Anatomy of the eye Flashcards
3 layers of eyeball
Fibrous (collagen, complete coat)
Vscular
Sensoary
Whchh nerve of the eyeball?
Optic nerve (cranial nerve II)
2 parts of the fibrous coat
-Sclera (opaque, attatchment for eye muscles)
-Cornea (opaque - fibres in the same direction and is transparrent)
3 parts of the vascular part
-iris (changes the amount of light let through),
-ciliary body (secretes aqueous humor and suspends the lens)
-Choroid ( supplies blood to the outer layers of the retina)
why is cornea transparent?
Because all the collagen fibres are alligned in the same direction, to let light through)
What is the retina?
the sensory section of the eye, contains light sensitive rods and cones that allow us to see
Post vs anterior segment and filled with
Posterior segment is veerything behind the lens, flled with vitreous Humor (VH)
Anterior segment is everything infront of the lens and filled with aqueous humor (AH)
What are zonules
the very thin strings attaching the lens to the ciliary muscle
Anterior vs posterior chamber of the anterior segment of the eye
anterior chamber is the section in front of the iris
post. chamber is infront of the lens but behind the iris
What is the angle of the anterior chamber
the angle around the iris to Schlemms canal (where all the aqueous humor drains) on the sclera/cornea junctiony kinda
What is the pathway of the aqeous humour
from the cliary body (where it’s produced) around the iris and drains in Schlemm’s canal
How many bones make up the orbit? WHich bones are they?
7
Frntal,
zygomatic,
maxillary
(pallatine)
Sphlenoid
lacrimal
ethmoid
What are the foramen of the eye?
OPtic foramen
Superior Orbital fissure
Inferior Orbital fissue
Why are the inferior and medial orbital walls weaker?
Because of the sinuses
AP legth of eyeball/AP length of orbit
eyeball = 24mm
Orbit = 40mm
What is the role of the fat?
cushions and protects
2 conditions that affect the fat on th eeyeball
Starvation - last fat to go so sunken eyeballs menas that theyre at a late stage
Thyroid eye disorder - staring like look, too much fat
WHat is the conjunctiva?
mucous membrane undreneath the eyelid, loops back over to the sclera but doesn’t cover the cornea
What is the tarsal plate? What mebibomian glands do what?
Hard plat in the eyelid that helps the eye to keep its shape and contains the Meibomian glands which secrete oily substance which helps the tear film not to dry out
WHere is the fornix?
It is the mucous membrane (conjunctva) at the part it turns back on itself
Does he conjunctiva cover the cornea?
NO!!!
What does the lacrimal gland do?
Secretes tears/fluid over the eye to lubricate
Extrinsic vs intrinsic muscles of the eye
Extrinsic muscles - on the outside of the eye and help with eye movement
Intrinsic muscles - within and help change lens shape etc
What are the 3 intrinsic muscles of the eye? What do they do?
Cilliaris - focusses on near objects)
Constrictor - circular muscle , constricts
Dilator - dilates duh
If it begins with C, its cranial nerve 3 (parasympathetic innervation)
Dilator supplied by sympathetic plexuss (around the blood vessels)
What are the 6 extrinsic ocular muscles? (4 and 2)
4 retus’s (straigh muscles)
Superior rectus, inferiot rectus, lateral rectus and medial rectus.
2 oblique - superior and inferior
What does the lps do?
levator palpable superioris - opens the eyelid. Orbicularis oculi closes the eye
Innervation of the muscles of the eye
Superior orbital = trochlea (the superior orbital has a trochlear (pully thing)
Lateral rectus = an abductor = Abducent nerve
Everything else = Oculomotor (III) nerve
4 cranial nerve that go to the orbit
trochlear (IV)
abducent (VI)
oculomotor (III)
optic (II)
Entry of cranial nerves in the orbit
Optic (II) = Optic foramen
Superior orbital fissure = Abducent (VI), Trochlear (IV) and Oculomotor (III)
General sensory nerve of the face
Trigeminal
How does CN V 1 and V2 into the ee
V1 is sensory above, V2 is sensory below
Arterial supply of the orbit
Opthalmic artery (banch of internal carotid)
Central retinal artery - enters where? Branch of what?
2nd branch of opthalmic artery, enters with the optic nerve
Branches 3,4,5 do what?
Supply the outer retina (post. part of Choroid)
branch 6 - lomh posterorior artery supplies what?
anterior choroid, ciliary body and iris
7,8 what about 9
7,8 are the anterior and posterior ethmoidal arteries
9 = muscular arteries
What are the supplies of the inner and outer retinas
inner retina = 2nd branch (central retinal artery)
outer retina = short posterior ciliary arteries
qudrants of the retina
Nasal and temporal superior and inferior around the optic blind spot (where the optic nerve comes in)
What are thicker on a fundus picture, arteries or veins?
veins (more blood in)
Venous drainage of the eye
Superior and inferior opthalmic veins drain into the cavernous sinus
What does the eye drvelop from?
ectoderm (Neural tube)
What froms the optic vesicles?
from dienecephalic part of neural tube
What thickens to form the lens placode? What does the that then form?
Optic vesicles thicken to fromt he lens placode, which then push in to form the optic cup
What is formed from the a)Surface ectoderm b) Mesenchyme and c) Les fibres
a) eyelids, conjunctiva, corneal epithelium
b) choroid, stroma or cornea, sclera and extraocular muscles
c) epithelium of lens vesicle and later loose their nuclei
