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Flashcards in Anatomy Deck (101)
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What is the superior margin of the eye formed by?

frontal bone


What is the lateral margin of the eye formed by?

zygomatic process of frontal bone


What is the inferior margin of the eye formed by?

zygomatic and maxillary bones


What is the medial margin of the eye formed by?

maxilla, lacrimal, frontal bones


What bones form the roof of the orbit?

frontal and sphenoid bones
(lesser wing of sphenoid bone and orbital plate of frontal bone)


What bones for the posterior lateral wall of the orbit?

zygomatic and sphenoid
(zygomatic process of the frontal bone, greater wing of sphenoid bone, orbital surface of zygomatic bone)


What bones from the floor of the orbit?

maxilla, zygomatic, palatine
(orbital process of palatine bone, orbital surface of maxillary bone, zygomatic bone)


What bones form the medial wall of the orbit?

ethmoid, lacrimal, frontal
(sphenoid body, orbital plate of ethmoid bone, frontal process of maxilla, lacrimal bone)


Where is the superior orbital fissure located and what structures pass through it?

-located: between the lesser and greater wings of the sphenoid bone
-superior and inferior divisions of the oculomotor nerve (III)
-lacrimal, frontal, nasociliary branches of ophthalmic nerve
-trochlear nerve (IV)
-abducens nerve (VI)
-superior and inferior divisions of ophthalmic vein
-sympathetic fibers from cavernous plexus


Where is the optic foramen (canal) located and what are the structures that enter the optic canal?

Located: apex of the orbit and lies within the sphenoid bone
Structures that enter: optic nerve, ophthalmic artery, central retinal vein


What are the nerves that pass through the orbital fissure?
(lazy french tarts sit nakedly in anticipation)

lacrimal, frontal, abducens, inferior division of oculomotor nerve, trochlear, superior division of oculomotor nerve, nasociliary


Medial rectus

Nerve: occulomotor (III)
Function: moves eye medially (nasally)
Deficit: eye down and out b/c of unopposed action of lateral rectus and superior oblique


Lateral rectus

Nerve: Abducens (VI)
Function: moves the eye laterally (temporally)
Deficit: eye cannot look laterally


Superior rectus

Nerve: occulomotor (III)
Function: ELEVATES eye and rolls it UPward
Deficit: weakness of upward gaze


Inferior rectus

Nerve: occulomotor
Function: DEPRESSES the eye and rolls it DOWNward
Deficit: weakness of downward gaze


Superior oblique

Nerve: Trochlear (IV)
Function: turns eye DOWNward and LATERALLY
Deficit: vertical diplopia, head tilt (compensation for imbalance of rotation)


Inferior oblique

Nerve: occulomotor (III)
Function: ELEVATES eye and turns LATERALLY
Deficit: vertical diplopia, head tilt


What is the function of the orbicularis oculi muscle? What is it innervated by?

Function: closes eyelids
Innervated: facial nerve (VII)


What is the function of the levator palpebrae muscle? What is it innervated by?

Function: opens the eye
Innervated: Occulomotor (III)


What is cranial nerve I?
Sensory, motor, or both?
What foramen does it exit?
What is its function?

cribiform plate on ethmoid bone


What is cranial nerve II?
Sensory, motor, or both?
What foramen does it exit?
What is its function?

optical canal (foramen)


What is cranial nerve III?
Sensory, motor or both?
What foramen does it exit?
What is its function?

superior orbital fissure
innervates 4 eye muscles:
medial rectus -- turns eye medially
superior rectus -- elevates eye and rolls upward
Inferior rectus -- depresses eye and rolls downward
inferior oblique -- elevates eye and turns laterally


What is cranial nerve IV?
Sensory, motor, or both?
What foramen does it exit?
What is its function?

superior orbital fissure
innervates the superior oblique muscle--moves eye down and lateral


What is cranial nerve VI?
Sensory, motor, or both?
What foramen does it exit?
What is its function?

superior orbital fissure
innervates the lateral rectus muscle-- moves eye laterally


What are the upper and lower eyelids termed?
What is their function?

to protect and lubricate the eyes


What is the tarsal plate? Where is it located?

--fibrous layer that gives the lids shape, strength, and place for muscle attachment
--located in the posterior lamella


What is the canthus

where the upper and lower lids meet
(lateral and medial canthus)


With downs syndrome, what line has an upward, outward slant? (also see with turners syndrome and fetal alcohol syndrome)
Aslo a characteristic of asians and certain chromosomal abnormalities.

line through the lateral and medial cants defines the angle of the palpebral fissure, which is usually horizontal


What and where are meibomian glands?
What is function?
What occurs with infection?

-Like underneath AND within the tarsal plate
-ducts open onto the eyelids and help eye become lubricated, secrete oil, and help tears fro escaping too quickly
-secretions enable airtight closure of the lids
-glands can become infected (Chalazion)


What is a chalazion?
Where does it occur?
What is the difference b/w this and a stye?

