Control of Eye Movements Flashcards by Deleted Deleted

Which of the following correctly defines smooth pursuit gaze control system?

A. Rapid eye movement that brings image of object onto the fovea

B. Keeps a moving object centered on the fovea

C. Holds image stead on the fovea during head movements

D. Keeps image on fovea when the object is moved near or far away

Keeps a moving object centered on the fovea

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Which of the following correctly defines saccadic gaze control system

A. Rapid eye movement that brings image of object onto the fovea

B. Keeps a moving object centered on the fovea

C. Holds image stead on the fovea during head movements

D. Keeps image on fovea when the object is moved near or far away

Rapid eye movement that brings image of object onto the fovea

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Which of the following correctly defines the vestibular-ocular gaze control system?

A. Rapid eye movement that brings image of object onto the fovea

B. Keeps a moving object centered on the fovea

C. Holds image stead on the fovea during head movements

D. Keeps image on fovea when the object is moved near or far away

Holds image stead on the fovea during head movements

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Which of the following correctly defines the vergence gaze control system?

A. Rapid eye movement that brings image of object onto the fovea

B. Keeps a moving object centered on the fovea

C. Holds image stead on the fovea during head movements

D. Keeps image on fovea when the object is moved near or far away

Keeps image on fovea when the object is moved near or far away

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All of the following supranuclear gaze control systems are conjugate movements, EXCEPT for which of the following that is disconjugate?

A. Saccadic

B. Smooth pursuit

C. Vestibular-ocular

D. Vergence

Vergence

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The __________ is involved with voluntary eye movement, while the __________ is involved with reflexive eye movement

A. Medial Longitudinal Fasciculus; Paramedian Pontine reticular formation (PPFT)

B. Frontal eye field; Medial Longitudinal Fasciculus

C. Inferior Colliculus; Superior Colliculus

D. Frontal eye field; Superior Colliculus

Frontal eye field; Superior Colliculus

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The sacaddic system for horizontal movement involves what two cranial nerves?

CN III

CN VI

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Describe the pathway of activity when the right frontal eye field is stimulated in the Saccadic system for Horizontal eye movement?

What direction will we be looking in when the right frontal eye field is stimulated?

Right frontal eye field is stimulated and sends its axons to the Paramedian Pontine Reticular Formation (PPRF)

Secondary neurons leave the PPRF and synapse in the contralateral Abducens Nucleus

2 sets of Tertiary neurons leave from the contralateral abducens nucleus.

The contralateral third order neurons synapse onto the latearl rectus muscle of the left eye.

The ipsilaterally traveling neuron leaves the abducens nucelus passes through the Medial Longitudinal Fasciculus, and synapses in the Occulomotor nucleus

From the occulomotor nucleus the neuron goes to the ipsilateral medial rectus muscle

We look left

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What two cranial nerves are utilized in the vertical saccadic system?

CN III

CN IV (trochlear)

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Which of the following is another name for the vertical gaze system that is utilized in the saccadic system, and can be impinged upon by a pineal tumor?

A. Dorsal Nucleus of Clark

B. Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus

C. Medial Lemniscus

D. Superior colliculus

Rostral Interstitial Nucleus of the Medial Longitudinal Fasciculus

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A lesion of the PPRF will cause which of the following?

A. Contralateral damage

B. Ipsilateral damage

Ipsilateral damage

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The Superior Colliculus as well as what two other areas contribute to the reflex saccadic eye movements?

Parietal and Supplementary eye frields

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A Horizontal Gaze palsy is caused by destruction of what structure?

Abducens Nucleus

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Internucleus Opthalmopeligia is caused by destruction of what structure?

What action can no longer be performed?

MLF

Adduction in either eye

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The Brainstem has control cells for saccadic movements that involv 3 neuron types. Answering the following questions will help you ot understand there goal. Note that there are technically seperate control systems for horizontal and vertical movements.

What type of neurons are needed to move the eyes towards the target?

What type of neurons are needed to help us lock on to the target or fix our gaze?

What type of neuron is needed to inhibit the first neuron discussed, so that no further movement occurs?

Burst neurons: get to target

Tonic neurons: lock on to target

Pause neurons: hold still

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Burst cells of the horizontal saccadic system are found in which of the following locations?

A. Pontine paramedian Reticular formation

B. Nucleus prepositus hypoglossi

C. Interstitial nucleus of Cajal

D. Rostral interstitial nucleus of MLF

E. Raphe Nuclei

Pontine paramedian Reticular formation

Burst cells of the vertical saccadic system are found in which of the following locations?

A. Pontine paramedian Reticular formation

B. Nucleus prepositus hypoglossi

C. Interstitial nucleus of Cajal

D. Rostral interstitial nucleus of MLF

E. Raphe Nuclei

Rostral interstitial nucleus of MLF

Tonic cells of the vertical saccadic system are found in which of the following locations?

A. Pontine paramedian Reticular formation

B. Nucleus prepositus hypoglossi

C. Interstitial nucleus of Cajal

D. Rostral interstitial nucleus of MLF

E. Raphe Nuclei

Interstitial nucleus of Cajal

Tonic cells of the horizontal saccadic system are found in which of the following locations?

A. Pontine paramedian Reticular formation

B. Nucleus prepositus hypoglossi

C. Interstitial nucleus of Cajal

D. Rostral interstitial nucleus of MLF

E. Raphe Nuclei

Nucleus prepositus hypoglossi

While there are seperate control systems for horizontal and vertical saccade movements, pause cells of BOTH the saccadic systems are found in which of the following locations?

