Visual System

Cornea

Superficial layer on the anterior eye

Sclera

Superficial layer on the posterior eye

Iris

Pigmented layer of the eye that constricts and dilates the pupil in response to light

Aqueous chamber

Fluid-filled space between the iris and lens

Lens

Part of the eye that focuses on nearby objects when compact and far vision when stretched

Ciliary muscles

Muscles that stretch the lens when contracted

Vitreous chamber

Fluid-filled space between the lens and retina

Retina

Sensory receptors of the eye

Optic disc

Point where nerve fibers converge to the optic nerve

Macula

Point near the center of the eye of high photoreceptor concentration

Fovea

Point near the center of the eye of highest photoreceptor concentration

Retinal ganglion cells

Neurons that transmit visual information to the optic nerve

Horizontal cells

Cells that inhibit center field photoreceptors when surround field photoreceptors are excited

Bipolar cells

Cells that transmit signals from multiple rods and singular cones to retinal ganglion cells

Off-bipolar cells

Cells excited by glutamate signals from photoreceptors

On-bipolar cells

Cells inhibited by glutamate signals from photoreceptors

Amacrine cells

Cells that transmit signals from bipolar cells to bipolar cells and retinal ganglion cells

Photoreceptors

Graded glutamatergic cells embedded in pigmented epithelial tissue inhibited by photons

Rods

Photoreceptors responsible for low-light monochrome vision abundant outside of the fovea

Cones

Photoreceptors responsible for high-detail color vision abundant in the fovea

Outer segment

Photosensitive portion of rods and cones

Nasal visual field

The portion of the monocular visual field contralateral to the eye

Temporal visual field

The portion of the monocular visual field ipsilateral to the eye

Optic nerve

Axons traveling from the retina to the optic chiasm

Optic chiasm

Point where axons from the nasal retinal fields desecute

Optic tract

Axons traveling from the optic chiasm to the lateral geniculate nucleus

Lateral geniculate nucleus

Region of the thalamus receiving visual input

Optic radiations

Axons travelling from the lateral geniculate nucleus to the primary visual cortex

Homonymous hemianopia

Visual defect created by damage to an optic tract or lateral geniculate nucleus

Bitemporal hemianopia

Visual defect created by damage to the optic chiasm

Quadrantanopia

Visual defect created by damage to an optic radiation

Ocular dominance columns

Regions of the primary visual cortex alternating between input from the left and right eyes

Orientation columns

Regions of the primary visual cortex sensitive to visual input at specific angles

Blobs

Regions of the primary visual cortex sensitive to color stimuli

Dorsal stream

Projections from the primary visual cortex to the posterior parietal cortex recognizing movement and spatial relations of visual

Ventral stream

Projections from the primary visual cortex to the temporal cortex recognizing the content of visual input