Eye anatomy and intro Flashcards
What forms the floor of the orbit?
Superior surface of the maxillary bone
What forms the medial wall of the orbit?
Paired maxillary and lacrimal bones and the singular ethmoid bone
What forms the anterior wall/thickest part of the orbit?
the zygomatic bone
What forms the posterior wall of the orbit?
the sphenoid bone
What bones make up the eye orbit?
sphenoid, zygomatic, maxillary, lacrimal, ethmoic
Describe the location of the optic foramen
Apex of the orbital pyramid. Near the posterior medial part of the orbit
What goes through the optic foramen?
Optic nerve. Ophthalmic artery. Sympathetic nerves
What passes through the superior orbital fissure?
branches of the cranial nerves that provide motor innervations for the extrinsic and intrinsic eye muscles and sensory innervations to the orbit and its contents.
What is the palpebral fissure?
Oval opening between the upper and lower eyelids
What is the canthus?
Where the upper and lower lids meet
What is a characteristic eye feature of Asians and chromosomal abnormalities (plica palpebronsalis)?
Epicanthic fold covers the medial canthus
What is the difference between an opthalmologist and an optometrist?
An optometrist is a Doctor of Optometry, an O.D. whereas an opthalmologist is a doctor of medicine. only ophthalmologists can truly diagnose and treat a wide range of eye diseases and disorders.
When should a patient contact an opthalmologist?
If a patient has a family history of eye disorders and may be suffering from some type of eye issue
When should a patient contact an optometrist?
if your patient are simply having difficulty seeing properly, chances are they should visit an optometrist for an eye exam
What defines the angle of the palpebral fissure and what is its common anatomical angle?
Line thru the lateral and medial canthus. Is usually horizontal
What angle is the palpebral fissure in downs syndrome?
has an upward outward slant
What are meibomian glands?
Sebaceous gland.Ducts open onto eyelids. Secretions enable airtight closure of the lids and prevent evaporation of tears
What is the fxn of the lacrimal glands?
serous secretions (tears)- lubrication reduces friction between the eyes and eyelid. protective-contains antibacterial enzyme lysoenzyme
What is the conjunctiva?
Thin mucus membrane, lines inner surface of both eyelids.
What are the two types of conjunctiva?
Palpebral conjunctiva (Lines the eyelids) and Bulbar (ocular)conjunctiva (covers the eyeball, is adjacent to eyeball)
What does the lateral rectus muscle do and what nerve controls it?
moves eye laterally. nerve VI (abducens)
What does the medial rectus muscle do and what nerve controls it?
moves eye medially. nerve III (oculomotor)
What does the superior rectus muscle do and what nerve controls it?
elevates eye and turns it medially. nerve III (oculomotor)
What does the inferior rectus muscle do and what nerve controls it?
depresses the eye and turns it medially. nerve III (oculomotor)
What does the inferior oblique muscle do and what nerve controls it?
elevates the eye and turns it laterally. nerve III (oculomotor)
What does the superior oblique muscle do and what nerve controls it?
depresses the eye and turns it laterally. nerve IV (trochlear)
What are the three distinct layers of the eye?
Sclera, Choroid or middle vascular layer, and Retina
What are the layers of the retina?
Neural retinal layers and Outer pigmented layer
What is the sclera?
Outer layer of the eyeball. Tough, opaque white fibrous layer. Maintains shape of the globe
What is the lamina cribrosa?
Posterior sclera where optic nerves pass though and exit in the retina
What is the fxn of the retina?
to receive visual images, analyze them and transmit this modified info to the brain
What are the three layers of the neural retina?
posterior layer, middle layer, and third layer
What does the posterior layer of the neural retina contain?
photoreceptors
What does the middle layer of the neural retina contain?
ganglion cells that communicate with photorecptors, receive impulses generated by the rod and cone cells
What does the third layer of the neural retina contain?
ganglionic neurons attached directly to the optic nerve.
What makes up the uvea?
iris, ciliary body, choroid
What is the iris and its fxn?
contains the radial (dilator) muscles of the eye. Also contains fibroblasts and melanocytes (Eye color)
What is the ciliary body and its fxn?
Smooth muscle. Contributes to alteration in lens shape and the production of aqueous humor
What does the cornea do?
Major part of refraction and focusing of vision
What is the substantia propria (stroma)?
part of the cornea that contains collagen bundles necessary for light transmission
Describe anterior cavity of the eyeball
fluid filled cavity. Divided into an anterior chamber and posterior chamber. Lens and cilliary body divide these
Describe the posterior cavity of the eyeball
also known as the vitreous body. Filled with a gel-like material.
Where is the anterior chamber of the eyeball located?
lies in front of the iris
Where is the posterior chamber of the eyeball located?
posterior to the iris and anterior to the lens
What fills the posterior cavity of the globe?
gel-like vitreous humor
What is the intraocular fluid?
fluid that fills the eye. Maintains sufficient pressure to keep eyeball distended
What are the two portions of the intraocular fluid?
aqueous humor and vitreous humor
Describe the aqueous humor
lies in front of the lens. Freely flowing fluid
Describe the vitreous humor
lies between posterior surface of the lens and the retina. Gelatinous mass
What regulates the total volume and pressure of the intraocular fluid?
the balance between the formation and reabsorption of aqueous humor
What produces the aqueous humor?
the ciliary body
Describe the flow of the aqueous humor
Through the pupil into anterior chamber. Then into the angle between the cornea and iris. Through meshwork of trabeculae. Enters Canal of Schlemm.
Empties into extraocular veins
What is the normal intraocular pressure?
12-20mmHg
What determines intraocular pressure?
resistance to outflow of aqueous humor from the anterior chamber into the canal of Schlemm (ie The amount leaving via the canal of Schlemm usually equals the inflow of fluid from the ciliary body)
What are the photoreceptors?
Rods (Black-white discrimination) and cones
Color discrimination
What is the macula and its fxn?
Yellow spot near the center of the retina.Acute and detailed vision. Composed entirely of cones
What is the fovea and its fxn?
Central portion of the macula. responsible for central vision: Straight-ahead vision which is necessary for any activity where visual detail is of primary importance.
What is peripheral vision?
The ability to see objects and movement outside of the direct line of vision. is a part of vision that occurs outside the very center of gaze
What is responsible for peripheral vision and where are they located?
Peripheral vision is the work of the rods, nerve cells located largely outside the macula of the retina.
What are causes of peripheral vision loss?
Migraine, Chronic closed-angle Glaucoma, Open-angle Glaucoma, Retinitis pigmentosa, Brain Tumor
Tertiary Syphilis
What is the optic disc?
The 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.
What is the color of a normal optic disc?
orange to pink
What is a pale disc and what is its significance on exam?
varies in color from a pale pink or orange color to white. A pale disc is an indication of a disease condition.
Why is the optic disc called the blind spot?
because there are no receptors in this part of the retina. This is where all of the axons of the ganglion cells exit the retina to form the optic nerve.
What is the choroid?
vascular layer of the uveal tract
What is the fxn of the choroid?
Melanocytes prevent the diffusion of light through out the wall of the optic globe. Pigmentation in these cells absorbs light in the eyeball and light penetrates the retina. This light-absorptive function prevents the scattering of light and is important for visual acuity.
