Flashcards in Eye Anatomy Deck (28)
What bones make up each Margin of the Orbit:
Superior- frontal bone
Inferior- zygomatic & maxillary
Lateral- zygomatic process of frontal bone
Medial- maxilla, lacrimal, frontal
What bones make up the walls of the orbit?
-posterior lateral wall
Roof-frontal and sphenoid
Posterior Lateral- zygomatic sphenoid
Floor- maxilla, zygomatic, palantine
Medial- ethmoid, lacrimal, frontal
Structures that enter the optic canal?
-central retinal vein
Structures that pass through the superior orbital fissure
- Occulomotor Nerve, Trochlear Nerve, Abducens Nerve
Lacrimal, frontal, and nasocilliary branches of opthalmic nerve
Sympathetic fibers of cavernous plexus
Live frankly to see absoultely no insult
Term that describes upper and lower eyelid
-function: protect and lubricate the eyes
What is the tarsal plate?
What is the canthus?
-what are some deformalities of the canthus?
Line that runs through the canthus?
-fibrous layer that gives the lids shape, strength, and place for muscle attachment
-canthus is where upper and lower lids meet, there are two; lateral and medial canthus
- palpebral fissure, ususally runs horizontally.
*upward slant = downs syndrome
*epicanthic fold- covers the medial canthus = chromosome abnormalities. turners, fetal alcohol syndrome
What are meibomian glands? Where are these located?
-these glands lie underneath and within the tarsal plate
-these glands secret oil, secretions enable airtight closure of the lids.
What is a Chalazion?
-back up of fluid/oil from meibomian glands that causes a lump in the eyelid near the eyelashes, they are nontender, non-red, and removed via I&D.
How is a stye different from Chalazion?
Stye= like pimple, red, tender, anywhere on eyelid
Chalazion= lump, non red, non tender, near eyelash line.
Muscles of the Eyelid, function, and Cranial Nerve
Orbicularis oculi- closes the eyelid, CN VII (hook)
Levator Palpebrae- opens the eyelid, CN III (pillars)
-type of secretions
-function of secretion
-where do these secretions drain
- located within eyelid and conjunctive in the superior lateral aspect of eye.
-serous secretions= tears
-tears clean and lubricate eye, antibacterial enzyme lysozyme.
-drain into the lacrimal punctum (little holes near the medial canthus) down into nose near inferior turbinate
Describe the conjunctiva
Describe the borders of the conjunctiva
What are the 2 types of conjunctiva?
-thin mucus membrane with lines with blood vessels, lines inner surface of both eyelids
-starts at the edge of the cornea at the limbus and flows back behind the eye, loops forward, and forms inside the surface of the eyelids.
- Palpebral conjunctiva = lines eyelids
-Ocular conjunctiva= covers eyeball
Name each layer of the eyeball and what comprises each.
----sclera and cornea
----choroid, ciliary body, and iris
-Internal or Neural Tunic
----retina (contain neural retinal layer and outer pigmented layer)
Describe the Sclera
-outer layer of the eyeball
-tough, opaque white fibrous layer
-maintains the shape of the globe
-continuous and connects to the transparent cornea anteriorly>>> cornea is clear because the (stuff) is more orgnized
-posteriorly continuous with the dura mater that surrounds the optic nerve
Describe the Cornea
-Convex clear front surface of the eye
-provides majority of eyes refractive power
-avascular, gets nutrients from tears and aqueous fluid as well as peripheral blood vessels
--stroma (makes up 90% of cornea, can form a scar)
--endothelium (regulates fluid that goes into cornea too much liquid can make vision blurry and require a corneal transplant)
Describe the Choroid
-one of the most vascular tissues in the whole body
-melanocytes prevent the diffusion of light through out the wall of the optic globe
-supplies nutrients and oxygen to the retina
Describe the Ciliary body
-located immediately anteriorly to the choroid
-contains smooth ciliary muscles (that control shape of the lens
-secretory function (contributes to the production of aqueous humor)
Describe the Iris
-most anterior portion (of the vascular tunic)
-composed of: 2 layers of pigment forming cells and two groups of smooth muscle fibers (sphincter pupillae muscle and dilator pupillae muscle) (controls amount of light that enters the pupil)
-center of the iris is the pupil
Describe the Retina
-recieve visual images
-analyze them and transmit them to the brain
-macula lutea (contains fovea centralis- mainly cones)
Neural retina layer- photo receptors (rods and cones) and neurons. absorb light rays and convert them into nerve signals transmitted to the brain
Pigmented layer- immediately interal to choroid. absorb light rays that pass through the neural layer and provides Vit. A for photo recetors
where is this located?
what are the 3 layers
what are zonules?
- sits behind the iris
capsule: thin like saran wrap and holds lens in place.
cortex: middle layer
nucleus: hard inner layer
Zonules hold capsule in place, they are suspensory ligaments that are connected to ciliary body
-dividied into two cavities;
what the chambers within each cavity?
ANTERIOR CAVITY; divided into ANTERIOR CHAMBER, lies between cornea and iris containing aqueous humor, and POSTERIOR CHAMBER, lies between iris and lens containing aqueous humor.
Posterior cavity: vitreous chamber, extends from lense back to retina containing vitreous humor.
Aqueous humor flow from ciliary processes & function
aqueous humor is a filtrate of blood plasma produced by ciliary processes and secreted into posterior chamber.
From posterior chamber it flows through pupil into anterior chamber. Fluid is continually reablsorbed into vascular space called the scleral venous sinus.
function- provides nutrients and oxygen to lens and cornea
-what fluid comprises this chamber?
-fluid produced by..?
-function of fluid in chamber
-- vitreous fluid which is gelatinous
-produced by cells in the non-pigmented portion of the ciliary body
-fluid fills space from lens to posterior retina, helps maintain eye shape and supports the retina.
What are the 6 extrinsic eye muscles, action, and controlling cranial nerve?
Lateral rectus- moves eye laterally, CN VI (abducens) (LR6)
Medial rectus- moves eye medially, CN III (occulomotor)
Superior Rectus- elevates eye and turns it medially III (occulomotor)
Inferior rectus- depresses eye and turns medially, CN III (Occulomotor)
Inferior oblique -elevates eye and turns it laterally, CN III (occulomotor)
Superior Oblique- depresses eye and turns it laterally, CN IV (trochlear) (SO4)
Contraction of ciliary muscle leads to what?
-stretches the choroid releasing tension on zonules making the lens more round and puffy=accomodation.
Relaxation of the ciliary muscle leads to what?
-choroid pulls back on the ciliary body thereby tightening the zonules and lengthens/flattens the lens out, helps see far distances.
Does the lens get hard as we age? What effects does this have?
yes, as we age they dont have the pliability.
Firm= cant see up close
Squishy= can see up close, not distances