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Anatomy of The Eye

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INTRODUCTION

The Eye is theThe Eye is the

organ of vision.organ of vision.

Composed of :Composed of :

1.1. Eyeba.Eyeba.

2.2. The adne!a.The adne!a.

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T#E $O%ITION

In the $redatory spe&ies:In the $redatory spe&ies:

have set 'e for'ardhave set 'e for'ard

In #erbivores (In #erbivores (

R)minant and rabbits:R)minant and rabbits:

have eyes more aterayhave eyes more aterayto have 'ide area ofto have 'ide area of

visionvision

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Terminoogy of the eye

CorneaCornea: the transparent: the transparentpart of the eyeba .part of the eyeba .

Anterior poleAnterior pole: the highest: the highest

point on &ornea .point on &ornea .

Posterior polePosterior pole: the: the

highest point on posteriorhighest point on posterior

s)rfa&e .s)rfa&e .

Optic axisOptic axis: the straight: the straightine passing thro)gh bothine passing thro)gh both

poespoes

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The Eyeba

EquatoEquator :an imaginary ine abo)tr :an imaginary ine abo)tthe eyeba( 'hi&h is the e,)idistantthe eyeba( 'hi&h is the e,)idistantfrom the poes.from the poes.

MeridianMeridian: is one of many ines: is one of many inespassing from poe to poe thatpassing from poe to poe thatinterse&ts the e,)ator at right anges.interse&ts the e,)ator at right anges.

- Optic nerveOptic nerve:eaves the:eaves the

eyeba sighty ventra toeyeba sighty ventra tothe posterior poethe posterior poe

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Eyeba

The three t)ni&s are:The three t)ni&s are:

I/I/ An external fibrous tunicAn external fibrous tunic

II- A middle vascular tunicII- A middle vascular tunic

III/III/ An internal tunicAn internal tunic

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EyebaThe three t)ni&s are:The three t)ni&s are:

I.I. An external fibrous tunic:An external fibrous tunic: that gives form to and prote&ts thethat gives form to and prote&ts theeyeba its the ony &ompete t)ni&.eyeba its the ony &ompete t)ni&.

II.II. A middle vascular tunic:A middle vascular tunic:that &onsist argeythat &onsist argey

of bood vesses and smooth m)s&eof bood vesses and smooth m)s&e

&on&erned 'ith the n)trition of the eyeba and&on&erned 'ith the n)trition of the eyeba and

the reg)ation of the shape of the ens and si3e ofthe reg)ation of the shape of the ens and si3e ofp)pi.p)pi.

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Eyeba

III.III. An internal tunic:An internal tunic:that &onsists argeythat &onsists argey

of nervo)s tiss)eof nervo)s tiss)e

&on&erned 'ith vision and transation of&on&erned 'ith vision and transation of

vis)a stim)i into nerve imp)ses forvis)a stim)i into nerve imp)ses for

interpretation by the brain.interpretation by the brain.

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Te !ibrous Tunic

It &onsists of theIt &onsists of the sclerasclera and theand the cornea"cornea"

'hi&h meet at the'hi&h meet at the limbus.limbus.

#. Te sclera#. Te sclera is the opa,)e posterior part ofis the opa,)e posterior part of

the fibro)s t)ni& and &onsists of a dense fetthe fibro)s t)ni& and &onsists of a dense fet

'or6 of &oageno)s and easti& fibers and is'or6 of &oageno)s and easti& fibers and is

generay 'hite b)t in some spe&ies itgeneray 'hite b)t in some spe&ies it&ontain pigment &es&ontain pigment &es

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Te fibrous tunic

Te corneaTe corneaforms abo)t one ,)arter of theforms abo)t one ,)arter of the

fibro)s t)ni& and b)ges for'ard. It isfibro)s t)ni& and b)ges for'ard. It is

&omposed off dense &onne&tive tiss)e&omposed off dense &onne&tive tiss)earranged in amear form .arranged in amear form .

The &ornea doesnt &ontain bood vessesThe &ornea doesnt &ontain bood vesses

n)trients for its &es permeate from vessesn)trients for its &es permeate from vessesin the imb)s or are &arried to it its s)rfa&ein the imb)s or are &arried to it its s)rfa&e

in the a&rima f)id and a,)eo)s h)mor .in the a&rima f)id and a,)eo)s h)mor .

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The vas&)ar T)ni& 8)vea9

Deep to the s&era( 'hi&h it &omposed ofDeep to the s&era( 'hi&h it &omposed of

three 3ones .three 3ones .

