Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
102 Cards in this Set
- Front
- Back
What are the orbits?
|
Bony cavities in facial skeleton resembling quadrangular pyramids
|
|
How are the orbit axes related?
How are the optical axes related? |
-Orbit axes diverge @ 45 degrees
-Optic axes are parallel |
|
What is the function of the orbits?
|
To contain and protect the eyeballs and accessory visual structures.
|
|
What are the accessory visual structures?
|
-Eyelids
-Extraocular muscles -Neurovasculature -Orbital fascia -Conjunctiva/Lacrimal apparat. |
|
What is the function of orbital fat?
|
To fill any space not occupied by the eyeball or accessory visual structures, forming a matrix that supports them.
|
|
What are the general features of the pramidal orbit?
|
-Base
-Four walls -Apex |
|
What is the base made up of?
|
The orbital margin sourrounding the orbital opening.
|
|
What is the function of the base?
|
To reinforce the orbit margin, protect its contents, and provide attachmnet for orbital septum.
|
|
What is the orbital septum?
|
Interrupted fibrous sheet extending into the eyelids.
|
|
What forms the roof of the orbit?
|
The orbital part of the frontal bone.
|
|
What special feature of the frontal bone resides in the roof?
|
Fossa for the lacrimal gland - shallow depression for it.
|
|
What constitutes the medial wall of the orbit?
|
The ethmoid bone, along with fronta/lacrimal/sphenoid contributions.
|
|
What 2 indentations are found on the medial orbit wall?
|
-Fossa for lacrimal sac
-Lacrimal groove |
|
Why is the medial wall paper thin?
|
B/c the ethmoid bone is highly pneumatized
|
|
What forms the orbital floor?
|
Maxillary orbital plate
|
|
What important feature is found in the orbit floor maxilla?
|
Inferior orbital fissure
|
|
What forms the lateral orbit wall?
|
-Greater wing of sphenoid
-Zygomatic bone |
|
What is the apex of the orbit?
|
The optic canal.
|
|
Where is the widest part of the orbit?
|
At the equator of the eyeball
|
|
What lines the orbit bones?
|
Periorbita
|
|
What is the function of eyelids?
|
To protect the eyeballs and spread lacrimal fluid over them.
|
|
What covers the eyelids?
|
-Externally = skin
-Internally = palpebral conjunctiva |
|
What is palpebral conjunctiva?
|
a transparent mucous membrane that is reflected onto the eyeball too
|
|
What is the conjunctiva of the eyeball that is continuous with the palpebral conjunctiva?
|
Bulbar
|
|
What does the bulbar conjunctiva adhere to?
|
The cornea.
|
|
What is a conjunctival fornix?
|
A deep recess created where the palpebral conjunctiva reflects to form the bulbar.
|
|
what is the conjunctival sac?
|
The space formed between the palpebral and bulbar conjunctiva when the eyelid is closed.
|
|
What is the conjunctival sac called when the eyelid is open?
|
The palpebral fissure
|
|
What forms the 'skeleton' of the eyelids? What type of tissue?
|
Superior/inferior tarsi - connective tissue bands.
|
|
What secretory glands are found within the eyelids?
|
Tarsal glands - secrete lipid substance that's immiscible with tears; makes them spill onto cheeks when you cry.
|
|
What are the sebaceous glands associated w/ eyelashes called?
|
Cilia
|
|
What are the corners of the eyes called where the eyelids meet?
|
Med/Lat Palpebral commissures (kanthos -- acanthamoeba)
|
|
What are the medial/lateral palpebral ligaments?
|
Ligaments that attach the tarsi to orbit margins.
-orbic. oculi inserts on medial |
|
what is the orbital septum?
|
a weak membrane spanning from the tarsi to orbit margins; continuous with periosteum.
|
|
What 4 things does the lacrimal apparatus consist of?
|
1. Lacrimal glands
2. Lacrimal ducts 3. Lacrimal canaliculi 4. Nasolacrimal duct |
|
What do the lacrimal glands produce?
|
Lacrimal fluid - moistens and lubricates conjunctiva and cornea
|
|
What is lacrimal fluid made up of?
|
-Physiological H2O-based saline -Bacteriocidal lysozyme
-Dissolved O2 -Nutrients |
|
What do the lacrimal ducts do?
|
Convey lacrimal fluid to the conjunctival sac.
|
|
What are lacrimal canaliculi?
|
Small ducts that drain lacrimal fluid from the lacrimal lake to the lacrimal sac.
|
|
What is the lacrimal lake?
|
a triangular space at the medial eye angle where tears collect.
|
|
What is the lacrimal sac?
|
The upper portion of the nasolacrimal duct
|
|
What does the nasolacrimal duct exist for?
|
Conveying tears from the lacrimal duct to the inferior nasal meatus.
|
|
How does the levator palpebrae superioris interact with the lacrimal gland?
|
Separates it into superior (orbital) and inferior (palpebral) portions.
|
|
What are lacrimal puncta?
|
Small openings on the lacrimal papilla near medial angle of eye; when eye contracts tears drain into them to be carried to lacrimal sac.
|
|
What nerve stimulates lacrimal fluid production?
|
Parasympathetic fibers of CN VII
|
|
Where does lacrimal fluid initially get secreted?
|
From 8-12 excretory ducts in the lateral superior conjunctival fornix.
|
|
In what manner do eyelids come together when one blinks?
|
Lateral to medial; facilitates pushing of fluid from excretion site to drainage site.
|
|
What happens to tears ultimately?
|
They drain into the inferior nasal meatus, to nasopharynx, and get swallowed.
|
|
What type of nerves supply the lacrimal apparatus in general?
|
both sympathetic and parasymp.
|
|
What are the 2 components of loose connective tissue around the eyeball called?
|
Posterior: bulbar fascia
Anterior: bulbar conjunctiva (continuous w/ palpebral) |
|
What are the 3 layers of the eyeball proper? What does each consist of?
|
1. Fibrous = sclera + cornea
2. Vascular = choroid + ciliary body + iris 3. Inner = retina (optic/non) |
|
What is the sclera?
|
the tough, opaque part of the fibrous layer; covers the posterior 5/6 of the eye.
|
|
What is the sclera's function?
|
-Provides a skeletal structure - shape and resistance.
