Category: Eye

Eye – a description of the body

Eye (глаз) – an organ of perception of light stimulation in some invertebrates (in particular, cephalopods), all vertebrates and humans. Most invertebrates function of the eye are less complex organs of vision, such as compound eyes. In vertebrates, the eye pair, are located in their sockets of the skull – and orbits consist of your own eyes or eyeballs, connected through the optic nerve to the brain, eyes and paranasal parts: age (see. the lids), lacrimal apparatus and eye-motor muscles. All vertebrates have a common type of eye structure.

The structure of the eye

Eye - a description of the bodyThe eyeball has a spherical shape. The central point of the front surface of the eye called the anterior pole, a point located on the rear surface, in the place of origin of the optic nerve – the posterior pole. The line connecting the poles of the eye is taken for an anatomical axis, it coincides with the geometrical axis. In the front, facing the light of the eye is located diopter (light-refracting) apparatus (refractive media system, which includes the cornea (See. The cornea), a transparent lenticular lens – the lens, aqueous humor and filling the cavity of the eye vitreous, as well as serving to accommodate the ciliary body and iris, or the iris), transmitting the image on a photosensitive retina (See. Retin-A), or retina.

The wall of the back of the eyeball consists of three shells, tightly adjacent to each other. The dense outer shell – the sclera – has a supporting and protective value; it gives the eye shape being like a skeleton. At the open front side of the eye, the sclera becomes thin and transparent cornea. Under the sclera is richly endowed with blood vessels choroid, the front of which is in the form of a thin plate forms the iris, which has a hole in the middle – the pupil. In the tissue of the iris in most vertebrates are special muscles – sphincter and dilator that, expanding and narrowing the pupil to regulate entry into the eyes of the light rays, and the iris, ie. A., Plays the role of the diaphragm.

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