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74 Cards in this Set

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  • Back
Which muscles cause the eyes to move within the orbits?
Extraocular
Which muscles control pupillary size and accommodation?
Internal ocular muscles
The nuclear and infranuclear pathways involved which structures?
brainstem nuclei of CN III, IV, and VI, the peripheral nerves of these nuceli, and eye movement muscles.
Supranuclear pathways involve which structures?
brainstem and forebrain circuits that control eye movements via connections with CN III, IV, and VI nuclei.
Which six extraocular muscles are innervated by CN III, IV, VI?
1.lateral rectus (abduction)
2.medial rectus (adduction)
3. superior rectus (elevation and intorsion)
4. inferior rectus (depression and extorsion)
5. superior oblique (depression and intorsion)
6. inferior oblique (elevation and extorsion)
The ___ nerve innervates the extraocular muscles: medial rectus, superior rectus, inferior rectus, inferior oblique
Oculomotor nerve (CN III)
The ___ nerve innervates the superior oblique muscle.
Trochlear nerve (CN IV)
The ___ nerve innervates the lateral rectus.
Abducens nerve (CN VI)
The parasympathetic fibers controlling pupil constriction are vulnerable to compression by aneurysms particulalry originating from _______.
Posterior communicating artery
Trochlear nerves are the only nerves to exit the brainstem dorsally in a crossed fashion. They are susceptible to compression from _________ and ________from head trauma.
cerebellar tumors; shear injury
Abducens nerves are susceptible to downward traction injury produced by____.
elevated intracranial pressure
Mechanical problems, extraocular muscle dysfunction, neuromuscular junction dysfunction, and disorders of CN III, IV, and VI are primary causes of _____.
diplopia (double vision)
Monocular diplopia or polyopia (3 or more images) can be caused by _____ disease, disorders of _____ cortex, or _______, but NOT by _________.
ophthalmological; visual; psychiatric conditions; eye movement abnormality
_________ gaze results from extraocular muscle dysfunction and causes _________.
Dysconjugate; diplopia
Abnormal lateral deviation of one eye is called ___.
Exotropia
Abnormal medial deviation of one eye is called _____.
Esotropia
Abnormal vertical deviation of one eye is called_____.
Hypertropia
Mild weakness present with only one coveed eye is called _____.
Phoria
Oculomotor Palsy involving complete disruption of CN III is characterized by:
1. paralysis of all extraocular muscles except lateral rectus and superior oblique
2. eye lies in "down and out" position
3. upper lid is closed b/c of levator palpebrae superior paralysis
4. pupil is dilated and responsive to light
5 Common causes of oculomotor palsy include:
diabetic neuropathy; head trauma from shearing; nerve compression from intracranial aneurysms (e.g Pcomm); nerve compression from medial temporal lobe herniation; and opthalmoplegic migraine in children
Third nerve palsy raises high suspicion for _______.
aneurysm; can cause a painful oculomotor palsy involving pupil.
______________ involving CN IV produces depression and intorsion resulting in _____ diplopia.
Trochlear palsy; vertical
CN IV palsy is confirmed by what four steps?
Bielschowsky 3 step test plus one step:
1.hypertropia of affected eye
2.worsening vertical diplopia when affected eye looks nasally
3.improving vertical diplopia with head tilt away from eye
4.vertical diplopia worsens with downgaze
CN IV is most commonly injured cranial nerve in ____.
head trauma b/c of its susceptibility to shear
Four other casues of vertical diplopia include:
1. extraocular muscle disorders
2.myasthenia gravis
3.lesions of the superior division of CNIII affecting superior rectus
4.skew deviation (vertical disparity in eye position of supranuclear origin)
Abducens palsy of the ____cranial nerve produces ____ diplopia which can also be caused by______and disorders of extraoclar muscles from ________, _____, ________, or ________.
VI; horizontal; myasthenia gravis; thyroid disease, tumors,inflammation or orbital trauma.
CN VI is susceptible to injury from downward traction caused by ____.
Intracranial Pressure
Abducens palsy is an early sign of what conditions?
1.supratentorial or infratentorial tumors
2.psudotumor cerebri
3.hydrocephalus
4.other intracranial lesions
CN VI lesions often affect CN___fibers, cuasing _____facial weakness.
VII; ipsilateral
Pupils are controlled by which 2 pathways?