A. Pontine paramedian Reticular formation

B. Nucleus prepositus hypoglossi

C. Interstitial nucleus of Cajal

D. Rostral interstitial nucleus of MLF

E. Raphe Nuclei

Raphe Nuclei

Look at this and appreciate

Cool

A destructive lesion of the frontal gaze center results in what presentation?

Transient conjugate eye devation TOWARD the side of the lesion, with difficulty looking away from the lesion

when you see a train wreck (destruction) you can’t look away, you look at the destruction

Seizure activity in the frontal gaze center results in what presentation?

Eyes look away from the firing gaze center

Annoying things cause you to roll your eyes and look away

Smooth pursuit lee[s moving objects centered on fovea and stimulates what area of the brain?

Parieto-occipital junction (Broadmann’s area 19)

Describe the neuron pathway of the smooth pursuit, when perfoming horizontal gaze. Assume the right parieto-occipital junction (Broadman's 19) was stimulated

Right parieto-occipital jxn was stimulated and sends neurons to the Pontine nuclei on the ipsilateral side Neurons leave the pons and enter the Vestibulocerebellum Neurons leave the Vestibulocerebellum to synapse in the Vestibular Nuclei Neurons leave the vestibular nuclei to synapse in the ipsilateral abducens nucleus 2 sets of neurons will leave the Abducens nucleus One set of neurons will pass through the MLF and synapse in the left occulomotor nucleus and then send neurons to the medial rectus muscle in the left eye Other set of neurons will leave the Abducens nucleus and innervate the right lateral rectus muscle Right Parieto-occipital junction makes us look right *NOTE: Try not to overly complicate this pathway, Know that stimulating the right parieto-occipital junction makes us look right, and from there know what eye muscles in the R/L eye need to work. "ex. if left parieto-occipital jxn is stimulated, we know we'll look left. To look left we have to stimulate the Left Lateral Rectus and the Right Medial Rectus"*

T/F: Optokinetic holds images of the target steady on the retina while the head is moving. This requires an intact parietooccipital eye field, and involves optokinetic nystagmus in the opposite direction

True

Why do we send some fibers to the inferior olive?

Correct error movements

A lesion of the parietal lobe will cause loss of smooth pursuit movements in what direction in relation to the lesion? What will we see in regards to optokinetic nystagmus in relation to the lesion?

Loss of movement TOWARD the side of the lesion No OKN toward the side of the damaged lobe *ex. while pulling optokinetic tape to the right, we notice OKN, but when pulling the tape to the left we do NOT notice OKN, therefore the lesion is on the left side*

The Vestibular-occular system holds the image steady on the fovea during head movements and utilizes the same vestibulo-ocular pathway Dr. Dennis described in the last lecture. See those flashcards for a better understanding

Got it

T/F: In a comatose patient with dysfunction at the level of the brainstem, Doll's eyes and ice water calorics will be absent

True

Internucleuar opthalmoplegia results from a lesion in what structure? Which eye will we see abduction nystagmus in in relation to the lesion?

MLF (pons and midbrain) Contralateral eye

Appreciate this

Appreciate it again

Put the following terms in order, and explain the rational Pupillary contriction Convergence Accomidations

1. Convergence: put image on fovea 2. Pupillary constriction: improve optical performance 3. Accommodation: lens thickens to focus the image better

What is the pathway of the near reflex? Why are we able to still perform the near reflex when the MLF is damaged?

1. Visual tract via optic nerve goes through the optic chiasm to the LGN 2. Visual cortex 3. Superior Colliculus or pretectal area or both 4. CN 3 nucleus and edinger westphal nucleus We bypass the MLF

T/F: In PTs with progressive neurosyphylis the light reflex is absent, but the pupils will constrict in near reflex testing

True NOTE: also called Argyll-Robertson Pupil

Stimulation of the right paramedian pontine reticular formation nuclei causes which of the following? A. Both eyes to move left B. Both eye to move right C. Left eye to move left D. Left eye to move right E. Right eye to move left F. Right eye to move right

Both eye to move right *The PPRF receives input from the contralateral cortex as the interneuron connection to the abducens nucleus, which also contrains the MLF, which is why both eyes saccade to the side of PPRF stimulation*

A 45 yo tree trimmer complains to his physician that he is tired all of the time and that he has had recent trouble looking up into the tres to accomplish his work. Upon an eye exam you notice that when asked to look upward, his eyes remain at midlevel yet all other eye movements are normal. What is the most reasonable explanation for these findings? A. Damage to the flocculonodular lobe B. Damage to the paramedian pontine reticular formation C. Damage to the superior oblique in both eyes D. Pineal tumor E. Pituitary tumor

D. Pineal tumor *The pineal gland is located right above the superior colliculus and can undergo hypertrophy resulting in pressure and inactivation of the interneurons. This results in the loos of upward saccads. Pituitary tumors can secrete large amounts of melatonin, causing drowsiness. Pituitary tumor often results in heteronymous visual field deficits*

A patient was seen in the ED after the sudden onset of severe headache and dizziness. Squirting warm or cool water into either ear caused nystagmus of notmal amplitude and direction. However, when the patient tried to suppress the nystagmus by starting at a sign on the wall, she was unable to do so. The most liekly site of damafe was the A. Basal ganglia B. Cerebellum C. Occipital Lobes

B. Cerebellum *The floculus plays a critical role in VOR suppression and adaption*