Neuro 13

Front 1

what are abnormalities of pupils and eye movements warning signs for

Back 1

signs of pathology in brainstem or CNs

Front 2

eye movement disorders and pathways are separated into what two levels

Back 2

1) nuclear and infranuclear pathways 2) supranuclear pathways

Front 3

nuclear and infranuclear pathways

Back 3

involve brainstem nuclei of CN III, IV, and VI; peripheral nerves arising from these nuclei; eye movement muscles

Front 4

supranuclear pathways

Back 4

involve brainstem and forebrain circuits that control eye movements through connections with nuclei of CN III, IV, and VI

Front 5

what eye muscles originate on a tendinous ring at the orbital apex and insert onto the sclera

Back 5

lateral, medial, superior, and inferior rectus muscles

Front 6

where does the superior oblique originate

Back 6

sphenoid bone in posterior medial orbit and passes anteriorly through trochlea; inserts on superior surface of eye (intorsion-upper pole inward)

Front 7

where does the inferior oblique originate

Back 7

along the anterior medial orbital wall and inserts on the inferior surface of the eye (extorsion-upper pole outward)

Front 8

what eye CNs pass through cavernous sinus and enter orbit via superior orbital fissure

Back 8

III (oculomotor), IV (trochlear), and VI (abducens)

Front 9

what muscles does CN III innervate

Back 9

all extraocular except lateral rectus and superior oblique; levator palpebrae superioris; preganglionic parasympathetic fibers to pupillary constrictor muscles and ciliary muscles of lens

Front 10

trochlear innervates

Back 10

superior oblique

Front 11

abducens innervates

Back 11

lateral rectus

Front 12

what constitute the somatic motor column of CN nuclei

Back 12

III, IV, VI, along with XII (hypoglossal); all near midline adjacent ventricular system and fibers exit brainstem ventrally near midline (except IV which exits dorsally)

Front 13

where are oculomotor nuclei

Back 13

upper midbrain at level of superior collliculi and red nuclei, just ventral to the periaqueductal gray matter

Front 14

where does CN III exit brainstem

Back 14

in interpeduncular fossa btwn posterior cerebral and superior cerebellar arteries

Front 15

what does the Edinger-Westphal nucleus contain

Back 15

preganglionic parasympathetic fibers

Front 16

what are parasympathetics controlling pupil constriction in CN III susceptable to

Back 16

run in superficial portion of nerve as travels in subarachnoid space - susceptible to compression from aneurysms (especially via posterior communicating artery)

Front 17

location of trochlear nuclei

Back 17

lower midbrain at level of inferior colliculi and decussation of superior cerebellar peduncle

Front 18

abducens nuclei location

Back 18

floor of 4th ventricle under facial colliculi in mid-to-lower pons; exit at pontomedullary jxn

Front 19

Dorello's canal

Back 19

abducens nerve travels in-outside dura running btwn dura and skull under petroclinoid ligament

Front 20

diplopia causes

Back 20

1) mechanical (fracture) 2) disorders of extraocular muscles (thyroid disease, orbital myositis) 3) disorders of neuromuscular jxn (myasthenia) 4) disorders of CN III, IV, VI and central pathways

Front 21

what can cause monocular diplopia or polyopia

Back 21

opthalmological disease, disorders of visual cortex, or psychiatric conditions

Front 22

extropia

Back 22

abnormal lateral deviation of one eye

Front 23

estropia

Back 23

abnormal medial deviation of one eye

Front 24

hypertropia

Back 24

vertical deviation of one eye with respect to other eye

Front 25

phoria

Back 25

mild weakness present only with an eye covered (instead of tropia)

Front 26

remaining movements of eye with complete disruption of CN III and resting position

Back 26

some abduction (abducens) and some depression and intorsion (superior oblique); eye down and out at rest with complete ptosis and dilated pupil unresponsive to light

Front 27

red glass testing with 3rd-nerve palsy

Back 27

diagonal diplopia most severe when looking up and medially with affected eye

Front 28

common causes of oculomotor nerve palsy

Back 28

diabetic neuropathy and head trauma (shear forces); compression by intracranial aneurysms; infection, tumor, venous thrombosis, herniation of medial temporal lobe

Front 29

what aneurysms tend to affect CN III

Back 29

jxn of Pcomm with internal carotid; less common = jxn Pcomm and PCA, basilar & PCA jxn, or basilar & SCA jxn

Front 30

what do aneurysms classically cause

Back 30

painful oculomotor palsy that involves the pupil; may be subtle or complete

Front 31

what is complete oculomotor palsy that spares the pupil usually caused by

Back 31

diabetes

Front 32

trochlear nerve palsy

Back 32

vertical diplopia (normally causes depression and intorsion of eye)

Front 33

how do ppl with trochlear nerve palsy compensate

Back 33

looking up (chin tuck) and tilting head away from affected eye (compensate for hypertropia and extorsion)

