Neuro Fns Lect #24

Front 1

What are conjugate eye movements?

Back 1

Both eyes move in the same direction

Front 2

What are vergence eye movements?

Back 2

Two eyes move in opposite directions

Front 3

Fast movements used by the eye to aquire new visual targets are called what?

Back 3

saccades

Front 4

Slower movments used to keep an image focused on the fovea are called what?

Back 4

Smooth eye movements

Front 5

A pupil moving laterally is (adduction,abduction)?

Back 5

ABDuction

Front 6

When the top of the eye moves medially, it is called (extorsion, intorsion)?

Back 6

intorsion

Front 7

This is the condition in which the two eyes are NOT directed at the same point in space?

Back 7

Strabismus

Front 8

This is the perception of two offset images of the visual field, usually caused by strabismus?

Back 8

Diplopia

Front 9

Oscillatory conjugate eye movements with a smooth component AND a saccadic component is termed?

Back 9

Nystagmus

Front 10

How is nystagmus named, in relation to what direction?

Back 10

In the direction of the fast eye movement

Front 11

What are the three extraocular GSE nuclei ?

Back 11

Nucs 3,4,6

Front 12

True/False CN 3,4,6 have components of both efferent and afferent fibers?

Back 12

False, exclusively efferent

Front 13

Where does the abducens nucleus lie?

Back 13

in the floor of the 4th ventricle within the genu of CN VII

Front 14

What are the two populations of neurons found in the abducens nucleus?

Back 14

GSE neurons and Abducens Internuclear Neurons

Front 15

What do the GSE neurons of the abducens nucleus eventually innervate?

Back 15

ipsilateral lateral rectus

Front 16

Where do fibers of the abducens internuclear neurons go?

Back 16

Ascend within the Contralateral MLF to synapse in the oculomotor complex on the LMN that innervate the medial rectus

Front 17

The two populations of neurons within the abducens nucleus work together to produce what kind of conjugate eye movements?

Back 17

Lateral gaze movements

Front 18

Are abducens internuclear neurons involved in activation of the medial rectus during convergence of the eyes?

Back 18

NO

Front 19

Because of its long intracranial course, which includes ascending the clivus, entering the cavernous sinus, and going through the superior orbital fissure to enter the orbit, IT is the most commonly injured CN?

Back 19

Abducens nerve

Front 20

A unilateral lesion of the abducens nerve produces paralysis of which muscle?

Back 20

ipsilateral lateral rectus

Front 21

The affected eye, in a unilateral lesion of CN 6, is in what position

Back 21

Adducted

Front 22

What kind of diplopia is produced upon lesion of the abducens nerve?

Back 22

horizontal diplopia

Front 23

The horizontal diplopia produced on lesion of CN 6 is made worse during what ?

Back 23

Attempted lateral gaze to the side of the lesion

Front 24

paralysis of lateral gaze to the right side can be caused by what?

Back 24

lesion of R abducens nucleus

Front 25

In lesions of the abducens nucleus, where are both eyes deviated to?

Back 25

The side opposite the lesion

Front 26

Is there any horizontal diplopia in patients with unilateral lesions of the abducens nucleus?

Back 26

No

Front 27

This is often the presenting disturbance in multiple sclerosis and strokes?

Back 27

internuclear opthalmoplegia (MLF syndrome)

Front 28

What is destroyed in internuclear opthalmoplegia?

Back 28

axons of abducens internuclear neurons projecting from the contralateral abducens nucleus

Front 29

In MLF syndrome, there is paresis of ocular adduction on attempted lateral gaze to the side (of the lesion, opposite to the lesion)?

Back 29

Opposite the lesion

Front 30

Monoocular horizontal nystagmus is seen in (affected eye or opposite eye) of patients with MLF syndrome when they attempt to lateral gaze to the side opposite the lesion?

Back 30

Opposite eye

Front 31

The superior oblique muscle is innervated by axons found in which nucleus?

Back 31

contralateral trochlear nucleus

Front 32

In what position of the eye is the superior oblique muscle a pure depressor?

Back 32

when it is adducted

Front 33

What is the main depressor of the eye during adduction?

Back 33

Superior Oblique muscle

Front 34

A patient has a right lesion in the trochlear nerve and is facing you, how is his right eye positioned?

Back 34

elevated, adducted, extorted (superior oblique depresses, abducts, and intorts)

Front 35

When a patient with a right lesion of the trochlear nerve gazes to the left, what kind of diplopia will he have?

Back 35

vertical diplopia (his R eye will be elevated higher than the left)

Front 36

In a patient with R trochlear nerve lesion, how is maximum vertical diplopia achieved?

