Test 2: Visual Flashcards
What CN does vision
CN II- optic nerve
Why is CNII NOT a peripheral nerve?
retinal structure from diencephalon development
myelinated neurons with oligodendycytes-CNS
What is the pathway of light traveling into the eye?
Iris through lens to retina- focused on fovea to optic nerve
What does the pupillary constrictor muscle do?
controls amount of light entering the eye via controlling the iris
- parasympathetic constricts
- synpathetic relaxes
What do ciliary muscles do?
adjusts lens thickness to help bend light to focal point (fovea)
- visual accomodation
- paraysmp: thickens
- sympathetic relaxes
What is the retina? what’s in it?
has visual receptors lining the walls of the eye
- macula on posterior wall= increase density
- fovea in macula= highest density of cones
What is the optic disk? what’s in it?
blind spot
- axons from retina and vasculature exit through here
- vascular from internal carotid-opthalamic vessels
What makes up the fovea?
5 types of neurons
- mainly photoreceptors= rods and cones
- retinal ganglia cells
Everything flipped upside down!!
What are rods?
photoreceptor in fovea
- ALL wavelengths visible light
- dense around macula
- detects light levels and motion– course vision
What are cones?
photreceptor in fovea
- 3 types of pigements to transduce color wavelenths: red, green, blue
- most dense around fovea where macula has greatest visual acquity
What are retinal ganglia?
output neurons- 1CB of visual pathway
- axons collect at optic disk and once exit eye all travel as CNII
- unmeylinated axons until exit disk-> myelinated with oligodend
What are pigment epitheliums? what are the 3 types?
melanin that absorbs light to decrease scatter
- opesins: photo pigment for color
- rodespin: light/dark
- melanopsin: special ganglia with melanin
What are the 4 possible pathways of visual perception?
- Primary pathway-> V1
- occipital pole - Suprachiasm nucleus of hypothal
- diurnal clock
- light/dark
- melanopsin - Pretectal nuclei (midbrain)
- pupil constrictor/thicken lens
- parasympathetic reflexes - Superior colliculus (midbrain)
- eye movements relative to environment
What is the 1neron characteristic of the Primary Visual pathway?
axons off of photoreceptors
- collect/sort 3 regions of projections
- all axons travel in ipsilateral optic nerve
- enter chiasm: vulnerable to pituitary tumor damage
Nasal: 60% decussate in chiasm-> contrlateral optic tract
Temporal: 40% stay ipsilateral-> ipsilateral optic tract
Tracts-> LGN -> internal capsule -> optic radiations -> VI
What is the BA number of V1
BA 17