-infected miebomian gland
-occurs IN the tarsal plate, NOT painful
-stye occurs closer to the eyelashes, painful, and more superficial


Where are the lacrimal glands located?
What is their function?
What is contained in tears?
Where do the tears drain?

-located within the eyelid and conjunctiva
-function: serous secretions (TEARS)
tears clean and lubricated the eye
tears are antibacterial enzyme lysozyme (dissolves outer layer coating of certain bacteria)
tears also contain: mucin, lipids, K+, Na+ and gulcose
-tears drain into the lacrimal puncture


What occurs with bells palsy patients?

patients have a hard time closing their eye on affected side, creating a lot of exposure problems
CN VII closes eye and innervates the orbicularis oculi muscle
remember that bells palsy affects CN VII (facial)


Where does the levator palpebrae muscle attach? What innervates it? What occurs with nerve palsy?

attaches: tarsal plate
innervated by: CNIII (occulomotor)
CN III palsy: tonic eyelid, very low eye
Remember that CN II helps to pull eye open


What is the path of tears as they are made from when they are drained?

lacrimal gland
ducts to eye
superior or inferior puncta (punctum)
superior or inferior lacrimal canaliculi
lacrimal sac
nasolacrimal duct
inferior turbinate
inferior meatus (lies underneath inferior turbinate)


What are the differences between the sclera and cornea?

--continuous and both made of same material
--cornea is clear because of differences in collagen arrangement
--cornea is more dehydrated in comparison with sclera


What is another name for choroid layer? What is its function?

-to provide vasculature to the retina


What is the conjunctiva, what are the two types of conjunctiva and where are they found? What are they sensitive to?

-thin mucous membrane that lines the inner surface of both eyelids
-both start behind edge of cornea (limbus) and flows back behind the eye and forms inside surface of eyelids
-two times: palpebral conjunctiva = lines the eyelids
ocular conjunctiva = covers the eyeball
-sensitive to: irritation and inflammation


What are the three layers of the eye and what is contained within those layers?

fibrous tunic: sclera, cornea
vascular tunic: ciliary body, choroid (urea), iris
neural or internal tunic: retina
a. neural retinal layer
b. outer pigmented layer


What is the cornea and what does it do?

-convex clear front surface of eye that provides majority of eyes refractive power


What are the layers of the cornea and what are characteristics of each?
(5 layers)
remember that cornea is part of fibrous tunic

epithelium = most abrasions occur here, usually heal w/o scarring
bowmans =
stroma = 9% of corneal thickness-- if injured, DO scar
desmemets membrane =
endothelium = 1 cell layer thick, regulates fluid that gets into cornea


What is important to remember about the endothelial layer of the cornea?

regulates fluid into cornea (like a pump)
--remember cornea needs to stay drier, therefore diseases that cause damage to endothelium cause edema and blurry vision
ENDOTHELIAL cells DO NOT regenerate. If cells get injured, they die and others get larger to compensate. They eventually get so large that edema occurs and pt needs corneal transplant


The sclera is part of the fibrous tunic. What are the characteristics of the sclera?

-outer layer of eyeball
-tough, opaque white fibrous layer
-maintains shape of globe
-continuous and connects to TRANSPARENT cornea anteriorly (connects at limbus)
-posteriorly, continuous with dura mater that surrounds optic nerve


Where are keratocytes located?

within the stroma layer of the cornea which remember is part of the fibrous tunic


What is the choroid layer part of? What is its function?

-part of: vascular layer (middle layer)
--one of the most vascular tissues in entire body
-supplies blood to retina
-melanocytes prevent the diffusion of light throughout the wall of the optic globe (absorbs all of remaining light so extra light can be focused on the retina so it can focus on the image


What layer is the ciliary body located in? What is the function and characteristics of the ciliary body?
Remember that the ciliary body is a muscle, continuous with the iris.

located: vascular tunic immediately anteriorly to the choroid
-contains smooth ciliary muscles that control the shape of the lens
-attached to the lens via zonules (360 degrees), ciliary muscles contract, lens gets more round = see up close
-secretory function which contributes to the production of aqueous humor


What layer if the iris located in?
What is the iris composed of?
What is at the center of the iris?

located: vascular tunic, most anterior portion
composed of: 2 layers of pigment forming cells
2 groups of smooth muscle fibers
sphincter pupillae muscle
dilatory pupillae muscle
Center: iris


What does the iris control?

the amount of light that hits the retina


What is makes up the inner tunic?



