Visual System Flashcards
Visual System
Outer layer of the eye consists of = ?
Outer layer of the eye consists of:
- Sclera: Tough connective tissue, maintains shape of eye.
- Cornea: Transparent, allow light to enter
- Conjunctiva: Thin layer, lubricates the eyes
Visual System
Middle layer of the eye consists of = ?
Middle layer (Vascular) of the eye consists of:
- Choroid: Filled with blood vessels thatbring oxygen and nutrients to the eye.
- Iris: 2 layer of pigmented smooth muscle, regulates the diameter of pupil.
- Ciliary muscles: Change the shape of the lens.
- Pupil: Hole in the center of iris that allow light to enter.
Visual System
Inner layer of the eye consists of = ?
Inner layer (Vascular) of the eye consists of:
- Retina: Photoreceptors (rods and cones) that detect light waves, conversion of light energy to electric energy.
- Cones: Color vision
- Rods: Low light levels
- Fovea: Greatest visual acuity
- Optic disk: Optic nerve and blood vessels supplying the eye pass through the retina- blind spot.
Visual System
- Visual pathway begins with cells in the retina that convert light into neural signals.
- Optic nerve is the bundle of axons that pass from the ? to the ?.
Optic Pathways
- Visual pathway begins with cells in the retina that convert light into neural signals.
- Optic nerve is the bundle of axons that pass from the retina to the optic chiasm.
- Nerves merge at the optic chiasm, where some axons cross the midline.
Visual System
- Optic tract conveys visual information from chiasm to the lateral geniculate.
- Postsynaptic neurons travel from the lateral geniculate through optic radiations to the _ ? _ cortex.
Optic Pathways
- Optic tract conveys visual information from chiasm to the lateral geniculate.
- Postsynaptic neurons travel from the lateral geniculate through optic radiations to the primary visual cortex.
- The primary visual cortex is the region of the cortex that receives direct projections of visual information.
Visual System
The cortical destination of visual information depends on which half of the retina processes the visual information:
- Nasal retina = ?
- Temporal retina = ?
- Left nasal field = ?
- Right temporal field = ?
- Left nasal hemiretina = ?
- Right temporal hemiretina = ?
Nasal retina - nearest the nose
* Information from the nasal half of each retina crosses the midline in the optic chiasm and projects to the contralateral visual cortex.
Temporal retina - nearest the temporal bone
* Information from each temporal half continues ipsilaterally through the optic chiasm to the ipsilateral cortex.
- Left nasal field and right temporal field = right visual filed
- Left nasal hemiretina and right temporal hemiretina = right optic tract
Visual System
Purpose of oculomotor system = ?
Purpose of oculomotoe system = To produce eye movements to direct the fovea toward the target of interest.
Visual System
6 extraocular muscles =
- lateral rectus = abd
- medial rectus = add
- inferior rectus = down
- superior rectus = up
- inferior oblique = extorsion (ER- upper pole of theeyeoutward), elevation, and abd.)
- superior oblique = intorsion (IR), depression, and abd.)
Visual System
Muscle & Action
pink
- Lateral Rectus
- Abduction
Visual System
Muscle & Action
pink
- Medial Rectus
- Adduction
Visual System
Muscle & Action
- Inferior Rectus
- Downward
Visual System
Muscle & Action
- Superior Rectus
- Upward
Visual System
Muscle & Action
- Inferior Oblique
- Extorsion
- (ER - upper pole of theeyeoutward), elevation, and abd.)
Visual System
Muscle & Action
- Superior Oblique
- Intorsion (IR), depression, and abd.)
Visual System
Two objectives of eye movements = ?
- Gaze stabilization (or visual fixation): Keeping the position of the eyes stable during head movements to ensure that the environment does not appear to bounce.
- Direction of gaze: Directing the gaze at visual targets
Visual System
Eye movements are either:
- ?
- ?
Eye movements are either:
- Conjugate: both eyes move in the same direction.
- Vergence: eyes move toward the midline or away from the midline (convergence vs. divergence).
Visual System
Direction of gaze toward selected objects is accomplished by = ?
Direction of gaze toward selected objects is accomplished by:
- Saccades: fast eye movements to switch gaze from one object to another;Example: reading a book; shifts the reader’s gaze from the text to another person/ object.
-
Smooth pursuits: eye movements that are used to follow a moving object. Example: watching a hot balloon in the air
Moving visual stimulus is essential for the production of smooth pursuit movements.
Visual System
Cortex = ?
Frontal Eye Fields: Control volunary eye movements.
Visual System
Cortex = ?
Occipital and Temporal Regions: Provide information for pursuit ete movements.
- Provide information about movement of visual objects, essential for optokinettic and smooth eye movements.
Visual System
Cortex = ?
Posterior Parietal Cortex: Spatial information for eye movements.
Visual System
Cortex = ?
Dorsolateral Prefrontal Cortex: Important for saccades.