Front 34

when is depressing action of superior oblique most pronounced

Back 34

when eye is adducted

Front 35

head movement and eye abnormalities

Back 35

moves in same direction normally served by the affected muscle

Front 36

causes of vertical diplopia

Back 36

trochlear nerve palsy, myasthenia gravis, lesions of superior division of CN III (superior rectus), and skew deviation

Front 37

skew deviation

Back 37

vertical disparity in the position of the eyes of supranuclear origin; relatively constant in all positions of gaze (unlike trochlear palsy)

Front 38

what can cause skew deviation

Back 38

lesions of cerebellum, brainstem, or inner ear

Front 39

causes of head tilt

Back 39

trochlear palsy, cerebellar lesions, meningitis, incipient tonsillar herniation, and torticollis

Front 40

diplopia in abducens nerve lesions

Back 40

horizontal diplopia; sometimes estropia present

Front 41

what is abducens palsy an important early sign of and why

Back 41

supratentorial or infratentorial tumors, pseudotumor cerebri, hydrocephalus, and other intracranial lesions; due to susceptibility of injury from downward traction caused by elevated ICP

Front 42

gaze palsy

Back 42

movements of both eyes in one direction are decreased

Front 43

causes of horizontal diplopia

Back 43

abducens palsy, myasthenia gravis, disorders of extraocular muscles

Front 44

location of edinger-westphal nuclei

Back 44

just dorsal and anterior to the oculomotor nuclei near midline

Front 45

where do preganglionic parasympathetic fibers travel bilaterally from the edinger-westphal nuclei to

Back 45

go via oculomotor nerves to reach ciliary ganglia in orbit

Front 46

3 components of accomodation response

Back 46

pupillary constriction, accomodation of lens ciliary muscle, and convergence of the eyes

Front 47

what occurs when the ciliary muscle contracts

Back 47

causes suspensory ligament to relax producing a rounder, more convex lens shape

Front 48

where does the descending sympathetic pathway activate preganglionic sympathetic neurons involved with pupil dilation

Back 48

intermediolateral cell column of upper thoracic cord

Front 49

how do preganglionic sympathetic neurons of pupil dilation get to pupil

Back 49

exit spinal cord via ventral roots of T1-2 and join paravetebral sympathetic vhain via white rami communicantes; synapse in superior cervical ganglion and ascend through carotid plexus along wals of internal carotid artery

Front 50

anisocoria

Back 50

pupillary asymmetry

Front 51

classic horner's syndrome

Back 51

ptosis, miosis, and anhidrosis along with several other minor abnormalities; due to disruption of sympathetic pathways

Front 52

anisocoria in oculomotor vs horner's

Back 52

horner's more obvious in dark, oculomotor more in ambient light

Front 53

horners and light reflexes

Back 53

still has direct and consensual response to light; dilation lag relative to normal pupil when light removed

Front 54

ciliospinal reflex

Back 54

painful pinch to neck activates sympathetic outflow, causing pupillary dilation on normal side but not on side with Horner's syndrome

Front 55

anhidrosis

Back 55

decreased sweating of ipsilateral face and neck in horner's; skin feels smoother due to decreased moisture

Front 56

posible locations for Horner's syndrome lesions

Back 56

1) lateral brainstem 2) spinal cord 3) T1-2 roots 4) sympathetic chain 5) carotid plexus 6) cavernous sinus 7) orbit

Front 57

pontine pupils

Back 57

both pupils and small but reactive to light; probably caused by bilateral disruption of descending sympathetic pathways

Front 58

Afferent Pupillary Defect (Marcus Gunn Pupil)

Back 58

direct response to light in affected eye is decreased or absent while consensual response of affected eye in opposite eye is normal

Front 59

where are lesions located in Marcus Gunn pupil

Back 59

lesions in front of optic chiasm

Front 60

hippus

Back 60

normal brief oscillation of pupil size that sometimes occurs in response to light

Front 61

opiates and pupils

Back 61

bilateral pinpoint pupils

Front 62

barbituate OD pupils

Back 62

bilateral small pupils, mimickng pontine lesions

Front 63

anticholinergic agents affecting muscarinic receptors (atropine or scopolamine) and pupils

Back 63

dilated pupils

Front 64

pilocarpine eyedrops are useful when what is suspected

Back 64

anticholinergic agents; cause pupillary constriction in parasympathetic lesions, but can't overcome pharm muscarinic blockade

Front 65

light-near dissociation

Back 65

pupils constrict much less in response to light than to accomodation

Front 66

example of light-near dissociation

Back 66

Argyll Robertson pupil associated with neurosyphilis (pupils small and irregular as well); diabetes, Adie's myotonic pupil, Parinaud's syndrome

Front 67

Adie's myotonic pupil

Back 67

degeneration of the ciliary ganglion or postganglionic parasympathetic neurons resulting in mid-dilated pupil that reacts poorly to light

Front 68

Midbrain Corectopia

Back 68

pupil assumes irregular, odd-center shape; rare

Front 69

muscle of eye closure

Back 69

orbicularis oculi (CN VII)