The retina makes up the inner tunic. What is its function and what are the components?

function: receive visual images, analyze them and send them to the brain
components: neural retinal layer AND pigmented layer
retina contains: optic disc, macula lute with fovea centralis


Where is the neural layer of the retina located? What is contained there and what is its function?

located within retina, within the inner tunic
contains: photo receptors and associated neurons that absorb light rays and convert them into nerve signals transmitted to the brain
contains: rods and cones


Where is the pigmented layer of the retina located and what is its function?

located in the inner tunic, within retina, immediately internal to choroid
function: absorb light rays that pass through neural layer
-provide vitamin A for photoreceptor cells


Where are rods located and what do they do?

located in retinal region, cannot distinguish color, poor at sharp vision


Where are cones located and what do they do?

primarily located in the fovea
cones are responsible for sharpness and color recognition


Where is the lens located? What are its 3 layers? What holds it in place?

located: behind iris
layers: capsule, cortex, nucleus
suspensory ligaments, zonules, hold capsule in place by attaching it to the ciliary body


What are the two cavities of the eyeball and what do they include?

anterior cavity: anterior chamber, posterior chamber
posterior cavity: vitreous chamber


What are the three chambers of the eyeball and where are they located and what is in those chambers?

-Anterior chamber: lies between cornea and iris, contains aqueous humor
-posterior chamber: lies between iris and lens, contains aqueous humor
-vitreous chamber: extends from lens back to retina, contains vitreous humor


What does the anterior and posterior chamber (anterior cavity) contain as far as fluid and where is it made? How is it filtered and what is the route it takes? What does it provide to the eye?

-contains aqueous humor that is a filtrate of blood plasma produced by the ciliary processes
-secreted first in posterior chamber, then flows through pupil into anterior chamber
-aqueous fluid is continually resorbed into vascular space called scleral venous sinus
-Provides: nutrients and O2 to the lens and cornea


What does the posterior cavity contain? What is its function?

-contains vitreous fluid, a transparent gelatinous fluid that is produced by cells in the non-pigmented portion of the ciliary body
-fills the space from lens to posterior retina
-helps to maintain eye shape
supports the retina


Superior oblique
O, I, N, A

o: sphenoid bone
i: sclera deep to superior rectus muscle
n: trochlear (IV)
a: abducts (lateral) and down (depresses)


Inferior oblique
O, I, N, A

O: anterior part of orbital floor
I: sclera deep to lateral rectus muslce
N:oculomotor (III)
A: elevates, laterally (abducts) rotates eye


Superior rectus
O, I, N, A

O: common tendinous ring
I: sclera behind the corneoscleral junction
N: oculomotor (III)
A: elevates, rolls eye upward


Inferior rectus
O, I, N, A

O: common tendinous ring
I: sclera behind corneoscleral junction
N: oculomotor (III)
A: down (depresses) eye, rolls eye downward


Medial rectus
O, I, N, A

O: common tendinous ring
I: sclera behind corneoscleral junction
N: oculomotor (III)
A: adducts eye (moves eye medially)


Lateral rectus
O, I, N, A

O: common tendinous ring
I: sclera behind corneoscleral junction
N: abducent (VI)
A: abducts eye (moves eye laterally)


What does the tear film contain?

water, oil, mucus


What are the sphincter pupillae muscles called? Where are they located? What do they do? When is it stimulaed by the ANS to contract?

Called: circular muscle, sphincter muscles
located: muscles of the iris
function:constrict the pupil
contracts: close vision and bright light


What are the dilator papillae muscles called? Where are they located? What do they do? When is it stimulated by the ANS to contract?

called: radial muscle
Located: muscles of the iris
Function: dilate the pupil
contracts: distant vision and dim light


What is accommodation?

the process in which the ciliary muscles contract, thereby relaxing tension on the zonules, allowing the lens to assume more of a spherical shape thus enabling one to focus closer on an object


Stimulation of what branch of ANS excites the pupillary sphincter muscles? What does this cause?

causes: miosis = decreases pupillary aperature


Stimulation of the sympathetic nervous system does what to the pupil?

dilates, or Mydriasis


What is mydriasis?

sympathetic stimulation that dilates pupil


What is miosis?

stimulation of the parasymphathetic never excites the pupillary sphincter thereby decreasing the pupillary aperature


With a direct response, the pupil should constrict. What causes this response to become impaired? (4 things)

lesions of the ipsilateral:
-optic nerve
-pretectal area
-parasympathetic traveling in CNIII
or the pupillary constrictor muscle of the iris (remember this is parasympathetic and is circular muscle)


With an consensual response, the contralateral pupil should constrict. What causes this to become impaired? (4 things)

lesions of the contralateral:
-optic nerve
pretectal area
lesions of the ipsilateral:
parasympathetics traveling in CN III
or the pupillary constrictor muscle of the iris (circular muscle)


When is accommodation impaired?
(accommodation is response to looking at something moving toward the eye)

lesions of the:
-ipsilateral optic nerve
-ipsilateral parasympathetics traveling in CN III
-pupillary constrictor muscle
-bilateral lesions of the pathways from the optic tracts to the visual cortex


Testing direct response in right eye and pupil doesn't constrict. Test consensual in right eye, and left pupil constricts. Then test direct in left eye and left constricts. Consensual on left side, right eye doest constrict. Where is the lesion?

