visual system

vision allows for human beings to perceive the world through various levels of light (physical property) detected as—- (electrochemical property)

photons

The levels of detection of photons are then transduced as electrical signals and interpreted by the —- of the brain for the sense of vision

occipital lobe

communicates with Middle cranial fossa posteriorly, Face anteriorly

orbit

orbit is lateral to what

nasal cavity, ethmoidal air cells

orbit is superior to what

maxillary sinus

orbit is medial to

temporal fossa

how many different bones contribute to the orbit

7

eyelids =

palpebrae

pink booger guy in the medial corner of the eye

lacrimal caruncle

are modified sebaceous glands lubricate the eye

tarsal glands

lines the inside of the eyelid and the bulbar part of the eye (not the cornea)

conjunctiva

superficial eye includes:

tarsal glands, conjunctiva palpebral, bulbar eye

tarsal glands are superior to

conjunctiva palpebral

Tears are secreted from the —— and pass over the anterior aspect of the eye moistening the conjunctiva and cornea to prevent drying out

lacrimal gland

skin part covering the lacrimal caruncle

lacrimal canaliculus

what is in constant circulation that drains out of the lacrimal puncta

lacrimal fluid

are tiny openings located on the medial (inner) edge of your upper and lower eyelids, near the corner of your eye closest to your nose, lacrimal fluid exits from here

lacrimal puncta

after the lacrimal fluid drains into the lacrimal puncta it then drains into the —— into the lacrimal sac

lacrimal canaliculus

From the lacrimal sac, lacrimal fluid drains through the —— into the inferior meatus of the nasal cavity

nasolacrimal duct

borders the orbit and is an extension of periosteal dura mater, contents of the orbit

periorbita

cushions the eye and its structures, contents of the orbit

periorbital fat

what nerves are included in the contents of the orbit

II, III, IV, branches of V1, VI

what is cranial nerve II encased in

meningeal layer of the dura mater

muscle will elevate the eyelid and is supplied by CN III

levator palpebrae superioris

superior rectus muscle is innervated by

CN III

medial rectus muscle is innervated by

CN III

inferior rectus muscle innervated by

CN III

lateral rectus muscle is innervated by

CN VI

superior oblique muscle is innervated by

CN IV

inferior oblique muscle is innervated by

CN III

structures associated with the orbit

optic canal, superior and inferior orbital fissures

what enters into the orbit via the optic canal

CN II, ophthalmic artery

what enters into the orbit via the superior orbital fissure

CN III, IV, CN V1, VI, superior ophthalmic vein

what enters into the orbit via the inferior orbital fissure

maxillary nerve (V2), inferior ophthalmic vein

By moving eye to —- position, specific eye muscles can be isolated and tested

abduction, adduction

superior rectus muscle actions

elevation, adduction, rotational intorsion

superior rectus muscle is deep to the

levator palpebrae superioris

inferior oblique muscle actions

elevation, abduction, rotational extorsion

inferior rectus muscle actions

depression, adduction, rotational extorsion

superior oblique muscle actions

depression, abduction, rotational intorsion

medial rectus muscle actions

adduction

lateral rectus muscle actions

abduction

muscles that elevate the eye

superior rectus, inferior oblique

muscles that depress the eye

inferior rectus, superior oblique

muscles that adduct the eye

superior, medial, inferior rectus

muscles that abduct the eye

inferior, superior oblique, lateral rectus

muscles that do rotational intorsion

superior oblique, rectus

muscles that do rotational extorsion

inferior oblique, rectus

The overall function of the eye is to focus light on the

retina

Once light hits the retina, signal tranducton from the photons of light stimulate

action potentials

are able to convert light (a physical property) to an electrochemical signal along with other sublayers in the neural retina

retinal ganglion cells

pathway order of sight

object, cornea, lens, retina

light rays are bent by

cornea and lens

The anterior and posterior chambers contain

aqueous humor

the vitreous body contains

vitreous humor

is the clear, gel-like substance that fills the space between the lens and the retina in the posterior segment of the eye

vitreous humor

is a clear, watery fluid found in the anterior segment of the eye, specifically in the anterior and posterior chambers

aqueous humor

three major layers of the eye from superficial to deep

corneosclearal coat, uvea, retina

Cornea, Sclera - most superficial layer of the eye

corneosclearal coat

Iris, Ciliary Body, Choroid, Lens* - middle layer of the eye, basically the vascular layer of the eye