#$ Te coroids:#$ Te coroids: ies on the s&era from theies on the s&era from the

opti& nerve to the imb)s and &ontains aopti& nerve to the imb)s and &ontains a

dense net'or6 of bood vesses embeddeddense net'or6 of bood vesses embedded

in heaviy pigmented &onne&tive tiss)ein heaviy pigmented &onne&tive tiss)e

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In the dorsa part of the f)nd)s the &horoids forms &oored(In the dorsa part of the f)nd)s the &horoids forms &oored(ight/refe&ting area 6no'n asight/refe&ting area 6no'n as tapetum lucidumtapetum lucidum is avas&)ar ayer 8&e)ar in the &arnivores( fibro)s inis avas&)ar ayer 8&e)ar in the &arnivores( fibro)s in

r)minants and horses9 bet'een the &apiaries and ther)minants and horses9 bet'een the &apiaries and thevesses.vesses.

The tapet)m ma6es the eyes of animas shine 'hen theyThe tapet)m ma6es the eyes of animas shine 'hen theyoo6 to'ard the ight.oo6 to'ard the ight.

O)r eyes and those of the pig dont have a tapet)m so theyO)r eyes and those of the pig dont have a tapet)m so theydont refe&t the ight.dont refe&t the ight.

This refe&ting of ight is a night vision adaptation be&a)seThis refe&ting of ight is a night vision adaptation be&a)seof stim)ation of the ight sensitive re&eptors in the retina.of stim)ation of the ight sensitive re&eptors in the retina.

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%$ Te ciliar& bod&%$ Te ciliar& bod&:: to'ard the imb)s the &horoidsto'ard the imb)s the &horoids

thi&6ness to form it.thi&6ness to form it.

'$ Te Iris:'$ Te Iris: the smaest part of thethe smaest part of thevas&)ar t)ni&( 'hi&h e!tends fromvas&)ar t)ni&( 'hi&h e!tends from

the &ornea to the ens.the &ornea to the ens.

It atta&hed to s&era and &iiaryIt atta&hed to s&era and &iiary

body by pe&tinate igament.body by pe&tinate igament. the opening in the &enter is thethe opening in the &enter is the

pulpipulpi

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The iris divided the spa&e bet'een theThe iris divided the spa&e bet'een theens and &ornea into anterior andens and &ornea into anterior andposterior &hambers tat &omm)ni&ateposterior &hambers tat &omm)ni&atethro)gh p)pi and fied 'ith( a,)eo)sthro)gh p)pi and fied 'ith( a,)eo)s

h)mor 8a &ear 'atery f)id9.h)mor 8a &ear 'atery f)id9.

The &oor of the iris determines the &oorThe &oor of the iris determines the &oorof the eyeof the eye

depends on the n)mber of thedepends on the n)mber of the

pigmented &es present in itspigmented &es present in itsstromastroma

the type of the pigment in the &es.the type of the pigment in the &es.

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Te internal tunic

The interna t)ni& of the eyeba &ontainsThe interna t)ni& of the eyeba &ontains

the ight/sensitive re&eptor &es 86no'n asthe ight/sensitive re&eptor &es 86no'n as

retina9.retina9. Its an e!tension of the brain to 'hi&hIts an e!tension of the brain to 'hi&h

remains &onne&ted by the opti& nerve.remains &onne&ted by the opti& nerve.

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Te internal tunic

The ayers in retina are:The ayers in retina are: singe ayer of pigmented &es. singe ayer of pigmented &es.

ne)roepitheiam ayer &ontaining the re&eptorne)roepitheiam ayer &ontaining the re&eptor&es( rods and &ones and their n)&ei.&es( rods and &ones and their n)&ei.

the rods for ba&6 and 'hitthe rods for ba&6 and 'hit

the &ones for the &oor vision.the &ones for the &oor vision. ayer of bipoar gangion &es. ayer of bipoar gangion &es.

ayer of m)tipoar gangion &es nonmyeinated ayer of m)tipoar gangion &es nonmyeinateda!ons ying interna to the &es and pass to thea!ons ying interna to the &es and pass to theopti& dis& 'here they form the opti& nerve.opti& dis& 'here they form the opti& nerve.

The opti& dis& is a bind area be&a)se there is noThe opti& dis& is a bind area be&a)se there is nore&eptor &ere&eptor &e..

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The adne!a of the eye

#.#. Te orbital fasciaeTe orbital fasciae::

a.a. Te periorbital:Te periorbital:is atta&hed nearis atta&hed nearthe opti& foramen at the ape! of thethe opti& foramen at the ape! of the&one .&one .

b.b. Te superficial muscular fascia:Te superficial muscular fascia:

ies 'ithin the periorbita. Its ooseies 'ithin the periorbita. Its ooseand fatty. nd enveops in theand fatty. nd enveops in theevator papebrae s)perioris and theevator papebrae s)perioris and thea&rima gand.a&rima gand.

