Coats of the eyeballCoats of the eyeball Outer fibrous coatOuter fibrous coat : :

1-1-.cornea.cornea – anterior – anterior transparent part transparent part

2-2-sclerasclera---- posterior dense white -- posterior dense white part part

Middle vascular coatMiddle vascular coat : : 1- choroid (posteriorly)1- choroid (posteriorly)–– black vascular membrane black vascular membrane deep to deep to sclera.sclera. 2-ciliary body 2-ciliary body (middle),(middle),contains the contains the ciliary ciliary muscle (accomodation).muscle (accomodation). 3-Iris (anteriorly3-Iris (anteriorly) –) – it has it has opening in its center called the opening in its center called the pupilpupil + contains circular muscle + contains circular muscle fibres called fibres called sphincter pupillaesphincter pupillae + + radial muscle fibres called radial muscle fibres called dilator dilator pupillae.pupillae.

Inner nervous coatInner nervous coat : : the retinathe retina

The The ConjunctivaConjunctivaIt is a thin mucous

membrane that lines the inner surface of eyelids and reflected superiorly & inferiorly onto anterior surface of eyeball to form superior & inferior fornices.

Its epithelium is continuous with that of cornea.

The upper lateral part of superior fornix is pierced by ducts of lacrimal gland.

Levator palpebrae Levator palpebrae superiorissuperioris

Origin: roof of orbit above optic canal ,

Insertion: 1-by superior lamella (striated muscle) ---anterior surface of sup. tarsal plate +skin of upper lid. 2-by inferior lamella (smooth m.F).... Upper margin of sup.tarsal plate.

Nerve : 1-striated ms. by oculomotor N. 2-smooth ms. by superior cervical sympathetic F.

Action: elevation of upper eyelid.

Lesion of occulomotor or cervical symp.trunk leads to dropping of upper lid (Ptosis).

Sagittal section of eyeball

Tarsal plates: Dense fibrous tissue, lying in the eyelids and containing tarsal glands.

The eyelidsThe eyelids The aponeurosis of The aponeurosis of

insertion of levator insertion of levator palpebraepalpebrae superiorissuperioris pierces the pierces the orbital orbital septumseptum to reach to reach superior tarsal plate & superior tarsal plate & skin of upper eyelid.skin of upper eyelid.

The superficial surface The superficial surface of tof tarsal platesarsal plates + + orbital septumorbital septum are are covered by covered by palpebral palpebral part of orbicularis part of orbicularis oculi muscle.oculi muscle.

ActionAction : : 1-closed 1-closed by by orbicularis oculi. orbicularis oculi. 2-opened2-opened by levator by levator P.S.P.S.

The lacrimal The lacrimal apparatusapparatus Lacrimal gland :

1-main part (orbital part) lies in lacrimal fossa in anterolateral part of roof of orbit. 2-palpebral part lies in the lateral part of upper eyelid.

It gives 12 ducts : open into superior fornix of conjunctiva carrying tears to conj.sac.– lacrimal pucti - 2 canaliculi– lacrimal sac (lies in lacrimal groove behind medial palpebral ligament)– nasolacrimal duct– inferior meatus.

The Lacrimal The Lacrimal glandgland N.supply N.supply :: Parasymp.secretomotor fibers Parasymp.secretomotor fibers

via lacrimalvia lacrimal N.N. Preganglionic fibersPreganglionic fibers pass via pass via N. of N. of

pterygoid canalpterygoid canal to the to the pterygopalatine pterygopalatine ganglion.ganglion.

Postganglionic fibersPostganglionic fibers leave ganglion via leave ganglion via lacrimal N.lacrimal N. into into lacrimal gland.lacrimal gland.

N.of pterygoid canal

Fascial sheath of the Fascial sheath of the eyeballeyeball

It surrounds the eyeball It surrounds the eyeball posteriorly from the posteriorly from the optic optic nervenerve to the to the corneoscleral corneoscleral junction.junction.

