ORGAN OF VISION. 2ND CRANIAL NERVE

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.

Vascular eye coat has: 1] proper vascular coat ‘choroidea’, which connects with sclera and delimited by perivascular space. 2] Ciliary body consists of ciliary corona and by 70 ciliary processes. There is ciliary muscle in ciliary body, its contraction provides eye accommodation. 3] Iris carries the round oriface in centre – pupilla. Smooth muscles, which form a pupil muscle-sphincter and pupil muscle-dilator are round the pupil.

 

 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.Поділитися цим:

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