The eyes or body of view, consists of the eyeball and the optic nerve and subsidiary bodies (eyelids, lacrimal apparatus, muscles of the eyeball.
The eyeball is almost spherical education with a diameter of approximately 24 mm, located in an eye-socket. It has a high mobility in the result of the activities of the six eye muscles - four straight (top, bottom, inside and outside) and two slashes (top and bottom). The eyeball is separated from the rest of the holes of the dense fibrous sheath - tenon's capsule, behind which is fatty tissue.
The wall of the eyeball consists of three shells: outer - dense fibrous membrane consisting of the cornea and sclera; middle, vascular, and internal - retina (the retina). Inside the eyeball are the lens and vitreous body. Camera eyeball filled intraocular fluid, aqueous humor.
1 - sclera;
2 - vascular sheath;
3 - netted shell;
4 - the optic nerve;
5 - rear long ciliary artery;
6 - verticasa Vienna;
7 - bottom rectus;
8 - iris;
9 - cornea;
10 - conjunctiva;
11 - the lens;
12 - the ciliary body;
13 - top rectus.)
Sclera, consisting of a dense collagen fibers, opaque, poor blood vessels. The front of the sclera covered conjunctiva. On border of connection sclera with transparent cornea has a shallow groove width of about 1 mm, nazvy limb. Cornea is the transparent avascular education, optical acting like a strong convex glass. It has a very high sensitivity due to the large number of nerve endings located mainly in the surface layers of it.
Vascular shell eyes, or uveal tract consists of the iris, ciliary, or ciliary body and actually choroid - choroid. Iris, or iris,is the front part of the choroid. In the center of the iris has a round hole - the pupil, through which light rays penetrate inside the eyeball and the retina. Depending on the intensity of the light flux the pupil is able to change its value: in the bright light he has, in low and in the dark - wider. The size of the pupil changes as a result of interaction of smooth muscle fibers - sphincter or dilatatore, prisoners in the iris and innervated parasympathetic and sympathetic nerves. For a number of diseases occurs pupil dilation-midriaz, or narrowing - cramps (see Pupillary reflexes). Iris contains a different number of pigment, which determines its color (eye color). Behind the iris is the ciliary body, which includes the ciliary, or accommodative, muscle (see accommodation of the eye). On the inner surface of the ciliary body, in front of his thirds are ciliary processes. Thereto are attached fibre ciliated belt (Zinovy ligaments), which suspended the lens. Ciliary body produces intraocular liquid. Posterior to the ciliary body goes into actually vascular shell (choroid), which consists mainly of vessels of different caliber. Many rich pigment cells of the choroid prevent the penetration of light through the sclera, eliminating the scattering.
The internal layer of the eyeball - retina consists of high differentiation of neural elements. Microscopically there are 10 layers. The outer layer is svetovosprinimayuschie, he turned to the vascular coating and consists of neuroepithelial cells, rods and cones, perceiving light and color. The following layers are formed conducting nervous irritation cells and nerve fibers. Nerve fibers form the optic nerve. By region, the highest vision in the retina is the so nasypnoe yellow spot with a Central hole, containing only the cones.
Much refracts rays of light transparent elastic lens is shaped, biconvex lens. Vessels and nerves of the lens does not have. The absence of the lens in the eye [after cataract extraction (see) or resorption of the injured lens] is called aphakia.
The vitreous body, filling a large part of the cavity eyeball - transparent gelatinous weight consisting of a thin, delicate fibrils with up to 99% water. The vitreous body also refracts rays of light.
In the cavity eyeball small space, limited the rear surface of the cornea, the front surface of the iris and the Central part of the front surface of the lens, called the anterior chamber of the eye; she made a transparent liquid. The periphery of the anterior chamber of the eye, called the anterior chamber angle, is important in the circulation of an intraocular liquid. Space is restricted to the rear surface of the iris, the peripheral part of the lens and the internal surface of the ciliary body, called the rear of the camera; it also made watery moisture, which is the power source avascular tissues eye - Rogova shell, lens and vitreous body.
To the auxiliary device eyes but muscles are forever (see) and the tear bodies (see).
Conjunctiva - connection (mucosal) layer of the eye in the form of a thin transparent film covers the rear surface century and the front of the eyeball over the sclera to the cornea. When the eyelids open, conjunctiva is represented as the bag with a wide slit - eye slit. The inner corner of the eye is located lacrimal pulp. Conjunctiva not hinder the mobility of the eyeball, transparent, smooth; in the field of cartilage century through it Shine meibomiae cancer. With rich neurovascular apparatus, conjunctiva reacts to any irritation (conjunctival reflex).