It separatesIt separates the the eyeball eyeball from from the the orbital fatorbital fat and and provides provides the eyeballthe eyeball with with a socket for a socket for free movement.free movement.

Posteriorly,Posteriorly, it fuses with the it fuses with the dural sheath dural sheath of the of the optic optic nerve.nerve.

It is pierced by :It is pierced by : 1- 1-ciliary nerves & ciliary nerves & vessels. vessels. 2-2-tendons tendons of orbital musclesof orbital muscles , fascial , fascial sheath is reflected onto each sheath is reflected onto each ms. ms. as a tubular sheaths.as a tubular sheaths.

The fascial sheathsThe fascial sheaths for the for the tendons of the tendons of the

medial & lateralmedial & lateral recti recti are attached to the are attached to the med.& lat. walls of the orbit by med.& lat. walls of the orbit by medial &medial & lateral check ligaments.lateral check ligaments.

The lower part of fascial sheathThe lower part of fascial sheath below the below the eyeball is eyeball is thickenedthickened to form to form suspensory suspensory ligament of eye,ligament of eye, and and connects the check connects the check ligaments,ligaments, so it serves to suspend the so it serves to suspend the eyeball.eyeball.

The check & suspensoryThe check & suspensory ligaments of the eyeball.ligaments of the eyeball.

The OrbitThe Orbit

What is the What is the common tendinous ring ?common tendinous ring ? What are What are the structuresthe structures passing through passing through

the the openingsopenings in the orbit ? in the orbit ? Muscles of the orbit :Muscles of the orbit :

1-muscles of eyelids1-muscles of eyelids (levator (levator palpebrae superioris). palpebrae superioris). 2-extrinsic muscles of eyeball.2-extrinsic muscles of eyeball.

3-intrinsic muscles of eyeball3-intrinsic muscles of eyeball

The Common The Common tendinous ringtendinous ring

It is a fibrous ring of thickening of the periosteum.

It surrounds the optic canal and bridges the superior orbital fissure.

It gives origin to the 4 recti muscles.

The sup.R .arises from the upper part of the ring , The inf. R. arises from the lower part of the ring , The med.R. arises from the med.part of the ring. The lat.R. arises by 2-heads from the lateral part of the ring.

What are the structures What are the structures passing through the passing through the

openings in the orbit ?openings in the orbit ?

Maxillary N.+ inf. ophthalmic V..

The 4-Recti The 4-Recti musclesmuscles Origin:Origin: common tendinous ring. common tendinous ring.

Insertion:Insertion: they form they form a muscular a muscular conecone that encloses the optic nervethat encloses the optic nerve and post.part of eyeballand post.part of eyeball,/ ,/ each each tendon tendon of the muscles of the muscles pierces the pierces the fascial sheath of the eyeballfascial sheath of the eyeball and and inserted inserted into sclera,into sclera, 6 mm behind 6 mm behind margin of cornea margin of cornea (posterior to (posterior to corneoscleral junction)corneoscleral junction)

N.supply:N.supply: sup.,inf.,& medial recti sup.,inf.,& medial recti --- --- oculomotor N.oculomotor N./ lateral rectus--- / lateral rectus--- abducent N.abducent N.

Action:Action: each ms.directs the each ms.directs the cornea cornea 1-Superior R.---1-Superior R.--- upward & medially. upward & medially. 2-Inferior R.---2-Inferior R.--- downward & medially. downward & medially.

3-Medial R.–3-Medial R.– directs cornea directs cornea medially medially 4-lateral R.---4-lateral R.---laterally. laterally.

The 2 oblique The 2 oblique MusclesMuscles

Superior O.:Superior O.: originorigin– – post.wall post.wall of orbital cavityof orbital cavity (body of (body of sphenoid). sphenoid). InsertionInsertion---- its -- its tendon passes through trochlea tendon passes through trochlea (it is a(it is a fibro-cartilagenous fibro-cartilagenous pully attached to frontal pully attached to frontal bone),bone), then inserted then inserted into sup. into sup. surface of eyeball (sclera) surface of eyeball (sclera) beneath sup.rectus.beneath sup.rectus. N.supplyN.supply---- trochlear N. -- trochlear N. ActionAction– rotates – rotates eyeball,so that cornea looks eyeball,so that cornea looks downward and laterally.downward and laterally.