&.&. Te deep muscular fascia:Te deep muscular fascia: isismore fibro)s and arises from themore fibro)s and arises from theeyeids and from the imb)s of theeyeids and from the imb)s of theeyeba.eyeba.

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The adne!a of the eye

2.2. Te muscles of te e&eball:Te muscles of te e&eball: The re&t)s m)s&es: dorsa(The re&t)s m)s&es: dorsa(

ventra( media and ateraventra( media and atera

are inserted anterior to theare inserted anterior to the

e,)ator by 'ide b)t verye,)ator by 'ide b)t verythin tendons.thin tendons.

The ventra and dorsaThe ventra and dorsa

obi,)e m)s&es: atta&h toobi,)e m)s&es: atta&h to

the eyeba near the e,)ator.the eyeba near the e,)ator.

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The adne!a of the eye2.2. Te muscles of te e&eball:Te muscles of te e&eball:

Te retractor bulbi arises fromTe retractor bulbi arises fromte vicinit& of te e&eball andte vicinit& of te e&eball andinserted on te e&eball posteriorinserted on te e&eball posteriorto te equator.to te equator.

Te levator palpebrae superioris:Te levator palpebrae superioris:striated muscle (itin te orbitstriated muscle (itin te orbittat doesn)t attac to te e&eballtat doesn)t attac to te e&eballbut passes over it to enter andbut passes over it to enter and

elevate te upper e&elidelevate te upper e&elid

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The adne!a of the eye".". Te e&elids and con*unctivaTe e&elids and con*unctiva::

The eyeids 8papebrae9 are t'oThe eyeids 8papebrae9 are t'om)s&)ofibro)s fods of 'hi&h them)s&)ofibro)s fods of 'hi&h the

)pper is the more e!tensive and)pper is the more e!tensive and

more mobie.more mobie.

The free margins of the ids areThe free margins of the ids are

meet at the media and atera angesmeet at the media and atera anges

of the eye and bo)nd an openingof the eye and bo)nd an opening

6no'n as the papebra fiss)re.6no'n as the papebra fiss)re.

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The adne!a of the eye'. Te e&elids and con*unctiva'. Te e&elids and con*unctiva ::

They are &onsist of three ayers:They are &onsist of three ayers:

1.The s6in: is thin and dei&ate and is1.The s6in: is thin and dei&ate and is&overed 'ith short hairs: it may aso&overed 'ith short hairs: it may aso&arry a fe' prominent ta&tie airs.&arry a fe' prominent ta&tie airs.

2.The m)s&)ofibro)s ayer: is formed by2.The m)s&)ofibro)s ayer: is formed bythe orbi&)aris o&)i( the orbita sept)m(the orbi&)aris o&)i( the orbita sept)m(the apone)rosis of the evator m)s&ethe apone)rosis of the evator m)s&eand the smooth tarsa m)s&e.and the smooth tarsa m)s&e.

".The m)&o)s 8papebra &on;)n&tiva9 a".The m)&o)s 8papebra &on;)n&tiva9 athin( transparent m)&o)s membranethin( transparent m)&o)s membrane

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The adne!a of the eye'. Te e&elids and con*unctiva'. Te e&elids and con*unctiva::

The third eyeid is s)pportedThe third eyeid is s)pportedby a T/shaped pie&e ofby a T/shaped pie&e of

&artiage.&artiage.

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The adne!a of the eye+.+. Te lacrimal apparatus:Te lacrimal apparatus:

Tis consists of lacrimal ,land properTis consists of lacrimal ,land proper

Te lacrimal ,land is flat and liesTe lacrimal ,land is flat and liesbet(een te e&eball and tebet(een te e&eball and tedorsolateral (all of orbit.dorsolateral (all of orbit.

Te ,lands associated (it te tirdTe ,lands associated (it te tirde&elidse&elids

several small accessor& ,landsseveral small accessor& ,lands- duct s&stem tat conve&s te lacrimalduct s&stem tat conve&s te lacrimal

fluid after it as (ased over te e&efluid after it as (ased over te e&einto te nasal cavit& for evaporation.into te nasal cavit& for evaporation.

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The bood s)ppy of the eye:

The arteries &an be divided into three gro)ps:The arteries &an be divided into three gro)ps:1.1. T#O%E %U$$=> E>E E>E OCU=R ?U%C=E%%U$$=> OCU=R ?U%C=E%

".". T#O%E =E@INA T#E OR DBCENTT#O%E =E@INA T#E OR DBCENT

%TRCTURE%.%TRCTURE%.

