Week 4: Eye Movements

Question 1

Saccades

Answer 1

RAPIDLY SHIFT fovea to a visual target in the periphery

Question 2

Smooth Pursuit

Answer 2

Keeps the image of a MOVING TARGET on the fovea

Question 3

Vergence

Answer 3

Movement of the eyes toward or away from midline to ADJUST FOR DISTANCE

Question 4

Vestibuloocular Movement

Answer 4

Holds images still on retina during QUICK HEAD MOVEMENTS

Question 5

Optokinetic Movement

Answer 5

Maintains FIXATION ON NEW OBJECT during steady head movement or moving visual stimuli, a combination of smooth pursuit and saccade

Question 6

Visual Fixation

Answer 6

Holds the eye still during intent gaze; SUPPRESSION of eye movement

Question 7

Viscous Force

Answer 7

Opposes rapid eye movement

Question 8

Elastic Force

Answer 8

Restores eye to central position

Question 9

Saccadic Pulse

Answer 9

High frequency neural burst that overcomes orbital viscosity and achieves movement

Question 10

Saccadic Step

Answer 10

Steady frequency neural activity to overcome tissue elasticity and maintain steady position

Question 11

Medial Longitudinal Fasciculus Connects Which Cranial Nerve Nuclei?

Answer 11

Oculomotor, Trochlear, Abducens

Question 12

Medial Longitudinal Fasciculus Function

Answer 12

Facilitates eye movements through things like contralateral abduction and adduction, conveys information about head movement from CN VIII

Question 13

Medial Longitudinal Fasciculus Location

Answer 13

Ascends to interstitial nucleus of Cajal

Question 14

Paramedian Pontine Reticular Formation OR Paraabducens Nucleus Function

Answer 14

Processes cortical control signals and GENERATES A PULSE COMMAND which projects to the abducens nucleus

Question 15

Abducens Nucleus Components

Answer 15

Lateral rectus motor neurons AND internuclear neurons that project to the contralateral oculomotor nucleus via the medial longitudinal fasciculus

Question 16

Which nuclei control the superior rectus and superior oblique muscles?

Answer 16

CONTRALATERAL oculomotor and contralateral trochlear, respectively

Question 17

Muscles Tested From ABDUCTED Position

Answer 17

Superior and Inferior Recti

Question 18

Muscles Tested From ADDUCTED Position

Answer 18

Superior and Inferior Obliques

Question 19

Nuclei Activated for Horizontal Saccades

Answer 19

Paramedian Pontine Reticular Formation and Abducens Nucleus

Question 20

Omnipause Neurons Location

Answer 20

Nucleus of Dorsal Raphe

Question 21

Omnipause Neurons Function

Answer 21

Prevents unwanted saccades, MUST BE INHIBITED to generate a saccade

Question 22

Burst Neurons Location

Answer 22

Paramedian Pontine Reticular Formation

Question 23

Burst Neurons Function

Answer 23

Excitation of inhibitory neurons that project to the contralateral PPRF and abducens nuclei

Question 24

Integration of the PULSE velocity signal and the STEP tonic position signal is done where?

Answer 24

Medial Vestibular Nucleus and Nucleus Prepositus Hypoglossi in conjugation with the flocculus of cerebellum

Question 25

Vertical saccades require communication between BOTH of these.

Answer 25

Midbrain reticular formations of both sides through the posterior commissure

Question 26

Superior Colliculus Function

Answer 26

Works to initiate eye movements toward auditory, somatosensory, and visual stimuli

Question 27

These structures STRONGLY INHIBIT the superior colliculus

Answer 27

substantia nigra and pars reticulata