Inferior O.:Inferior O.: originorigin– – floor of orbital floor of orbital cavity. cavity. InsertionInsertion– – lateral surface of lateral surface of eyeballeyeball (sclera) ,deep to lateral (sclera) ,deep to lateral rectusrectus.. N.supplyN.supply---- -- N.to N.to inferior obliqueinferior oblique from from oculomotor oculomotor N.N.

ActionAction---- rotates eyeball so that -- rotates eyeball so that cornea looks cornea looks upwards & laterally.upwards & laterally.

Intrinsic muscles of eyeball Intrinsic muscles of eyeball (smooth muscles): (smooth muscles):Smooth ,involuntary muscles of

circular F (sphincter pupillae) & radiating F. (dilator pupillae).... lying in the iris.

Sphincter Pupillae N.supply : by parasymp.F. from oculomotor N. via N.to inferior oblique after relay in ciliary ganglion, postganglionic fibres pass to eyeball via short ciliary nerves. Action : constricts pupil in bright light & during accommodation.

Dilator Pupillae : N.supply : by symp.F, which pass to eyeball via long ciliary Ns. Action : dilates pupil in low intensity light & in excessive symp. activity as in fright.

Ciliary muscleCiliary muscle– smooth muscle in the ciliary body. N.supply– parasymp.F. of 3rd N. as sphincter pupillae muscle. Action : accomodation by making lens more biconvex and increasing the refractive power of lens.

The EndThe End

Sensory Nerves :Sensory Nerves : 1-optic 2-(lacrimal)1-optic 2-(lacrimal) 3-frontal. 4-(nasociliary)3-frontal. 4-(nasociliary)

Optic Nerve :Optic Nerve : It is the It is the sensory nerve of vision.sensory nerve of vision.

Arise from the retina,and Arise from the retina,and peirces the posterior surface peirces the posterior surface of sclera. of sclera.

It passes through the It passes through the optic optic canal ,canal ,accompanied by theaccompanied by the ophthalmic arteryophthalmic artery (below & (below & lateral to N.)lateral to N.) into the middle into the middle cranial fossa, where it joins cranial fossa, where it joins the optic chiasma.the optic chiasma.

It is surrounded by It is surrounded by ciliary ciliary nervesnerves & vessels& vessels and and 4 4 recti muscles.recti muscles. It is It is surrounded also by surrounded also by meninges,meninges, which fuse with which fuse with the posterior part of sclera. the posterior part of sclera.

Lacrimal N :Lacrimal N :++parasymp.parasymp.It arises from

ophthalmic division of trigeminal N. in lateral wall of cavernous sinus.

It enters orbit through S.O.F, outside tendinous ring.

It passes forward above lateral rectus muscle to enter lacrimal gland (parasymp.secretomotor N.).

It ends by supplying skin of lateral part of upper lid.

Frontal N. :As above in orgin and enters orbit through S.O.F, outside tendinous ring.

It passes forward above L.P.S muscle and ends by dividing into supraorbital & supratrochlear nerves to supply skin of forehead.

Nasociliary Nasociliary NerveNerve

Origin : from ophthalmic N. of trigeminal N. in the lateral wall of cavernous sinus.

It enters orbit through sup. Orbital fissure inside the tendinous ring.

It passes medially, crossing above optic N. with ophthalmic artery to reach medial wall of orbit., along upper margin of medial rectus to end by dividing into 2 terminal branches.

Branches : 1-sensory root to ciliary ganglion : to supply eyeball through short ciliary Ns. 2-2 long ciliary Ns. : contains sympathetic Fs. To dilator pupillae. 3-posterior ethmoidal N. : to supply ethmoid air sinuses. 4-anterior ethmoidal N. : one of the terminal branches. 5- infratrochlear N. : its 2nd terminal branch.

