ANATOMY OF THE EYE

ANATOMY OF THE EYEYudo PrabowoI11110017Embriologi Bola MataMulai berkembang pada minggu keempat pada proses embriogenesis. Forebrain retina dan saraf optic. Ectoderm lensa dan beberapa struktur aksesoris dari bagian anterior mata.Mesenchyme lapisan-lapisan mata dan berhubngan dengan struktur dari orbita. EXTERNAL ANATOMY OF THE EYE

Bony Orbit Cavity containing and protecting five sixths of eyeball, associated muscles, nerves, and vessels. Opening is protected by a thin moveable fold: the eyelid. Supports, protects and maximizes the functions of the eye Pyramidal shape with apex directed posteriorly and base anteriorly

Rongga Orbita berbentuk limas segiempat dengan puncak ke arah dalam.

4Boundaries :Roof Orbital plate frontal bone Lesser wing sphenoid Fossa for lacrimal gland found in orbital part Floor Orbital plate of maxilla Some contributions from zygomatic and palatine bones Contains inferior orbital fissure from apex to orbital margin Medial wall Paper thin Orbital plate of ethmoid bone Some contributions from frontal, lacrimal, and sphenoid bones Indented by lacrimal fossa for lacrimal sac Lateral wall Frontal process of zygomatic bone Greater wing of sphenoid Apex Lesser wing of sphenoid Contains optic canal medial to superior orbital fissure

Foramina of the orbital cavity

ForamenLocationStructures TransmittedSupraorbital grooveSupraorbital margin Supraorbital nerve and blood vesselsInfraorbital groove and canalOrbital plate of maxilla (floor)Infraorbital nerve and blood vesselsNasolacrimal canalMedial wallNasolacrimal ductInferior orbital fissureBetween greater wing sphenoid and maxillaMaxillary nerveZygomatic branch maxillary nerveOphthalmic veinSympathetic nervesSuperior orbital fissureBetween greater and lesser wings sphenoidLacrimal nerveFrontal nerveTrochlear nerveOculomotor nerveAbducent nerveNasociliary nerveSuperior ophthalmic veinOptic canalLesser wing sphenoidOptic nerveOphthalmic arteryZygomaticofacial foramenLateral wallZygomaticofacial nerveAnterior ethmoidal foramenEthmoid boneAnterior ethmoidal nervePosterior ethmoidal foramenEthmoid bonePosterior ethmoidal nerve

Eyelids and Lacrimal Apparatus

EyelidsThe eyelids protect the eyeballs and keep the corneas moist.Each eyelid contains a tarsal plate of dense connective tissue; tarsal glands that secrete an oily mixture into the tears; and a small slip of smooth muscle (superior tarsal [Mllers] muscle) in the superior eyelid. (The tears contain albumins, lacto ferrin, lysozyme, lipids, metabolites, and electrolytes.)

ConjunctivaMucous membrane with non keratinized squamous epithelium and goblet cellsThin, richy vascularized substantia propriaCan be divided into three geographic zones:PalpebralFornicealBulbar

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The lacrimal apparatus includes :Lacrimal glands: secrete tears; innervated by the facial nerve parasympatheticsLacrimal ducts: excretory ducts of the glandsLacrimal canaliculi: collect tears into openings on the lids called the puncta, and convey them to the lacrimal sacsLacrimal sacs: collect tears and release them into the nasolacrimal duct when one blinks (contraction of the orbicularis oculi muscle)Nasolacrimal ducts: convey tears from lacrimal sacs to the inferior meatus of the nasal cavity

Contents of the Orbit

EyeballSurrounded by fascial sheath (Tenon's capsule) From optic nerve to junction of cornea and sclera Forms socket Pierced by tendons of extraocular muscles Three layers Outer fibrous = sclera and cornea Middle vascular = choroid, ciliary body and iris Inner pigmented and nervous = retina

Fibrous coat Sclera = opaque part of fibrous coat Covers posterior five sixths of eyeball Visible through conjunctiva is the white of the eye Pierced posteriorly by optic nerve Cornea Transparent part of fibrous coat Transmits light The cornea is nourished with nutritive metabolites (amino acids and glucose) from three sources:Diffusion from the capillaries at its edge.Diffusion from the aqueous humor.Diffusion from the tear film.