1. parasympathetic
2. sympathetic
Parasympathetic pathways involving pupil constriction are:
1.light enters eye
2.retinal ganglion cells project to both optic tracts
3.brachium of superior colliculus
4.past LGN
5.pretectal area
6.Edinger-Westphal nucleus
7.ciliary ganglia via oculomotor nerves
8.pupillary constrictor muscles
A light shone in one eye causes a ____ response in the same eye and a ____response in the other eye because information crosses_____ at multiple levels.
direct; concensual; bilaterally
The ____ response is another pathway for bilateral pupillary constriction and occurs when a visual object moves from __ to __.
Acommodation; far to near
Characteristics of the accommodation response include:
1.pupillary constriction
2.accommodation of the lens ciliary muscle
3.convergence of the eyes
Pupillary asymmetry is called___.
anisocoria
Oculomotor nerve lesions cause what pupillary abnormalities?
1.impaired constriction causing unilateral dilated pupil
2.very large pupil ("blow pupil") when lesion is complete
Horner's Syndrome is characterized by what triad of symptoms?
1.ptosis (upper eyelid droop)
2.miosis(decreased pupillary size)
3.anhidrosis (decreased sweating of the ipsilateral face & neck)
Horner's Syndrome is caused by________.
loss of sympathetic innervation to the pupillary dilator muscle, causing impaired dilation of the pupil
lesions anywhere in the ____ pathway can cause Horner's Syndrome.
sympathetic
Afferent pupillary defect is also known as _____.
Marcus Gunn Pupil
Afferent pupillary defect is characterized by________and _____.
direct response to light in affected eye is decreased/absent; consensual response of affected eye to light in opposite eye is normal.
Causes of afferent pupillary defect include:
decreased sensitivity of affected eye to light from lesions of the optic nerve, retina, or eye
Slight pupillary asymmetry (<.6mm) in 20% of the general population that may vary periodically is called____.
benign (essential, physiological) anisocoria
Pharmacological miosis and mydriasis can be caused by opiates which result in_____; barbituate overdose which causes____;and anticholinergic agents that cause_____.
bilateral pinpoint pupils; bilateral small pupils; dilated pupils
Midbrain Corectopia refers to lesions of the midbrain that can cause _______.
pupillary abnormality where pupil assumes an irregular offcenter shape (rare)
The following are all potential causes of ______:
-Horner's syndrome
-Oculomotor nerve palsy
-myasthenia gravis
-redundant sin folds from aging
-nondominant parietal lobe lesion
-dorsal lesions of the oculomotor nuclei affecting the central caudate nucleus
-voluntary eye closure
Ptosis (drroping of the eyelid)
Which muscles and cranial nerves are associated with eye opening?
levator palpebrae superior (CN III), Muller's smooth muscle in upper eye lid (sympathetics); frontalis muscle (CN VIII)
Which muscle and cranial nerve is involved with eye closure?
orbicularis oculi muscle (CN VII)
region where almost all nerves, arteries, and veins of the orbit converge before communicating with the intracranial cavity via the optic canal and superior orbital fissure
orbital apex
cavernous sinus syndrome, characterized by total ophthalmoplegia and a fixed, dilated pupil, involves which cranial nerves?
CN III, IV,VI, V1
Which type of lesion produced similar symptoms as complete lesion of the cavernous sinus, but may also involve CN II, resulting in visual loss?
orbial apex lesion
supranuclear circuits control which types of horizontal, vertical, and vergence eye movements?
saccades (rapid eye movementsthat bring targets into field of view--only one that can be performed easily voluntarily)
smoot pursuit (slower eye movements, not under voluntary control, allow stable viewing of moving objects)
vergence (slower eye movements that maintain fused fixation by both eyes as targets move toward or away from viewer)
reflex eye movements (include optokinetic nystagmus and vestibulo-ocular reflex)
rhythmic form of reflex eye movements made up of slow eye movements in one direction and interrupted by fast saccade like eye movements in opposite direction is called _____.
nystagmus
important horizontal gaze center that provides input from the cortex and other pathways to the abducens nucleus is called _____.
paramediuan pontine reticular formation (PPRF)
Name and describe five lesions affecting horizontal gaze.
1. abducens nerve (impaired abduction of ipsilateral eye)
2. abducens nucleus (ipsilateral lateral gaze palsy in both eyes)
3. PPRF (ipsilateral lateral gaze palsy)
4.MLF (internuclear ophtalmoplegia-INO: eye ipsilateral to lesion does not fully adduct on attempted horizontal gaze, nystagmus in opposite eye; side of INO is same as side of MLF lesion)
5.MLF and adjacent abducens nucleus or PPRF (one and a half syndrome: ipsilateral INO plus ipsilateral lateral gaze palsy)
MS plaques, pontine infarcts, MLF neoplasms are common causes of____.