Motor nerves:Motor nerves: 1-Oculomotor 1-Oculomotor 2-Trochlear 2-Trochlear 3-Abducent3-Abducent Oculomotor N.:Oculomotor N.:

Sup.divisionSup.division leaves lat.wall leaves lat.wall of cavernus sinus and of cavernus sinus and enters the orbit through enters the orbit through sup.orbital fissure,sup.orbital fissure,insideinside tendinous ring.It supplies tendinous ring.It supplies sup.rectussup.rectus & & levator P.S.levator P.S.

Inf.divisionInf.division--- as --- as above ,and supplies above ,and supplies inf.rectus inf.rectus ,,med.rectus med.rectus ,and ,and inf.oblique.inf.oblique. The nerve toThe nerve to inf.obliqueinf.oblique gives off gives off preganglionic Fs. to preganglionic Fs. to ciliary ciliary ganglion ganglion and carries and carries parasympathetic fibersparasympathetic fibers to to the the sphincter pupillaesphincter pupillae & & ciliary muscles, via short ciliary muscles, via short ciliary nervesciliary nerves

Trochlear & abducent Trochlear & abducent nervesnerves

Trochlear N. leaves lat.wall of cavernus S. To enter orbit through S.O.F, outside tendinous ring ---- to supply sup.oblique muscle.(SO4).

Abducent N. leaves cavernus sinus to enter orbit through S.O.F, within tendinous ring---- to supply lateral rectus (LR6)

The ciliary ganglionThe ciliary ganglionIt is parasympathetic ganglion, situated in the posterior part of the orbit lateral to optic nerve.

It receives preganglionic parasymp.f. from nerve to inf.oblique of oculomotor N.

It sends postganglionic Fs. via short ciliary nerves to the eyeball to supply--- sphincter pupillae & ciliary muscle.

Few sympathetic Fs. pass from internal carotid plexus into orbit without relay in the ganglion.

Ophthalmic arteryOphthalmic arteryIt is a branch of the int.carotid artery after it emerges from the cavernous sinus.

It passes through the optic canal below & lateral to the optic nerve, then crosses above it to reach medial wall of orbit. It is now gives off numerous branches.

Branches : ….

Branches of Branches of Ophthalmic arteryOphthalmic arteryCenteral artery of

retina : it pierces meningeal sheaths of optic N. to enter inside substance of optic N. to reach eyeball (optic disc) and divides into terminal end arteries.

Muscular branches.

Ciliary arteries : anterior group which enter eye at corneoscleral junction & posterior group, which enters near optic N.

Lacrimal artery : to lac.gland.

Supratrochlear & supraorbital arteries to skin of forehead.

Ophthalmic veinsOphthalmic veins Sup.oph.VSup.oph.V.communicates in front with the .communicates in front with the

facial V.facial V. Inf.oph.VInf.oph.V.communicates .communicates throuth the inf.orbital throuth the inf.orbital

fissurefissure with the with the pterygoid venous plexus.pterygoid venous plexus. Both veins passBoth veins pass backward throughbackward through sup.orbital fissuresup.orbital fissure to drain into the to drain into the cavernous sinus.cavernous sinus. No lymph vessels No lymph vessels

or nodes or nodes are present are present in orbital cavity. in orbital cavity.

Medial rectus.

Lateral rectus.

Superior rectus.

Inferior rectus.

Superior oblique.

Inferior oblique.

The optic discThe optic disc

It is the site where the It is the site where the optic N. leaves optic N. leaves the retinathe retina. .

It is the site where it is It is the site where it is pierced by the pierced by the centeralcenteral artery of the retinaartery of the retina ,and there ,and there is complete is complete absence of rods & conesabsence of rods & cones, , so that it is so that it is insensitive to lightinsensitive to light and is and is referred to as * referred to as * Blind SpotBlind Spot. .