Middle vascular layer Choroid Outer pigmented layer Inner vascular layer Lies between sclera and retina Lines most of sclera Terminates anteriorly as ciliary body Ciliary body Connects choroid with iris Contains smooth muscle that alters the shape of lens Folds on internal surface (ciliary processes) produce aqueous humor and attach to suspensory ligament of lens Iris Pigmented diaphragm with central aperture: the pupil Contains smooth muscle that alters the size of the pupil to regulate the amount of light entering the eye Radial fibers of the dilator pupillae open the pupil Circular fibers of the sphincter pupillae close the pupil

Inner (retinal) layer Consists of three parts Optic part (1) Receives light Composed of two layers: inner neural layer and outer pigmented layer Inner neural layer contains photosensitive cells: rods for black and white and cones for color Ciliary and iridial parts (2 and 3) Continuation of pigmented layer plus a layer of supportive cells Cover ciliary body and posterior surface of retina Fundus Is posterior part of eye Contains optic disc = depressed area where optic nerve leaves and central artery of the retina enters Optic disc contains no photoreceptors = "blind spot" Macula lutea Small oval area of retina Contains concentration of photoreceptive cones for sharpness of vision Depression in center = fovea centralis, area of most acute vision

Neural retina ends anteriorly at ora serrata Serrated border posterior to ciliary body Termination of light receptive part of retina Vasculature of retina Central artery of retina from ophthalmic artery Retinal veins drain to central vein of retina Rods and cones receive nutrients directly from vessels in the choroid Chambers of the eye Anterior chamber Between cornea anteriorly and iris/pupil posteriorly Contains aqueous humor Posterior chamber Between iris pupil anteriorly and lens and ciliary body posteriorly Contains aqueous humor Vitreous chamber/Body Between lens and ciliary body anteriorly and retina posteriorly Contains vitreous body and vitreous humor

Light refraction Cornea Refracts light that enters eye Transparent and sensitive to touch (ophthalmic nerve = CN V1) Aqueous humor in anterior chamber Refracts light Provides nutrients for cornea Produced by ciliary body Circulates through Canal of Schlemm in iridocorneal angle Lens Transparent, enclosed in capsule Shape changed by ciliary muscles via suspensory ligaments attached around periphery Convexity varies to adjust for focus on near or far objects Parasympathetic stimulation of ciliary muscle reduces tension of suspensory ligaments and lens rounds up for near vision Absence of parasympathetic stimulation relaxes ciliary muscle, increases tension on suspensory ligaments and flattens lens for far vision

Muscles of the Orbit Intrinsic (intraocular) muscles Ciliary muscle Constrictor pupillae of iris Dilator pupillae of iris Extrinsic (extraocular) muscles Six muscles Four arise from common tendineus ring surrounding optic canal and part of superior orbital fissure Lateral and medial rectus (2) Lie in same horizontal plane Rotate eyeball laterally and medially, respectively Superior and inferior rectus (2) Lie in same vertical plane Pull eyeball superiorly and inferiorly, respectively

Inferior oblique Works with superior rectus Pulls eyeball superiorly and laterally Superior oblique Works with inferior rectus Pulls eyeball inferiorly and laterally Sheathed by reflection of fascial sheath around eyeball (Tenon's capsule) Medial and lateral check ligaments Triangular expansions of sheath of medial and lateral rectus muscles Attached to lacrimal and zygomatic bones Limit abduction and adduction Suspensory ligament Union of check ligaments with fascia of inferior rectus and inferior oblique muscles Forms sling that supports eyeball

