Visual Systems Flashcards
What are the 3 layers (tunics) called?
- fibrous tunic
- vascular tunic
- sensory tunic
What does the fibrous tunic consist of? (2)
- cornea
- sclera
What does the vascular tunic consist of? (3)
- iris
- ciliary body
- choroid
What does the sensory tunic consist of? (1)
- retina (pigmented layer and neural layer)
What is a transparent structure that allows light to enter the eye while slightly refracting it?
cornea
What is made of collagen and is an extension of the dura mater of the brain?
sclera
What is referred to as the typical “white of the eye” and is observed through the overlying conjunctiva?
sclera
What contains blood vessels, as well as numerous melanocytes for light absorption?
choroid
The choroid provides nourishment for the ___________, as well as absorbing any scattered light rays
retina
What three things modify the amount and quality of light that enters the eye?
- iris
- lens
- ciliary body
The eye is divided into two regions:
- anterior chamber
- posterior chamber
The anterior chamber is filled with ______________ body.
aqueous
The posterior chamber is filled with ____________ body.
vitreous
What are the four components that comprise the anterior chamber?
- ciliary body
- cornea
- iris
- lens
What are the four components that comprise the posterior chamber?
- choroid
- retina
- optic nerve
- optic disc
The ciliary body produces _______________
aqueous humor
The ____________________ relaxes the suspensory ligaments allowing the lens to round it up.
ciliary muscle
The iris is associated with two smooth muscles:
- the circular sphincter pupillae muscle (outer edge of the iris)
- the radial dilator pupillae muscle
Retinal vessels from the __________ artery originate from the __________.
ophthalmic
optic disk
What is the name of the structure that is where the optic nerve fibers exit the retina?
optic disk
The _____________ is responsible for the high-resolution, color vision possible in good light .
macula
The __________ is the area of the macula with the highest concentration of photoreceptors, and highest sensitivity to color and fine details.
fovea
The part of the retina that lies closer to the nose than the fovea is referred to as _________________.
nasal retina
The part of the retina that lies near the temple is called _______________.
temporal retina
The retina is composed of 3 sections:
1.) 3 neural cell body layers
2.) 3 intermediate layers with neural projection (axons and dendrites)
3.) 2 external layers
What are the 2 external layers of the retina called?
- optic nerve fiber layer
- pigment cell layer
What are the 3 neural cell body layers called?
- ganglion cell layer
- inner nuclear layer
- outer nuclear layer
What are the 3 intermediate layers with neural projections called?
- inner plexiform layer
- outer plexiform layer
- layer of rods and cones
What mediate night vision?
rods
What mediates bright light and color vision?
cones
What provide visual and color acuity?
cones
What respond to low light?
rods
What helps with black and white vision?
rods
What is the name of the light receptor in the rods?
rhodopsin
What are the photopsins in the cones?
blue, red, and green
How many rods and cones are there in the eye?
120 million rods
6 million cones
All cones are concentrated in the _________.
fovea
The visual cortex processes vision from the _____________ eye and visual field.
contralateral
Fibers from the nasal retina decussate at the __________________.
Optic chiasm
Fibers from the temporal retina remain ________________________.
ipsilateral
A _________________ is one half of the visual field.
hemifield
A hemifield is usually divided vertically through the _______________ into the left or fight visual field.
fovea
The ___________________ of the contralateral side conveys the majority of visual information for a given hemifield.
nasal retina
(LEFT/RIGHT) hemifield includes the right temporal retina and left nasal retina.
LEFT
(LEFT/RIGHT) hemifield involve the left temporal retina and right nasal retina.
RIGHT
What is the visual pathway? (7 steps)
- Retina
- Optic nerve
- Optic chiasm
- Optic tract
- Lateral geniculate nucleus (LGN)
- Optic radiation
- Primary visual cortex
Each point of the 2D visual field perceived by the ____________, maps on to a specific group of neurons in the visual cortex to create 3D image representation!.
retina
The visual cortex organizes _________________________-lly.
somatotopically
What is formed by 6 cell layers, which receive alternating projections from fibers originated in the nasal (contralateral) and temporal (ipsilateral) retina.
LGN
The LGN then projects organized retinotopic fibers to the _______________.
cortex
How many visual cortices are there?
8
Which visual cortices involve primary visual cortex, receives inputs from LGN?
V1
Which visual cortices involve secondary receives afferents from V1 and the pulvinar?
V2
V2 sends efferents to V___ and V___
V3 & V4
Which visual cortices process form and motion info?
V3 and V3a
Which visual cortex involve color and form processing?
V4
Which cortices involve association processes?
V7 and V8
The ventral pathway is known as the ______ stream.
“what”
The dorsal pathway is known as the ______ stream.
“where”
Which visual processing pathway involves color, texture, pictorial detail, shape, and size?
Ventral (“what”)
What visual processing pathway involves spatial processing, location, and movement?
Dorsal (“where”)
The ventral pathway goes to which cortex?
inferotemporal cortex
The dorsal pathway goes to which cortex?
parietal cortex
What is the ventral pathway of the control of the lateral eye position?
retina –> superior colliculus –> pons (paraabducens nucleus, PPRF) –> CN VI abducens
What is the dorsal pathway of the lateral eye position?
Retina –> LGN –> Primary visual cortex –> Post parietal cortex –> Frontal eye fields –> Basal ganglia–> Superior colliculus –>Pons, CV VI