MLF lesions which cause INO (internuclear ophthalmoplegia)
Large pontine lesions disrupt bilateral corticospinal tracts and abducens nuceli, eliminating body movements and horizontal eye movements are chacteristics of which syndrome? Sometimes vertical eye movement centers in the midbrain are spared, allowing communication entirely through vertical eye movements.
Locked in syndrome.
________ eye movements are generated by superior and inferior rectus and superior and inferior oblique muscles; brainstem controlling centers are located in the ____midbrain_____ and _____ area. _____portion mediates downgaze; ____ region mediates upgaze.
vertical; rostral, reticular formation; ventral; dorsal
Parinaud's syndrome, caused by pineal region tumors and hydrocephalus, is composed of what four components?
1. Impaired vertical gaze (especially upgaze)
2. large, irregular pupils with light-near dissociation
3. eyelid abnormalities
4. impaired convergence and sometimes convergence-retraction nystagmus
Descending cortical pathways go directly to the _____centers for horizontal, vertical or vergence eye movements or via relays in the _____ ____ _____.
brainstem; midbrain superior colliculi
Frontal eye fields in the forebrain also control eye movements. They lie at the junction between ____ ___ ___ and ___ ___; overlap ___ and ___ cortices which reflect roles in __ ___ __and ____ ___; generate saccades in ___ diretion via the ____.
superior frontal sulcus, precentral sulcus; premotor and prefrontal; eye movement control, selective attention; contralateral, PPRF.
___-___-____ cortex is responsible for smooth pursuit movements in the ____ direction via connections with the vestibular nuclei, cerebellum, and PPRF.
parieto-occipital-temporal, ipsilateral
cortical descending control of eye movements is heavily influenced by ____ inputs from the primary ___ cortex and ___association cortex.
visual
Subcortical ___ ____ also modulate eye movements.
basal ganglia
Cerebral hemisphere lesions normally impair eye movements in the ____ direction, causing a gaze preference ____ the side of the lesion;
contralateral, toward
cerebral hemisphere lesions are normally accompanied by weakness ____ to the cortical lesion, so the eyes look ___ the side of weakness
contralateral, away from
Wrong way eyes look ____ the side of weakness. Possible causes include: ___ in cortex, __lesions (thalamic hemorrhage) usually accompanied by deep coma, and ___.
toward; seizure, large, lesions of the pontine basis and tegmentum
Symptoms of oculomotor nerve palsy (CNIII) secondary to aneurysum include:
left frontal and retro-orbital headaches, hx of left eye drifting to the left, diplopia with image from left eye above and to the right of image from the right eye; diplopia worse when looking to right; left eye with limited but not absent upgaze, downgaze, and adduction, and ptosis, and fixed dilated pupil
Hx of diabetes, horizontal diplopia worse on left gaze, and incomplete abduction of left eye can be caused by what?
isolated abducens nerve palsy caused by microvascular disease
Symptoms of right hypertropia and vertical diplopia worse with downward and leftward gaze and worse with rightward head tilt can be associated with what dx?
isolated right trochlear nerve palsy caused by idiopathy neuropathy of likely microvacular origin
Name possible differental diagnoses of the follwing symptoms:on right gaze, left eye pain, limited adduction, horizontal diplopia with right image disappearing when left eye covered; on left gaze mild horizontal diplopia with left image disappearing when left eye covered; pain and erythema of left orbital conjunctiva
infectious, inflammatory, neoplastic disorder, orbital myositis (orbital pseudotumor: uncommon inflammatory condition of the extraocular muscles
Symptoms of Horner's syndrome caused by TBI or carotid dissection may include___?
left ptosis, small reactive left pupil with decreased ciliospinal reflex, decreased left facial sweating
Lethargy, rightward gaze preference, inability to move either eye past midline toward the left; right face, arm, and leg weakness; upgoing plantar response to the right can be caused by___ or ___.
Wrong way eyes; infarct of the left pons
Headaches, large pupils with minimal reaction to light but preserved reaction to accommodation (light-near-dissociation_; inabilty to look upward; lid reaction and convergence-retraction nystagmus can be caused by____.
Parinaud's syndrome from pineal region tumor compressing the dorsal midbrain