Right side CN III


Test direct and consensual response in right eye first, neither eye responds. Then test left eye for direct and consensual response. Left eye is direct and consensual. Where is the lesion?

Right side CN II
(a right CN II lesion would lead to no pupillary constriction of either eye if light is shined in the right eye b/c CN II does not transmit the afferent information)


What are diseases that can cause blockage of the pupillary reflexes?

-CNS syphilis


What is an afferent pupillary defect?

decreased direct response cause by decreased visual function in one eye


How do you test the afferent pupillary defect? How does the test work?

Swinging flashlight test
works: light is moved back and forth every 2-3 seconds from normal to affected eye. Affected eye DILATES in response to light because the contralateral eye is dilating and the CN II in the affected eye isn't working properly, so it still receives signals from the unaffected eyes CN II through CN III (does same thing as non affected eye because it gets signals from the CN III)


What is hippus? What should it NOT be confused with?

-hippus is brief oscillations of pupillary size that occur normally in response to light
-should NOT be confused with afferent pupillary defect


What is conjugate gaze?

the use of both eye to look steadily in one direction


describe the characteristics of the lens.

biconvex body (more convex on posterior side)


What causes the lens to flatten?
(what part of ANS, what muscle affected)

Sympathetic input RELAXES the ciliary muscles
TIGHTENS the ciliary zonules
FLATTENS the lens
used for distant vision


What causes the lens to bulge?
(what part of ANS, what muscles affected)

Parasympathetic input CONTRACTS the ciliary muscles
LOOSENS the ciliary zonules
used for near vision


The ciliary muscle is controlled almost entirely by parasympathetic nerve signals transmitted to the eye through the third cranial nerve. What is the role of the sympathetic nervous system in accommodation?

Symp stimulation: plays only a minimal role on affecting the ciliary muscle and accommodation
-plays HUGE role in fight or flight however, but in normal accommodation, plays ALMOST NO ROLE


If the lens becomes more spherical (as in accommodation), is there an increased or decreased refractive power?

INCREASED refractive power
-gives ability to focus on NEARER objects


What is emmetropia?
What is the state of the ciliary muscles?
What can be seen clearly?
What must the eye do to see objects at close range?

normal vision
-when parallel light rays from distant objects are in sharp focus on the retina WHEN THE CILIARY MUSCLE IS COMPLETELY RELAXED
-distant objects can be seen clearly
-eye must contract ciliary muscle for objects at close range


What is prebyopia?
What occurs?

(old eyes)
lens grows thicker and larger, lens becomes less elastic, ability of lens to change shape decreases, power of accommodation decreases to ALMOST 0


What is hyperopia?
What is the mechanism?

-farsightedness (see far objects best)
-eyeball is too short so focal point is BEHIND the retina
-have trouble seeing objects that are up close


What is myopia?
What is the mechanism?

-eyeball is too long, so focal point in front of the retina
-CANNOT relax the CILIARY muscle any more to extend the focal point back any further
--REMEMBER THAT IN RELAXATION of the ciliary muscle, you end up tightening the zonules, making the lens thinner
-when object gets close enough, finally image can be focused


What do rods see?
Where are they located?
How many nerve cells do they synapse with?

-black and white
-lie in periphery
-thousands of rods may converge on a single ganglion cell = poorer visual acuity than the cones, but more sensitive to dim light


What do cones see?
Where are they located?
How many nerve cells do they synapse with?

-foveal area of retina, region in the center of the retina with the highest visual acuity
-almost a 1-1 connection with bipolar cells and ganglion cells


What are the three types of cones?

blue, green, red


What is the most common color blindness?



Trace the path of aqueous fluid from where its made in the ciliary processes to the exit in the canal of schlemm.

-ciliary body makes aqueous humor
-flows through the pupil into anterior chamber
-then through the angle between the cornea and iris
-through a meshwork of trabeculae
-then enters the canal of scheme
-finally empties into extraocular veins


Pressure in the normal eye remains constant. How is pressure determined?

pressure determined mainly by RESISTANCE to outflow of aqueous humor from the anterior chamber into the canal of scheme
-the amount leaving via the canal of schlemm usually equals the inflow of fluid from the ciliary body


Glaucoma is one of the most common causes of blindness. What causes it?

intraocular pressure become pathologically high and in most cases results from increased resistance to fluid outflow through the trabecular spaces into the canal of schlemm


What does OD stand for?



What does OS stand for?



What does OU stand for?