Neuro Opto summer 3rd quiz

Adjust fixation: when visual target moves, during head movements, when acquiring a new target

Eye Movements

Side by side movement

Medial and Lateral recti movement

Upward or downward movement

Superior and Inferior recti movement

Rotates the eye ball

Superior and Inferior Oblique

Part of the Brain responsible for Voluntary fixation

Premotor cortical region of frontal lobe

Part of the Brain responsible for Involuntary fixation

Secondary visual area in occipital cortex

Is a quick, ballistic movement that allows us to change fixation point from one target to another.

Saccadic movement

Visually guided eye movements, after catch-up saccade, eyes can track the target smoothly.

Pursuit movement

The circular group of smooth muscles in the iris

sphincter pupillae

The radial group of smooth muscles in the iris

dilator pupillae.

System responsible for controlling eye movements through coordinated actions of extraocular muscles and their neural pathways.

Ocular Motor system

Centers and pathways above the ocular motor nuclei that control and coordinate eye movements.

Supranuclear control of ocular motility

The eyes move in opposite direction

Disconjugate eye movements

The eyes move in the same direction

Conjugate eye movements

Neural system responsible for generating rapid eye movements that shift fixation from one target to another.

Saccadic System

Slow, continuous eye movements that allow the eyes to follow a moving object and maintain fixation on it.

Smooth pursuit eye movements

Has two components: saccade component and smooth pursuit component.

Optokinetic nystagmus

Eye movement reflex consisting of alternating smooth pursuit and saccadic movements in response to a moving visual scene.

Optokinetic nystagmus Reflex

Visually guided eye movement that keeps a moving object on the fovea.

Smooth pursuit

A fast eye movement that quickly shifts gaze between targets.

Saccade

Disconjugate eye movement in which both eyes move toward the nose to focus on a near object.

Convergence

Disconjugate eye movement in which both eyes move away from the nose to focus on a distant object.

Divergence

Meaning of PPRF

Paramedian Pontine Reticular Formation

The horizontal gaze center responsible for coordinating horizontal eye movements.

Paramedian Pontine Reticular Formation

When we look at the right

Right PPRF sends excitatory signals to the right abducens nucleus so the right lateral rectus muscle is activated.

Crosses the midline, sends excitatory impulse to the contralateral (in this case left) oculomotor nucleus: activation of the left medial rectus muscle.

Internuclear neuron

Coordinated upward and downward movements of both eyes controlled by supranuclear centers in the midbrain.

Vertical gaze

Supranuclear control of eye movements by cortical and brainstem centers that direct ocular motor nuclei.

Upper motor neuronal control of eye movements

Involves structures such as the frontal eye field and superior colliculus that initiate and coordinate voluntary eye movements.

Upper motor neuronal control of eye movements

Is connected with ipsilateral superior colliculus and with contralateral gaze centers of the reticular formation (horizontal and vertical gaze centers).

Frontal eye field

Lesion here causes deficit in saccadic eye movements.

Frontal eye field or in the superior colliculus

are concerned with intentional saccades to the opposite (contralateral) direction.

Frontal eye fields

If the patient has a stroke involving the anterior parts of the premotor cortex

the patient can not intentionally look at the opposite side: if the left frontal eye field is damaged, patient can not look to the right side if asked.