Muscle

OriginInsertionActionNerve SupplyBlood SupplyExtrinsic muscles of the eyeballSuperior rectusCommon tendinous ringSuperior aspect of eyeball, posterior to the corneoscleral junctionElevates, adducts, and medially rotates eyeballOculomotor nerve (CN III) -superior divisionOphthalmic arteryInferior rectusCommon tendinous ringInferior aspect of eyeball, posterior to corneoscleral junctionDepresses, adducts, and laterally rotates eyeballOculomotor nerve (CN III) -superior divisionOphthalmic arteryMedial rectusCommon tendinous ringMedial aspect of eyeball, posterior to corneoscleral junctionAdducts eyeballOculomotor nerve (CN III) -superior divisionOphthalmic arteryLateral rectusCommon tendinous ringLateral aspect of eyeball, posterior to corneoscleral junctionAbducts eyeballAbducent nerve (CN VI)Ophthalmic arterySuperior obliqueBody of sphenoid, above optic foramen and medial origin of superior rectusPasses through trochlea and attaches to superior sclera between superior and lateral rectiAbducts, depresses, and medially rotates eyeballTrochlear nerve (CN IV)Ophthalmic arteryInferior obliqueAnterior floor of orbit lateral to nasolacrimal canalLateral sclera deep to lateral rectusAbducts, elevates, and laterally rotates eyeballOculomotor nerve (CN III) -inferior divisionOphthalmic arteryMuscles of eyelidsLevator palpebrae superiorisLesser wing of sphenoid, anterior to optic canalSuperior tarsal plateRaises upper eyelidOculomotor nerve (CN III) -superior divisionOphthalmic arteryOrbicularis oculiMedial orbital margin, palpebral ligament, and lacrimal boneSkin around orbit palpebral ligament, upper and lower eyelidsCloses eyelidsFacial nerve (CN VII)Facial and superficial temporal arteriesIntrinsic muscles of the eyeSphincter pupillae (iris)Circular smooth muscle of the iris that passes around pupilConstricts pupilParasympathetic fibers via occulomotor (CN III)Ophthalmic arteryDilator pupillae (iris)Ciliary bodyDilates pupilSympathetic fibers via long ciliary nerves (CN V1)Ophthalmic arteryCiliary musclesCorneoscleral junctionCiliary bodyControls lens shape (accommodation)Parasympathetic fibers via short ciliary nerves (CN V1)Ophthalmic arteryBlood Supply to the Orbit and EyeOphthalmic artery (main supply) Enters orbit through optic canal Lateral to optic nerve Infraorbital artery from maxillary Branches of ophthalmic artery Supraorbital Supratrochlear Lacrimal Dorsal nasal Ethmoidal-anterior and posterior Central artery of the retina Branch of ophthalmic Runs within dural sheath of optic nerve Emerges at optic disc and branches over retina Posterior ciliary arteries Branches of ophthalmic Six short to choroid Two long to ciliary plexus Anterior ciliary From muscular branches of ophthalmic Anastomoses with posterior ciliary arteries

Distribution of Branches of Ophthalmic Artery Branch (in order of origin)Structures SuppliedLacrimal arteryLacrimal gland, conjunctive and eyelidsShort posterior ciliary arteriesChoroid layer of retina to supply visual layerLong posterior ciliary arteryCiliary body and irisCentral artery of retinaRetinaSupraorbital arteryForehead and scalpPosterior ethmoidal arteryPosterior ethmoid air cellsAnterior ethmoidal arteryAnterior and middle ethmoid air cells, frontal sinus, nasal cavity, skin of noseDorsal nasalDorsum of noseSupratrochlearForehead and scalp

Innervation of the Orbit 34

Innervation of the Orbit Optic nerve Formed from axons of retinal ganglion cells Exits through optic canal Fibers from medial half of each retina cross at optic chiasm and join uncrossed fibers from lateral half of contralateral retina to form optic tract Oculomotor nerve (CN III) Runs in lateral wall of cavernous sinus Enters orbit through superior orbital fissure Contains parasympathetic fibers to sphincter pupillae and ciliary muscles Supplies Levator palpebrae superioris Superior rectus Medial rectus Inferior rectus Inferior oblique Trochlear nerve (CN IV) Runs in lateral wall of cavernous sinus Passes through superior orbital fissure Supplies superior oblique muscle