uvea

Fovea centralis with Macula lutea, Optic disc - deepest layer of the eye

retina

5/6^th of the covering of the eye (white), gives the eye firm structure to it’s shape and insertion points for the extraocular muscles, part of the corneosclearal coat

sclera

helps to bend light as it enters the eye, part of the corneosclearal coat

cornea

a collection of capillaries between the corneaoscleral coat and the retina, deep to the sclera, makes up the uvea

choroid

deep to the iris, (both make up parts of the uvea)

ciliary body

what part of the retina makes up the majority of it

neural

where is the non neural part of the retina

anterior

focuses the light on the retina

lens

arrangement of the —— (middle layer of cornea, made of collagen fibers) facilitates light bending and is transparent to allow for light to pass through

corneal stroma

The place on the eye where the cornea meets the sclera

corneosclearal limbus

Pigmented epithelium differences, Cell types different from anterior to posterior, Constrictor and dilator pupillae muscles

iris

is found at the rim of the iris and is circular, When it contracts, it will caused the iris to stretch towards the pupil

constrictor pupillae muscle

is found on the peripheral parts of the iris in longitudinal sheets of smooth muscle. When it contracts, it pulls the rim to move away from the pupil

dilator pupillae muscle

Blue eyes =

no pigment

Three principal component of the lens:

lens capsule, subcapsular epithelium, lens fibers

extend from the ciliary epithelium to the equatorial region of the lens capsule and holds the lens in place

zonular fibers

is a transparent basement membrane like structure enclosing the lens substance

lens capsule

the lens becomes opaque, light cannot be focused on the retina, result from inadequate nutrients to the lens, making vision obscure and unclear

cataracts

parts of the ciliary body

ciliary muscle and processes

Under parasympathetic control for accommodation, part of the ciliary body

ciliary muscle

Non-pigmented epithelium secrete aqueous humor, finger like protrusions from ciliary body

ciliary processes

When ciliary body muscle contacts, the lens

widens/fattens up

the ciliary muscle contracts, the ciliary body with inserted zonula fibers moves closer to the lens, the tension is reduced and the lens rounds up - what kind of vision

close vision

When ciliary body muscle relaxess, the lens

narrows/flattens up

the ciliary muscle is relaxed, the ciliary body with zonular fiber inserts moves away from the lens, the tension of the zonular fibers increases and the lens flattens - what kind of vision

distant vision

Aqueous humor accumulates in the —— of the eye. From here, it drain back into the venous system

anterior chamber

Aqueous humor is synthesized by the —-, circulates from the ——-, then drains into the ——

ciliary processes, posterior to anterior chambers, scleral venous sinus

Blockage of the Canal of Schlemm (scleral venous sinus) leads to increased intraocular pressure, a leading cause of optic nerve damage and vision problems

glaucoma

aqueous humor drains from the scleral venous sinus into the episcleral veins into the

superior and inferior ophthalmic veins

Vascularized layer, Choriocapillaries supply the retina

choroid

Macular degeneration or retinal detachment can occur when there is separation between the

choroid and neural retina

accumulation of pigment (black spots), Obliteration of capillaries*, Ruptured blood vessels*

drusen

retina cell layers from superficial to deep

retinal pigment epithelium, rod and cones, bipolar cell layer, ganglion cell layer

This layer absorbs light that is not detected by the photoreceptors. It also forms part of the blood-retinal barrier, will also help degrade disc pigments as those structures are released from the rods and cones

retinal pigment epithelium

are where photons of light are detected

rod and cones cell layer

Minority photoreceptor type, Lower sensitivity, are responsible for photopic or daytime vision, providing color information and sharpness of images, contain 1 of 3 photopigments, highest density towards fovea

cones

cone types

red, green, blue

Predominant photoreceptor type, High sensitivity, 1 type: grays, decrease density towards fovea, are responsible for scotopic vision or nighttime vision, extremely sensitive to white light 

rods

a gradient of amount of bond visual pigment complex by photons (Light)

intensity

is that there is a high degree of integration with rods and cones as well as retinal ganglion cells. This is one of the reasons why visual information has a high level of integration from the eye as well as within the central nervous system

bipolar cells