Kenyon-Eye movements

Question 1

Dysfunction with eye postion is typically caused how?

Answer 1

via lesions in brainstem or cranial nerves

Question 2

Adults with leasions in the extraocular muscles or their nerves have (blank)

Answer 2

diplopia (double vision)

Question 3

Infants and children with lesions in the extraocular muscles or their nerves have (blank) that can result in loss of function in the affected eye.

Answer 3

strabismus

Question 4

Where do you find lower motor neurons?

Answer 4

cell bodies in the brainstem or spinal cord

Question 5

Where do lower motor neuron axons end?

Answer 5

in neuromuscular junctions with skeletal fibers

Question 6

Are lower motor neurons excitatory or inhibitory and via what neurotransmitter and receptor?

Answer 6

excitatory via Ach and Nictonic muscle receptors

Question 7

What are upper motor neurosn and where do their axons end and are they excitatory or inhibitory?

Answer 7

cell bodies in the brainstem or cerebral cortex, axon end in synapses on other upper motor neurons, local circuit neurons, lower motor neurosn or some combo
The are both excitatory and inhibitory

Question 8

What are the three nuclei of the brainstem that controls external muscles of the eye?

Answer 8

oculomotor III
trochlear IV
abducens VI

Question 9

Injruy to the brainstem (trauma, ischemia, etc) will cause defects in (blank) positioning that reveal the location of the injury

Answer 9

eye positioning

Question 10

Where does the superior oblique muscle attach on the eyeball?

Answer 10

back

Question 11

Contraction of the superior oblique does what to the eye?

Answer 11

causes depression and medial rotation

Question 12

How can you get torsion (rotates eyeball inward) without depression?

Answer 12

superior rectus

Question 13

T or F

the effect of the superior oblique muscle varies with direction of the eye.

Answer 13

T

Question 14

With abduction of the eyeball, contraction of the superior oblique does more (blank)

Answer 14

intorsion

Question 15

With ADduction of the eyeball, contraction of the superior oblique does more (blank)

Answer 15

depression

Question 16

There are (blank) in brainstem nuclei that go to the extraocular ey muscles and are controlled by local circuit neurons and upper motor neurons located in brainstem and cortex

Answer 16

lower (alpha) motor neurons

Question 17

Do you find at the end of motor end plates?

Answer 17

acetylcholine, nicotinic ACh receptors

Question 18

In the extraocular eye muscles, 1 motor neuron activates (blank) muscle fibers

Answer 18

3

Question 19

THe oculomotor nerve has what kind of fibers?

Answer 19

somatic and autonomic

Question 20

this nerve contains axons of motor neurons to the external muscles of the ipsilateral eye that are not served by 4 or 6 and axons of motor neurons to somatic muscle of eyelid and autonomic axons to pupil (ipsilateral)

Answer 20

Oculomotor (III)

Question 21

The trochlear nerve contains axons that are ipsilateral or contralateral to superior oblique?
Does it contain somatic or autonomic fibers?

Answer 21

contralateral

somatic

Question 22

The abducens nerve gives motor neurons to ipsilateral or contralateral lateral rectus?

Answer 22

ipsilateral

Question 23

The trochlear nerve exits the dorsal surface of the midbrain and (blanks).

Answer 23

crosses over

Question 24

Can you get a legion that messes up both trochlear nuclei? Does it have to be big to do so? Does this happen often?

Answer 24

yes
nope
nope

Question 25

what happens if you get a legion on your trochlear nerve?

Answer 25

paralysis of superior oblique muscles (lower motor neuron syndrome) diplopia on looking downwards (super hard to get up stairs)

Question 26

How do you compensate for you messed up superior oblique muscle that is making you get diplopia when looking down?

Answer 26

you tilt your head toward the weak muscle (i.e if you have a legion in the left eye, you will put your right ear to your right shoulder to compensate)

Question 27

How does the abducense nerve travel from the abducens nuclei in the pons.

Answer 27

abducens nerve comes out of abducens nuclei to the ipsilateral lateral rectus muscle (DOES NOT CROSS OVER)

Question 28

What is the most common palsy? why?

Answer 28

CN 6 palsy, because the course of the nerve is sooooo long

Question 29

What happens if you lose your CN 6

Answer 29

you get paralysis of LR and you get failure of abduction on affected eye and can intort causing double vision

Question 30

How do people with CN 6 compensate for the lack of abduction and increased intorsion?

Answer 30

rotation of head

Question 31

Why do you get intorsion when you lose your abducens nerve?

Answer 31

because of the unopposed action trochlear nerve (superior oblique causes intorsion)

Question 32

How does the oculomotor nerve travel from the midbrain?

Answer 32

from the oculomotor nucleus | to ipsilateral superior, inferior and medial rectus and to inferior oblique (NO CROSSOVER)

Question 33

Where is the oculomotor nucleus located?

Answer 33

under superior colliculus

Question 34

Neurons in the (blank) nucleus also innervate the levator muscles of the eyelid

Answer 34

oculomotor nucleus

Question 35

What extraocular nerve carries axons from edinger-westphal nucleus? What does this mean?

Answer 35

oculomotor nerve | oculomotor nerve allows for pupillary contriction via sympathetics that travel on it via the edinger westphal nucleus

Question 36

What does your eye look like if you lose your oculomotor nerve?

Answer 36

Down and out (cuz of unopposed action of superior oblique and lateral rectus muscle) Drooping of eyelid dilated pupils paralysis of accomodation

Question 37

What is the near reflex triad test and what does it do?