Abducent nerve (CN VI) Courses through cavernous sinus Enters orbit via superior orbital fissure Innervates lateral rectus muscle Branches of the ophthalmic nerve (CN V1) Lacrimal nerve to lacrimal gland Frontal nerve Divides into supraorbital and supratrochlear Supplies upper eyelid, forehead, and scalp Nasociliary nerve and its branches Infratrochlear to eyelids, conjunctiva, and nose Anterior and posterior ethmoidal nerves to sphenoid and ethmoid sinuses and anterior cranial fossa Long ciliary nerves to dilator pupillae Short ciliary nerves Branches from ciliary ganglion Carry parasympathetic and sympathetic fibers Innervate ciliary body and iris

FISIOLOGI MATAFungsi-fungsi Bagian MataKelopak mata penutup untuk melindungi bagian anterior mataKelenjar lakrimal menghasilkan air mata yang berfungsi sebagai pelumas, pembersih, dan bahan bakterisidalBulu mata menangkap kotoran halus di udara sebelum masuk ke mataMata terbagi menjadi 3 lapisanSkleraSklera jaringan ikat yang membentuk bagian putih mataKoroidlapisan yang berpigmen banyak dan mengandung banyak pembuluh darah untuk nutrisi retinaRetina lapisan berpigmen di sebelah luar dan lapisan jaringan saraf di sebelah dalam. Mengandung sel batang dan sel kerucut fotoreseptorKornea struktur refraktif mataLensa struktur refraktif mataHumor vitreus mempertahankan bentuk bola mataBadan siliar menghasilkan humor aquous yang berfungsi membawa nutrien untuk kornea dan lensaIris dan pupil berfungsi mengatur jumlah cahaya yang sampai ke retina

Proses RefraksiStruktur refraktif yang penting pada mata yaitu kornea dan lensaBerkas cahaya divergen dibelokkan (refraksi) agar dapat difokuskan ke titik fokus (retina) bayanganPermukaan refraktif mata berbentuk konveks membawa sinar ke titik fokus

Kornea berperan paling besar dalam kemampuan refraktif mataLensa memiliki daya akomodasi otot siliarisOtot siliaris relaksasi ligamentum suspensorium menegang lensa menggepang kemampuan refraktif untuk melihat jauhOtot siliaris kontraksi ligamentum suspensorium mengendur lensa membulat kemampuan refraktif untuk melihat dekatProses FototransduksiBerkas cahaya yang masuk difokuskan ke sel batang dan sel kerucut (fotoreseptor retina)Fotoreseptor dibagi menjadi 3 bagian:Segmen luar mendeteksi rangsangan cahayaSegmen dalam mengandung perangkat metabolikTerminal sinaps menyalurkan sinyal yang dihasilkan fotoreseptorSegmen luar fotoreseptor fotopigmen terkena sinar teraktivasi potensial aksi menyalurkan informasi ke otak pemrosesan visualTerdapat empat fotopigmen:Rodopsin sel batang, menyerap semua panjang gelombang cahaya tampak (400 700 nm) bayangan abu-abu dengan perbedaan intensitasSel kerucut merah, hijau, dan biru sel kerucut, berespon secara selektif terhadap berbagai panjang gelombang cahaya penglihatan warna

Fototransduksi proses pengubahan rangsangan cahaya menjadi sinyal listrikFotoreseptor mengalami hiperpolarisasi ketika menyerap cahaya

Aktivitas Fotoreseptor pada Keadaan GelapGelap konsentrasi cGMP saluran Na+ terbuka depolarisasi membran membuka saluran Ca2+ di ujung sinaps pelepasan neurotransmiter inhibitorik sel bipolar terhambat tidak timbul potensial aksi di sel ganglion tidak ada perambatan potensial aksi ke korteks penglihatanAktivitas Fotoreseptor pada Keadaan terangCahaya pengaktifan fotopigmen pengaktifan transdusin cGMP siklik penutupan saluran Na+ hiperpolarisasi membran menutup saluran Ca2+ di ujung sinaps pelepasan transmiter inhibitorik sel bipolar tidak terhambat (tereksitasi) perubahan potensial potensial aksi di ganglion perambatan potensial aksi ke korteks penglihatan