Eye Movements 1 & 2

Question 1

The eye moves in small jumps called ______ to refresh the visual image several times per second so that it is never stabilized.

Answer 1

“microsaccades”

Question 2

Once an object of interest is on or near the fovea, we use slower movements, ______, to track a moving object

Answer 2

pursuit

Question 3

a rhythmic pattern of saccades and tracking movements is called _________

Answer 3

“optokinetic nystagmus”

Question 4

describe vestibular nystagmus

Answer 4

a sawtooth movement of the eyes, slow ramp opposite to head rotation, fast saccade to center of eye position,

Question 5

the direction of nystagmus is defined by the direction of the _______

Answer 5

rapid saccade

Question 6

Our eyes make ______ movements (with both eyes moving in the same direction)

Answer 6

conjugate

Question 7

we can make ________ movements (eyes moving in opposite directions, e.g., when both eyes turn nasally)

Answer 7

vergence

Question 8

describe the actions that occur during a near (accommodation) reflex.

Answer 8

Both medial recti contract, pulling the eyes nasally. The pupils constrict to increase the depth of field. The ciliary muscles contract, allowing the lens to become fatter and thus focus on a near object

Question 9

damage to the medial longitudinal fasciculus (MLF) can disconnect the coordination of medial and lateral recti during horizontal gaze movements. This condition is called ________.

Answer 9

internuclear ophthalmoplegia (INO)

Question 10

The oculomotor (III) nuclei contain motoneurons for the
\_\_\_\_\_\_\_\_\_.

Answer 10

medial rectus, inferior and superior recti and inferior oblique muscles.

Question 11

The trochlear (IV) nucleus contains motoneurons innervating the _______ muscle

Answer 11

superior oblique

Question 12

The abducens (VI) nucleus provides motoneurons for the _______ muscle

Answer 12

lateral rectus

Question 13

the lateral and medial recti are responsible for _____ .

Answer 13

horizontal rotation

Question 14

the superior rectus and inferior rectus are largely responsible for __________(with slight rotation about the visual axis as well).

Answer 14

vertical displacements

Question 15

what is caloric nystagmus.

Answer 15

a nystagmic pattern of eye movements that is independent of visual input, and elicited by a highly unusual pattern of vestibular input

Question 16

describe optokinetic nystagmus” (OKN or OPK)

Answer 16

similar in appearance to vestibular nystagmus.

A simple visual stimulus like a rotating striped drum elicits the response well (more commonly experienced as one watches the passing scene, such as telephone poles, from a moving vehicle).

Question 17

The frontal eye field can activate saccades by two pathways, one direct to the ________ and one via the ________- to the reticular formation

Answer 17

reticular formation,

superior colliculus

Question 18

If both the frontal eye field and the superior colliculus are damaged, there is _________ of the ability to make saccades.

Answer 18

permanent loss

Question 19

Saccades can be reflexively directed from the ________ or voluntarily generated by the ______. These activate the Brainstem Gaze Center (BGC) directly or indirectly through the superior colliculus (SC)

Answer 19

parietal eye field (PEF),

frontal Eye Field (FEF)

Question 20

If the _______ is damaged, saccades are less accurate and occur less often but still happen.

Answer 20

superior colliculus

Question 21

If the _________ is damaged, there is a temporary loss of the ability to generate saccades.

Answer 21

frontal eye field

Question 22

during a VOR, Rightward head rotation is signaled by horizontal canals, leftward eye rotation is produced by excitation of motor neurons to the left ______ in left abducens nucleus, and excitation of right _____ by motor neurons in right oculomotor nucleus.

Answer 22

lateral rectus,

medial rectus

Question 23

Cells in the vestibular nuclei project by way of the _________ to excite left lateral rectus motor neurons in the abducens nucleus

Answer 23

medial longitudinal fasciculus (MLF)