Answer 37

it tests oculomotor nerve functionby looking at vergence adductioon of eyeballs, accomodation of the lens, pupillary restriction

Question 38

What are the four types of eye movements?

Answer 38

saccades smooth pursuit vergence vestibulo-ocular eye movements

Question 39

What are saccades?

Answer 39

rapid ballistic movements that put an image on the fovea

Question 40

What are smooth pursuit movements?

Answer 40

slow tracking movements that keep a moving image on the fovea (voluntary) I.e keep a moving target on the fovea

Question 41

What are vergence movements?

Answer 41

aligning the fovea with targets at different distances (tracking something moving toward or away from you) AND moves the eye in opposite directions (conjugate movements) so that the image is positioned in both foveas

Question 42

What do vestibulo-ocular movements do?

Answer 42

compensate for movements of the head driven by the vestibular system. I.e vestibulo-ocular movements hold images stable during brief head movements

Question 43

The semicircular canals detect (blank) of the head.This info is used to direct the eyeballs to move in the (blank) direction (i.e to maintain the field of view)

Answer 43

rotation | opposite

Question 44

When do the vestibuloocular movements work best?

Answer 44

during acceleration or rapid rotation (i.e movements that are too fast and abrupt for tracking)

Question 45

The (blank) the movements the more important vestibulo-ocular system becomes

Answer 45

quicker

Question 46

During constant or slow rotation, vestibulo-ocular compensatory eye movements cease after (blank) seconds.

Answer 46

30 (visual cues will then be important)

Question 47

the quicker the movement, the more important the (blank) system

Answer 47

vestibulo-ocular

Question 48

T/F: Each semicircular canal transmits a tonic signal to the vestibular nerve even when the eyes are still

Answer 48

T

Question 49

t/F: An imbalance in the signals from the vestibular system will result in nystagmus when the head is still.

Answer 49

T

Question 50

T/F: Saccades are both voluntary and reflexive.

Answer 50

T; reflexive: seeing something coming at you from your periphery; voluntary: looking at individual parts of an image

Question 51

T/F: the eye movements in REM sleep are saccades

Answer 51

True

Question 52

the amplitude of the saccade correlates with the (length/amplitude) of the burst of action potentials going to eye muscles

Answer 52

length of duration of burst of AP's

Question 53

As the eye moves more laterally, the baseline firing of the lateral rectus (inc/dec/stays the same)

Answer 53

increases

Question 54

In what three nuclei are the lower motor neurons of the eye located?

Answer 54

1. Oculomotor 2. Trochlear 3. Abducens

Question 55

The PPRF/reticular center is the (horizontal/vertical? gaze center

Answer 55

horizontal

Question 56

Both of the gaze centers are in the (blank) formation

Answer 56

reticular formation

Question 57

The horizontal and vertical gaze centers contain the (blank) motor neurons which talk to the oculomotor, trochlear, and abducens

Answer 57

upper motor neurons

Question 58

T/F: the lateral rectus is directly innervated by lower motor neurons in the abducens nucleus

Answer 58

T

Question 59

T/F: there are interneurons present in the abducens nucleus

Answer 59

T

Question 60

Where do the internuerons of the R abducens nucleus head? What tract do they travel on?

Answer 60

They go to the L oculomotor nucleus via the medial longitudinal fasciculus

Question 61

T/F: the portion of the medial longitudinal fasciculus between abducens and oculomotor is a local circuit neurons

Answer 61

T

Question 62

Nuerons in the PPRF drive inhibitory interneurons (local circuit) that synapse in the (ipsi/contra) abducens

Answer 62

contralateral abducens

Question 63

Upper motor neurons found in which two structures are used in saccade targeting?

Answer 63

Superior colliculus (midbrain and frontal eye field (frontal lobe)

Question 64

Light on a particular spot on the retina can be mapped to a particular spot on the (sup colliculus/frontal eye field)

Answer 64

superior colliculus

Question 65

Motor neurons in the sup colliculus will drive the eye to move the image to the (blank)

Answer 65

fovea

Question 66

Are saccades used to move eyes to a specific target or used to move eyes in a specific motion or amount?

Answer 66

To a specific target

Question 67

T/F: the parietal lobe is used in commanding saccades

Answer 67

True! Besides sup colliculus and FEF, the occipital lobe (vision) and parts of parietal control visual upper motor neurons

Question 68

Besides the retinal mapping on the sup colliculus, what two other senses are also mapped there?

Answer 68

Auditory and somatic stimuli, so you can look quickly at something you see or hear!

Question 69

Does the FEF have multiple paths to the PPRF?

Answer 69

Yes

Question 70

What tract does the FEF take to the sup colliculus?

Answer 70

corticobulbar

Question 71

T/F: partial damage in a center between the FEF and the PPRF can be compensated

Answer 71

T

Question 72

Smooth pursuit movements are driven through which gaze center?

Answer 72

horizontal

Question 73

T/F: the parietal and occipital lobes are necessary for smooth pursuit

Answer 73

true

Question 74

T/F: the occipital and parietal lobes generate the slow phase of optokinetic nystagmus

Answer 74

T

Question 75

Discuss the construction of a stable image. We're always moving our eyes, so how do we look at anything and get a clear picture?

Answer 75

The visual centers know what commands were sent to the eyes and uses this information to construct a stable image from multiple "snaphsots"