Back 36

looking to the left AND down

Front 37

what kind of diplopia is seen when a patient with a lesion in the trochlear nerve is looking forward?

Back 37

oblique diplopia

Front 38

What do children with unilateral lesions of the trochlear nerve do in order to compensate?

Back 38

tilt their head to the side opposite the lesion

Front 39

Are unilateral lesions of the trochlear nucleus common?

Back 39

Very rare

Front 40

Unilateral lesions of the trochlear nucleus produce clinical signs on the (ipsilateral or contralateral eye)?

Back 40

contralateral

Front 41

What are the five muslces innervated by axons from the somatic motor neurons of the oculomotor complex?

Back 41

inferior and medial rectus, inferior oblique, superior rectus, levator palpebrae

Front 42

Edinger westphal nucleus receive bilateral afferents from what?

Back 42

pretectal olivary nucleus

Front 43

What nerve do the axons of the edinger-westphal nucleus course in?

Back 43

CN III

Front 44

where do the axons of the edinger-westphal nucleus synapse?

Back 44

ciliary ganglion

Front 45

Postganglionic parasympathetics from the ciliary ganglion form what nerves and innervate which muscles?

Back 45

short ciliary nerves and ciliary muslces and sphincter palpebrae

Front 46

In a unilateral lesion of CN III, what position is the ipsilateral eye in?

Back 46

extreme abduction and downward position (virtually immobile)

Front 47

A patient with a lesion in the right oculomotor nerve is looking at you, what do you see?

Back 47

R eyelid completely shut (ptosis)

Front 48

How do the pupils look in a patient with a unilateral lesion of the oculomotor nerve?

Back 48

ipsilateral pupil is completely dilated (mydriasis); Anisocoria (pupils of unequal size)

Front 49

Are the pupillary light reflex present in the affected eye of a patient with a unilateral lesion in the oculomotor?

Back 49

NO (both consensual and direct)

Front 50

Is the accomodation reflex present in a patient with unilateral lesion of CN III?

Back 50

It is absent in the affected eye

Front 51

This nucles mediates the VOR, which keeps the eyes fixed on a stationary point in space while the head moves?

Back 51

vestibular nuclei

Front 52

Rotation of the head to the right causes which hair cells to depolarize (Right or Left)?

Back 52

Right

Front 53

Rotation of the head to the left causes which hair cells to hyperpolarize (right or left)?

Back 53

right

Front 54

Where do axons of the vestibular nuclei project to?

Back 54

contralateral abducens nuclei

Front 55

Where do the axons of the LMNs of the abducens project to?

Back 55

ipsilateral lateral rectus

Front 56

Where do the internuclear neurons of the abducens project to?

Back 56

contralateral oculomotor complex (via the contralateral MLF)

Front 57

During VOR, the eyes move in the (Same direction, opposite direction) to the rotation of the head?

Back 57

Opposite

Front 58

What part of the cerebellum participates in eye movement control via bidirectional connections with the vestibular nuclei?

Back 58

vestibulocerebellum

Front 59

What are some of the functions of the vestibulocerebellum?

Back 59

suppresses VORs to allow tracking of an object by moving the head; smooth pursuit movements (directs eyes to follow objects moving in the visual field)

Front 60

This is located in the pontine reticular formation near each abducens nucleus?

Back 60

horizontal gaze center

Front 61

What three things give input to the horizontal gaze center?

Back 61

vestibular nuclei (head position); superior colliculus (objects in contralateral visual hemifield); cerebral cortex (for initiating voluntary and reflexive saccades)

Front 62

Axons from the horizontal gaze center project to where?

Back 62

ipsilateral abducens nucleus

Front 63

What is the function of the horizontal gaze center?

Back 63

mediates conjugate horizontal eye movements to the ipsilateral side

Front 64

lesions of the horizontal gaze center will produce hypometric or completely absent horizontal saccades to which side?

Back 64

to the side of the lesion

Front 65

This gaze center is located in the reticular formation of the rostral mesencephalon/pretectum, close to each OMC?

Back 65

Vertical gaze center

Front 66

What is the funciton of the vertical gaze center?

Back 66

mediates conjugate vertical eye movements (saccades)

Front 67

Does the superior colliculus have direct connections to the nuclei of the extraocular muscles?

Back 67

No

Front 68

How does the superior colliculus mediate eye movement?

Back 68

through projections to the contralateral horizontal/vertical gaze centers

Front 69

This structure functions in orienting eyes and head toward visual or other sensory stimuli in the contralateral visual hemifield?

Back 69

superior colliculus

Front 70

A lesion in the superior colliculus will result in what?

Back 70

disrupted ability to orient to visual stimuli in the contralateral half of the visual field; saccades are hypometric and have a high latency