The main bodies
The main basic unit responsible for the reception, is the eyeball (bulbus oculi). It has an irregular spherical shape and is located in the anterior orbit. Most of the eyeball is hidden, and you can see only the cornea (cornea) and the adjacent small area. In the center of the front surface of the cornea is the anterior chamber of the eyeball (camera anterior bulbi). Rear camera (camera posterior bulbi) is located near the exit of the optic nerve, in the central part of the posterior segment of the eyeball.
The inner core of the eyeball, consisting of a lens (lens), the vitreous body (corpus vitreum) and aqueous humor (humor aquosus), surrounded by three membranes.
The outer shell, which is also known as fibrous or fibrous (tunica fibrosa bulbi), consists of dense fibrous connective tissue, whose properties provide shape retention of the eyeball. Anterior is called the cornea, has a concave-convex shape and is the outermost part of the eyeball. In the cornea contains a huge number of nerve endings, but completely absent lymphatic and blood vessels, which ensures transparency. Posterior part of outer membrane called the sclera (sclera) and is a continuation of the cornea. The sclera is opaque and does not transmit light. The front outer surface of the sclera is covered by mucous membranes - the conjunctiva (tunica conjunctiva). The back of the sclera and inner surface covered with endothelium. Go to the sclera attached muscles, blood vessels and nerves, including the optic nerve (n. opticus).
Average shell, called vascular (tunica vasculosa bulbi), contains blood vessels, pigment cells and consists of three divisions. The first of these is actually the choroid (chorioidea). It is located on the inner surface of the sclera and in the place where the sclera becomes the cornea smoothly into the ciliary body (corpus ciliare), which is the second part of the choroid.
Ciliary body consists of the ciliary muscle (m. ciliaris), the ciliary rim (corona ciliaris), ciliary circle (orbiculus ciliaris), ciliary body stroma, loose connective tissue, rich in pigmentation, and blood vessels. The front part of the choroid is the iris or the iris (iris). It is not adjacent to the outer shell is an extension of the ciliary body and shine through the cornea.
Space separating the iris from the cornea is the anterior chamber of the eyeball and is filled with clear liquid. The iris is composed of smooth muscle, loose connective tissue, blood vessels and nerve fibers. On its posterior surface are pigment cells that cause eye color. In the center of the iris is the pupil (pupilla), which transmits light into the eyeball. Thanks to the smooth muscle can contract the pupil (due to the circular muscle) or expanded (due to the radial muscles), depending on the amount of perceived light.
The inner shell of the eyeball called the retina (retina). Outer surface is adjacent to the choroid, and inner - to the vitreous body. Retina form a branched end of the optic nerve and several layers of cells. Nevroepitelialny layer (stratum neuroepitheliale) contains the light and color receptors: rods (bacilli), who perceive the brightness of light, and cones (coni), are able to distinguish colors.
Results of the retina contains about 130 million rods and 7 million cones. On the rear surface of the retina is the optic disc (discus n. optici), which departs from the trunk of the optic nerve. According to it, perceived receptors impulses come from the retina to the cortex of the occipital lobe of the cerebral hemispheres, where the cortical end of the visual analyzer.
Go to the optic nerve attached to the blood vessels. On the disc itself is a so-called blind spot - the area of ??the retina devoid of receptors. Prior to the optic disc is the best spot of vision (macula) - area of ??the retina that contains only cones.
Behind the iris is the lens that faces it more flat front surface and rear, more convex - a vitreous body. The lens is made of transparent fibers that do not contain blood vessels and nerves that make up the lens cortex (cortex lentis) and a dense core of the lens (nucleus lentis). It is surrounded by a capsule (capsula lentis), riddled with belt fibers (fibrae zonulares), by which the lens is attached to the ciliary body, more precisely, to the ciliary muscle, which regulates the curvature of the lens. Behind the iris is located posterior chamber of the eyeball filled with aqueous humor, which is produced by the vessels of the iris and ciliary body.
For the lens is the vitreous, which is closely adjacent to the retina, the anterior surface of the lens make it easier, and fills most of the cavity of the eyeball. Vitreous consists of transparent gelatinous mass, which is rich proteins glassy moisture (humor vitreus) and fine fibrils. Vessels and nerves in it does not contain. Vitreous body is surrounded by the glassy membrane (membrana vitrea).
|In Fig. 283.
Diagram of the eyeball elevation
1 - the cornea;
2 - the anterior chamber of the eyeball;
3 - iris;
4 - posterior chamber of the eyeball;
5 - lens;
6 - ciliary muscle;
7 - the conjunctiva;
8 - ciliary body;
9 - the lateral rectus of the eyeball;
10 - medial rectus of the eyeball;
11 - actually the choroid;
12 - vitreous body;
13 - the sclera;
14 - retina;
15 - the optic disc;
16 - optic nerve
a., aa. — arteria, arteriae (artery, the artery)
lig., ligg. — ligamentum, ligamenta (ligament, the ligaments)
m., mm. — musculus, musculi (muscle, the muscle)
n., nn. — nervus, nervi (nerve, the nerve)
r., rr. — ramus, rami (branch)
s. — seu (or)
v., vv. — vena, venae (vienna)