Front 70

ptosis vs facial muscle weakness

Back 70

ptosis upper lid comes down further over iris in affected eye; facial weakness palpebral fissure widened due to sagging of lower lid

Front 71

what does cavernous sinus drain

Back 71

eye, superficial cortex

Front 72

what layer does the cavernous sinus lye

Back 72

btwn periosteal and dural layers of dura mater-like the other venous sinuses

Front 73

nerve closest to carotid in cavernous sinus

Back 73

abducens (III, IV, and V1 also in sinus)

Front 74

what nerve skirts the lower portion of the cavernous sinus and often runs through it for a short distance

Back 74

V2-exits via forament rotundum

Front 75

orbital apex

Back 75

region where nearly all nerves, arteries, veins or orbit converge b4 communicating with intracranial cavity via optic canal and superior orbital fissure

Front 76

orbital apex vs cavernous sinus lesions

Back 76

same deficits, but more likely to involve CN II also

Front 77

saccades

Back 77

rapid eye movements reaching velocities up to 700 degrees per second; fxn to bring tagets of interest into field of view

Front 78

vision during saccade

Back 78

transiently suppressed

Front 79

smooth pursuit eye movements

Back 79

not under voluntary control; reach velocities of 100 degrees/s; allow stable viewing of moving objects

Front 80

vergence eye movements

Back 80

maintain fused fixation by both eyes as targets toward or away from viewer; velocity ~20 degrees/s

Front 81

reflex eye movement examples

Back 81

optokinetic nystagmus and vestibulo-ocular reflex

Front 82

nystagmus

Back 82

rhythmic form of reflex eye movements composed of slow eye movements in one direction interrupted repeatedly by fast saccadelike eye movements in opposite direction

Front 83

what interconnects the oculomotor, trochlear, abducens, and vestibular nuclei

Back 83

medial longitudinal fasciculus (MLF)

Front 84

abducens nucleus fxns as

Back 84

horizontal gaze center controlling horizontal movement of both eyes in direction ipsilateral to side of nucleus (some fibers project to ipsilateral lateral rectus and some to contralateral oculomotor nucleus)

Front 85

paramedian pontine reticular formation (PPRF)

Back 85

horizontal gaze center; provides input from cortex and other pathways to abducens nucleus

Front 86

lesion of abducens nucleus causes

Back 86

ipsilateral gaze palsy involving both eyes because of connections through MLF

Front 87

lesions of MLF and horizontal eye movements

Back 87

interrupt input to medial rectus; eye ipsilateral to lesion does not fully adduct on attempted horizontal gaze, also nystagmus of opposite eye (unknown reason)

Front 88

internuclear ophthalmoplegia (INO)

Back 88

classic neurologic syndrome produced by MLF lesion

Front 89

where are brainstem centers for vertical eye movements

Back 89

rostral midbrain reticular formation and pretectal area; ventral portion=downgaze and dorsal = upgaze

Front 90

nucleus for downgaze

Back 90

rostral interstitial nucleus of MLF; also Darkschewitsch and interstitial nucleus of Cajal

Front 91

what controls vergence

Back 91

descending inputs from visual pathways in occipital and parietal cortex

Front 92

Parinaud's syndrome cause

Back 92

constellation of eye abnormalities usually seen with lesions compressing the dorsal midbrain and pretectal area

Front 93

Parinaud's syndrome 4 components

Back 93

1) impairment of vertical gaze, especially upgaze 2) large, irregular pupils that don't react to light 3) eyelid abnormalities 4) impaired convergence and sometimes convergence-retraction nystagmus

Front 94

most common cause of Parinaud's

Back 94

pineal region tumors and hydrocephalus

Front 95

hydrocephalus and eyes in kids

Back 95

bilateral setting-sun sign; eyes deviate inward due to bilateral 6th verve palsies and downward due to Parinaud's syndrome

Front 96

frontal eye fields

Back 96

generate saccades in contralateral direction via connections to contralateral PPRF

Front 97

parieto-occipito-temporal cortex and eye movements

Back 97

smooth pursuit in ipsilateral direction via connections with vestibular nuclei, cerebellym, and PPRF

Front 98

optokinetic nystagmus (OKN) is elicited how

Back 98

moving a thick ribbon with vertical stripes horizontally in front of the eyes; eyes alternate btwn smooth persuit and saccades

Front 99

slow phase of OKN is mediated by

Back 99

ipsilateral posterior cortex with connections to vestibular nuclei and flocculonodular lobe of cerebellum projecting to PPRF and abducens nuclei

Front 100

fast phase of OKN is mediated by

Back 100

frontal eye fields projecting to contralateral PPRF

Front 101

vestibulo-ocular reflex (VOR)

Back 101

stabilizes eyes on the visual image during head and body movements

Front 102

how is VOR tested

Back 102

oculocephalic maneuver or cold water calorics