Eye Anatomy Flashcards
Choroid
The choroid consists primarily of blood vessels that nourish the retina so that it can continue to function.
It is sandwiched between the sclera and the retina.
Melanin in the choroid absorbs excess light, which prevents reflection and scattering of light within the eyeball.
Cornea
The clear, transparent tissue that is located on the very front (anterior) portion of the eye. The cornea provides the major refractive (focusing) power of the eye. It has a curvature somewhat greater than the rest of the globe.
The cornea has five layers. They are, from front to back: epithelium, Bowman’s layer, stroma, Descemet’s membrane, and endothelium. The cornea is avascular (having no blood vessels)
Iris
Colored part of the eye. The iris consists of two circular muscles with a hole in the middle, called the pupil. The iris sphincter and dilator muscles control the size of the pupil for maximum visual performance.
Crystalline Lens
Provides focusing power to the eye. It allows adjustment of the eye to focus from distance objects to near objects. It is the second most powerful refractive medium.
The resilient, transparent structure in the eye that focuses light by changing curvature of its front surface. It is located near the front of the eye, directly behind the pupil.
Optic Nerve
Nerve that carries impulses from the retina to the brain. It transmits the signals from the rods and cones in retina to the brain.
This is the pathway between the eye and the brain along which the signals produced by the retina travel to the brain.
Pupil
Round hole in the center of the Iris through which light passes. The pupil ordinarily appears black because there is very little light coming from the dark chamber behind it.
Sinuses
Air spaces within the bones. Poor drainage, infection, or cancerous enlargement of the sinuses may cause headaches, pain around the eye (periorbital), or pain described as coming directly from the eye.
Suspensory Ligaments
Long, thin fibers which connect the crystalline lens to the ring of ciliary muscles
What Are The Layers of Cornea Front to Back?
1.) Epithelium
2.) Bowman’s layer
3.) Stroma
4.) Descemet’s membrane
5.) Endothelium
How Many Muscles Control The Eyes (Extraocular Muscles)?
Six
Limbus
Where the the sclera and cornea meet.
Palpebral Conjuctiva
Clear/ cellophane-like tissue that lines the inside surface of the eyelids
Blind Spot
Small portion of the visual field of each eye that corresponds to the position of the optic disc (also known as the optic nerve head) within the retina. There are no photoreceptors (i.e., rods or cones) in the optic disc, and, therefore, there is no image detection in this area.
Pupil
Round opening in the center of the iris that changes size to let light into the eye. It gets smaller in bright light and larger as the amount of light decreases.
Zonular Fibres
Ring of fibrous strands forming a zonule (little band) that connects the ciliary body with the crystalline lens of the eye. They hold the crystalline lens firmly in place. Collectively known as suspensory ligament of the lens. The zonules also work with the ciliary muscles to help the lens accommodate (change focus).
Eyelid
Description: fold of skin which covers the eye
Purpose: cleaning and protecting the eye
Ocular Adnexa
Adjacent structures of the eye:
Eyelids
Eyelashes
Eyebrows
Orbit
Lacrimal apparatus
Tarsal Plates
Extra Ocular Muscles
Conjunctiva
Sinuses
Air spaces within the bones.
Headaches, pain around the eye (periorbital), pain coming from eye
Lacrimal Gland
Supplies most of the tears to eye.
It is above (superior) & temporal to eye, behind orbital rim
Nasolacrimal Duct
Drainage system for tears to leave eye.
Connected to nasal passage
Sclera
White part of eye.
Tough, fibrous tissue that gives shape/structure to eyeball
Pupil
Round hole in center of Iris through which light passes.
Normally black due to little light from chamber behind it.
Iris
Colored part of eye.
Consists of 2 circular muscles with a hole in the middle (Pupil):
Iris Sphincter
Dilator Muscles
These control the size of the Pupil for maximum visual performance.
Uvea
Pigmented middle layer of eyeball.
Has 3 segments:
Iris
Ciliary Body
Choroid
Anterior Chamber
Area inside the eye, behind cornea, and in front of Iris.
This area is filled with clear, watery fluid called Aqueous Humor.
Cornea
Clear, transparent tissue that is located on the very front (anterior) portion of the eye.
Most powerful refractive media of the eye.
Provides most of the eye’s ability to focus light.
Has a curvature somewhat greater than the rest of the globe, so slight furrow marks its junction with the sclera.
The junction of the Sclera and the cornea is called the limbus.
The cornea is avascular (no blood vessels).
Cornea has 5 layers.
Aqueous Humor
Clear, watery fluid produced by the ciliary body.
It fills the front part of the posterior chamber & the entire anterior chamber.
It provides nutrients for the lens & posterior cornea & carries away waste products.
Also responsible for maintaining the IOP because it’s the only fluid continually produced in the eye.
Ciliary Body
Circular structure in the eye that’s connected to the Iris & is located directly behind it.
It produces the aqueous fluid inside the eye.
Posterior Chamber
The area located inside the eye, behind the Iris, & in front of the lens.
Suspension Ligaments
Long, thin fibers which connect crystalline lens to the ring of ciliary muscles.
Macula
Central part of the retina that provides clear central vision, used for seeing detail.
It is an area from 3 - 5 mm in diameter, with the foveal depression (fovea centralis) at its center.
Fovea Centralis
Area in the macula (approx 1.5 mm diameter) where visual acuity is the sharpest.
Fovea contains highest number of cones, which are responsible for daytime vision & color vision.
Retina
Innermost layer of the eye, which contains rods & cones.
It lines the sclera.
Is where light coming into the eye is focused.
Images that fall on the nerve cells of the retina are then transmitted to the brain via the optic nerve, where they are interpreted.
Optic Nerve
The nerve that carries impulses from the retina to the brain.
It transmits the signals from the rods & cones to the brain.
Optic Disc
Circular area in the back of the inside of the eye where the optic nerve connects to the retina.
Also called the optic nerve head, the optic disc is the portion of the optic nerve that is formed where all the retinal nerve fibers meet.
Because there are no rods & cones overlying the optic disc, its insensitivity to light it corresponds with the physiological “blind spot”.
The appearance of the optic disc can be used to determine the healthiness of the nerve itself.
Orbit
Bony socket containing eye & accessory organs
The Roof, The Floor, Medial Wall are very thin & easily damaged
