Six extraocular muscles move
Each eye.
Medial rectus muscle,
Lateral rectus muscle,
Superior rectus muscle,
Inferior rectus muscle,
Superior oblique muscle
Inferior oblique muscle
Five types of eye movements
Gaze-stabilization mechanisms: found in all animals with visual systems.
Gaze-shifting mechanisms: observed in animals that have retinal specializations, such as the primate fovea, which can be used to examine a limited region of visual space at higher acuity.
Gaze-stabilization mechanisms
Vestibulo-ocular systems: move the eyes in responses to the position information deriving from the vestibular system, the semi-circular canals.
Optokinetic systems: computing the speed and direction at which the visual world is shifting by the photoreceptors across the retina.
Vestibulo-ocular reflex (VOR)
A subject is placed in a stationary drum with colored striped on the interior surface and on a rotating stool.
Nystagmus
VOR is plastic
neuro3e-fig-18-12-0.jpg
Gazing-shifting mechanisms
Saccadic systems: rapidly shifts gaze from one point to another.
Smooth pursuit system: allows the fovea to tack a moving target as it slides across a stationary background.
Vergence movements: for animals with both the fovea-like specialization and binocular vision, scrutinizing a single visual target with both eyes and have evolved a special eye movement system to control the angle formed by the line of gaze of the two eyes.
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