The e!terna ophthami& artery &arries the prin&ipe s)ppy ofThe e!terna ophthami& artery &arries the prin&ipe s)ppy of

the bood to the eye( 'hi&h is a bran&h of the ma!iary artery.the bood to the eye( 'hi&h is a bran&h of the ma!iary artery.

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The bood s)ppy of the eye: 19 The bran&hes of the e!terna19 The bran&hes of the e!terna

ophthami& for the eyeba penetrateophthami& for the eyeba penetratethe s&era to rea&h the vas&)arthe s&era to rea&h the vas&)art)ni& and retina.t)ni& and retina.

-ort posterior ciliar& a. -ort posterior ciliar& a. s)ppys)ppythe ad;a&ent &horoids in addition tothe ad;a&ent &horoids in addition to

bran&hes to the opti& nerve.bran&hes to the opti& nerve. ///on, posterior/on, posteriorciliar& a. ciliar& a. passpass

&ose the s&era &oser to the&ose the s&era &oser to thee,)ator.e,)ator.

-Te anterior ciliar& a. -Te anterior ciliar& a. s)ppys)ppy

the anterior potion of the &horoids(the anterior potion of the &horoids(the &iiary body and the iristhe &iiary body and the iris

These arteries anastomose to formThese arteries anastomose to formte ,reater arterial circle of tete ,reater arterial circle of te

iris.iris.

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29 The arteries that s)ppy the o&)ar m)s&es.29 The arteries that s)ppy the o&)ar m)s&es.

hi&h the absen&e of the arge vesses inhi&h the absen&e of the arge vesses in

dista ends red)&es beeding 'hen thedista ends red)&es beeding 'hen them)s&es are &)t d)ring the en)&eating.m)s&es are &)t d)ring the en)&eating.

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"9 The arteries that eave the orbit:"9 The arteries that eave the orbit:

-Te lacrimal a. -Te lacrimal a. s)ppy the a&rima gand in ro)te.s)ppy the a&rima gand in ro)te.

//Te supraorbital a. Te supraorbital a. send bran&hes to the )ppersend bran&hes to the )ppereyeidseyeids

-Te malar a. -Te malar a. s)ppy the eyeids and aso ad;a&ents)ppy the eyeids and aso ad;a&ent

area of the fa&e.area of the fa&e. -Te external etamoid a. -Te external etamoid a. s)ppy the ethamoids)ppy the ethamoid

abyrinth of the nasa &avity.abyrinth of the nasa &avity.

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The nerve s)ppy of the eye:

Te optic nerve II:Te optic nerve II:enters the orbit thro)ghenters the orbit thro)gh

the opti& foramen and passes to the ightthe opti& foramen and passes to the ight

re&eptor &es in the retina.re&eptor &es in the retina.

It ao's the movements of the eye and isIt ao's the movements of the eye and is

&overed by meninges that it a&,)ired d)ring its&overed by meninges that it a&,)ired d)ring its

deveopment.deveopment.

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Te Oculomoter nerve III:Te Oculomoter nerve III: &ontro the movement of the&ontro the movement of theeyeba. it enters the orbit thro)gh the orbita fiss)re.eyeba. it enters the orbit thro)gh the orbita fiss)re.

uppl&: dorsal" medial" ventral 0ectus muscleuppl&: dorsal" medial" ventral 0ectus muscle 1entral oblique muscle1entral oblique muscle Part of retractor musclePart of retractor muscle

Te abducent nerve 1I:Te abducent nerve 1I: enters thro)gh the orbitaenters thro)gh the orbitaforamen and innervates most of retra&tor b)bi and ateraforamen and innervates most of retra&tor b)bi and aterare&t)s m)s&es.re&t)s m)s&es.

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Te troclear nerve I1:Te troclear nerve I1: innervateinnervate Dorsa obi,)e m)s&eDorsa obi,)e m)s&e

Te tri,eminal nerve 1:Te tri,eminal nerve 1: send bran&hes to the eye.send bran&hes to the eye. Opthami& divisionOpthami& division

Aive sensory bran&hes to:Aive sensory bran&hes to:

1/ ong &iiary nerve of the eye( a&rima and s)praorbita nerves.1/ ong &iiary nerve of the eye( a&rima and s)praorbita nerves.

?a!iary division?a!iary division ygomati& bran&h s)ppy ventroatera segment of the eyeidsygomati& bran&h s)ppy ventroatera segment of the eyeids

and &on;)n&tivaand &on;)n&tiva

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Te facial nerve 1II:Te facial nerve 1II:

passes bet'een the eye and the ear givespasses bet'een the eye and the ear gives

a)ri&)opapebra bran&ha)ri&)opapebra bran&h

innervates the orbi&)aris o&)iinnervates the orbi&)aris o&)i

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