-Attachment site for muscles |
|
What is the cornea?
|
transparent fibrous coat that covers anterior 1/6 of eyeball
|
|
what's the difference between cornea and sclera?
|
The pattern of collagen in each, and degree of hydration.
|
|
What is another name for the vascular layer of the eyeball?
|
the uvea or uveal tract.
|
|
What does the uvea/vascular consist of again?
|
1. Choroid
2. Ciliary body 3. Iris |
|
What is the choroid?
|
Dark red-brown layer between sclera and retina; largest part of the vascular layer.
|
|
How does the ciliary body compare to the choroid?
|
Ciliary = muscle + vascular
Choroid = only vascular |
|
What is the function of the ciliary body?
|
Connects the choroid to the iris circumference.
|
|
How does the ciliary body affect the eyeball lens?
|
Contraction of its smooth muscle affects the thickness and thus focus of the lens.
|
|
What are ciliary processes and what do they do?
|
Folds on the internal ciliary body surface; secrete aqueous humor
|
|
What does aqueous humor fill?
|
Anterior and Posterior chambers of the eye
|
|
Where is the anterior chamber of the eye?
|
between the cornea and iris/pupil
|
|
Where is the posterior chamber of the eye?
|
Between the iris/pupil and the lens/ciliary body.
|
|
Where is the iris located?
|
Lies on top of anterior surface of the lens - literally!
|
|
What is the iris?
|
A thin contractile diaphragm w/ a central aperture
|
|
What is the central aperture in the iris called?
|
The pupil
|
|
What controls the size of the pupil?
|
The iris - 2 muscles that act on it
|
|
What are the 2 involuntary muscles controlling the iris?
|
1. Sphincter pupillae
2. Dilator pupillae |
|
What is the action of sphincter pupillae? What type of nerve supplies it?
|
Closes the pupil; makes things dark; parasympathetic
|
|
What is the action of dilator pupillae? What type of nerve?
|
Opens the pupil wide; makes things bright; sympathetic
|
|
What nerve innervates the pupillae muscles?
|
Oculomoter nerve CN III
|
|
When testing pupillary light reflex, what happens?
|
Shine a lite in one eye, but both pupils contract.
|
|
What does interruption of parasympathetic fibers to the pupillary muscles result in?
|
Unopposed constriction by sympathetic fibers, thus failure of pupils to close.
|
|
What does the inner layer of the eyball consist of?
|
The retina.
|
|
What are the 2 functional parts of the retina?
|
-Optic retina (sensitive to light)
-Non-visual retina |
|
What are the 2 parts of the optic retina?
|
-Neural layer (light sensitive)
-Pigment cell layer |
|
What does the pigment cell layer do?
|
reinforces lite-absorbing property of choroid to reduce light scatter in the eyeball.
|
|
What is the non-visual retina?
|
An anterior continuation of the pigment cell layer
|
|
What are the 2 parts of the non-visual retina, and what do they do?
|
-Ciliary part
-Iridial part Provide support to the ciliary body and posterior iris surface. |
|
What is the posterior part of the eyeball called?
|
the fundus
|
|
what is the optic disc?
|
A circular depressed area at the back of the eyeball where the optic nerve fibers and vessels enter.
|
|
What is another name for the optic disc, and why?
|
The blind spot - contains no photoreceptors.
|
|
What is the yellow spot just lateral to the optic disc?
|
Macula lutea.
|
|
What is the macula lutea's function?
|
To provide acuity of vision via special photoreceptor cones.
|
|
What area of the macula lutea provides the best acuity of vision?
|
Fovea centralis
|
|
What is the border between functional and nonvisual retina called?
|
Ora serrata - just behind ciliary body
|
|
What supplies the retina with blood?
|
Cones/rods of neural layer: capillary network of choroid
Other: central artery of retina (opthalmic branch) |
|
What 4 structures constitute the refractive media of the eyeball?
|
1. Cornea
2. Aqueous humor 3. Lens 4. Vitreous humor |
|
What innervates the cornea?
|
V1 - opthalmic branch
|
|
What encloses the lens of the eye?
|
a highly elastic capsule anchored by zonular fibers
|
|
What do the zonular fibers attach the lens to?
|
The ciliary body
|
|
What muscle varies the convexity of the lens?
|
The ciliary muscle
|
|
How is the ciliary muscle normally situated?
|
It stretches the lens fairly flat so the spherical shape is flat enough for far vision.
|
|
How does the lens change to accomodate near vision?
|
Parasympathic stimulation causes the smooth muscle to contract; as the sphincter like muscle tightens, the tension on the lens reduces making it rounder.
|
|
Where is the vitreous body?
|
In the posterior 4/5 of the eyeball.
|
|
What is the function of the vitreous humor?
|
Transmits light, holds the retina in place, and supports the lens.
|
|
What are the extraocular muscles? (7)
|
-Levator palpebrae superioris
-Recti (sup/inf/lat/med) -Sup/inf Obliques |
|
What are the distal attachments of levator palpebrae sup.?
|
-Skin of superior eyelid
-Deep lamina of superior tarsus |
|
What opposes levator palpebrae?
|
-Gravity
-Orbicularis oculi |
|
What is the function of the superior tarsal muscle?
|
Extra widening of eye during sympathetic response (Fright).
|