m. –> tilts eye down

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20
Q

Small and wispy CN

A

Trochlear

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21
Q

Where CN IV leaves vault; where does it go? what does it do?

A

goes dorsally, goes into cavernous sinus below CN III, leaves out Sup orbital fissure to SO m. to tilt eye down and in

22
Q

Lesion to trochlear n.

A

causes eye to turn up and out (extorsion) which causes double vision; person tilts head forward and to opposite side to see

23
Q

double vision is mainly caused by

A

damage to trochlear n.

24
Q

which n. causes a horizontal gaze

A

abducens

25
Q

where in the brain is abducens n.

A

in the pons, seperated from 4th ventricle by facial n.

26
Q

which CN is located in the pons

A

Abducens, CN VI

27
Q

CN that coordinates horizontal gaze

A

Abducens

28
Q

Axons of abducens –> ______ –> pierce _____ –> emerge between _____ and _____ –> ascend along the base of ____ –> travel below _____

A 
ventrally
medial leminiscus
pons and medulla
pons
Gruber's ligament
29
Q

In the lateral wall of the cavernous sinus Abducens n. lies between ______ medially and _________ laterally

A

carotid artery

opthalmic branch of trigeminal laterally (V1)

30
Q

Contents and order (sup to inf) of cavernous sinus

A

ICA < III, IV, VI, V1 and V2 (NOT V3)

31
Q

aneurism of internal carotid artery would first effect which nerve

A

abducens, sits closest to the int. carotid a. in the cavernous sinus, CN III, IV, V2, and V3 are all more lateral

32
Q

PPRF

A

Paramedian Pontine Reticular Formation-aka Horizontal Gaze Center; a collection of nuerons located near the midline of the pons; innervate abducens nuclei on the same side of the brain and oculomotor complex on the opposite side

33
Q

Two types of neurons that PPRF innervate of abducens nucleus

A

motor neurons that innervate LR on same side (moves lat)
Internuclear neurons –> send axons across midline –> ascend in medial longitudinal fasciculis –> terminate i
oculomotor complex which innervates medial rectus m. are

34
Q

internuclear neurons of the abducens nucleus send axons where

A

across the midline –> ascend in medial longitudinal fasciculis (mlf) –> terminate in oculomotor complex which targets medial rectus m.

35
Q

activation of PRRF on the right does what

A

causes both eyes to gaze to the right

36
Q

How many abducens nuclei does PRRF project to?

A

Just ONE! but… each abducens nuclei has two neurons that will target lateral and medial rectus

37
Q

controls horizontal gaze

A

PRRF

38
Q

Controls vertical gaze

A

riMLF

39
Q

riMLF

A

rostral interstitial nucleus of medial longitudinal fasciculus (riMILF) in the midbrain, controlled by frontal eye fields in the frontal lobe

40
Q

Location of riMILF

A

in the midbrain

41
Q

riMLF is controlled by

A

frontal eye fields in the frontal lobe, that sit infront of the motor cortex; this projects to the oculomotor complex or all the way back to the PRRF

42
Q

Frontal eye fields

A

in frontal lobe infront of motor cortex, control riMLF and thus vertical gaze; project to oculomotor complex or PRRF

43
Q

lesion in the right abducens (look left and right)

A

left –> ok b/c LR is ok b/c oculomotor ok

Right –> oh no, 2x vision b/c MR is a goner

44
Q

Lesion in R abducens nucleus

A

Da faq, nothing happens, cannot look right b/c both MR shot

45
Q

Lesion in R PRRF

A

gaze left is fine

Gaze right –> cannot, loss of LR on that side and opposite MR

46
Q

Lesion in MLF left

A

gaze left –> fine
Gaze right –> only right eye (contralateral) can b/c other lost MR; the one that can move does not want to (nystagmus) and leads to left intranuclear opthalmoplegia (INO)

47
Q

Nystagmus

A

when only one eye is able to move, the other shoots back into place

48
Q

Can be the result of having one MLF out

A

intranuclear opthalmoplegia on the opposite side (INO)

49
Q

lesion in Left MLF and L Abducens nucleus

A

knocks out left MR and right MR and left LR; good luck

cannot look left at all
can move right eye laterally but cannot move left eye M so causes nystagmus;
this mess is 1 1/2 syndrome; where one horizontal gaze is completely paralyzed and half of the other is

50
Q

Class including CN III, IV, and VI

A

Strictly motor; general somatic efferents; innervate skeletal m. derived from somites during embrylogical development

Neuro Exam 3 (7 decks)

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