ORGAN OF SIGHT. STRUCTURE OF EYEBALL TUNICS. THE REFRACTORY MEDIA OF EYEBALL

Eye consists of eyeball, auxiliary eye organs and the optic nerve. Eyeball has nucleus and wall. Auxiliary eye apparatus includes eyelids, muscles of eyeball, lacrimal apparatus, orbital fasciae, vessels and nerves.

Eyeball is serrounded by adiposal body of orbite, muscles of eyeball and orbital fascia. Bony orbit is covered by periorbita. It has an anterior pole, posterior pole, and axis. Axis courses between poles. Optic axis starts from anterior pole to central fossa of the retina. Line that is found transversal on surface of eyeball and is found in the middle to distance between poles is called equator, and line passing perpendicularly to equator is called meridian.

Eyeball wall consists of three coats: fibrous (external), vascular (middle) and internal (retina).

Fibrous coat of eyeball subdivides on transparent cornea (anteriorly) and sclera (the rast). Venous sinus of sclera (Schlemm`s canal) localised between cornea and sclera.

Internal coat of eyeball – ‘retina’. There are external pigmental layer and internal nervous layer in visual part of the retina. According to function they distinguish posterior larger visual part of retina, which contains rods and cones, and lesser blind part of retina. There are neither rods nor cones in blind part.

Ora serrata is the boundary between optic and blind parts, which accords with transition of choroid into ciliary body. In posterior part of retina is found a disc of the optic nerve that has a small concavity. Macula is located in the centre of retina. Central fossa is the place of best sight sharpness, where is observed most rods and cones.

Nucleus of eyeball consists of vitreous body, lens, and aqueous humor in anterior and posterior chambers.

Vitreous body represents by transparent mass without any vessels. It occupies largest portion of eyeball behind lens.

The transparent lens consists of tight layers of proteins. The thin, clear lens capsule encloses the lens and provides attachment for the suspensory ligament (zonular fibers).

Anterior chamber of eyeball placed between posterior surface of cornea surface and anterior surface of the iris. Posterior chamber is found between posterior surface by iris and anterior surface of lens. The anterior and posterior chambers are filled by aqueous humor, which produced by ciliary processes of ciliary body and unite each other by the medium of pupil. Between cornea and iris is found iridocorneal corner, which is filled by pectinate ligament with the Fontana`s spaces. Aqueous humor draines from anterior chamber through fountain spaces to the Schlemm`s canal (venous sinus of sclera).Поділитися цим:

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AnnaR

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Коментарі: 0Публікації: 9Реєстрація: 09-02-2021

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