Selasa, 22 Februari 2011

Anatomy Retina

The retina is a thin sheet of nerve tissue that semitransparan, and multilapis and line the inside of two thirds of the posterior wall of the eyeball. The retina is often called the retina, is part of the eye contains receptors that receive light stimuli.
Bounded by the choroid and retina pigment epithelial cells of the retina, and consists of layers, ranging from the inside, is as follows:
1. Internal limitans membrane
2. Layer of nerve fibers
3. Layer of ganglion cells
4. Pleksiform layer in
5. In the nuclear layer
6. Pleksiform outer layer
7. Outside the nuclear layer
8. Internal limitans membrane
9. Photoreceptor layer
10. Pigment epithelial layer
In the middle there is the posterior retina macula. In clinical can be defined as an area of yellowish pigmentation caused by luteal pigment (xantofil), and bordered by arcades-temporal retinal vascular arcades. In the middle of the macula, approximately 3.5 mm lateral to the optic disc, fovea that clinically there is clearly a reflection of a basin that provides specially when done oftalmoskop.
 
Fovea is marked with the depletion layer and the outer core and the absence of the layers of parenchyma because of photoreceptor cell axons run in a centrifugal oblique and shifting layers of the retina that is closer to the surface of the retina. Foveola is the most central part of the fovea, here fotoreseptornya are cone cells and is the thinnest part of the retina.
On funduscopic the macula lutea appear redder than its surroundings and on the central fovea as if no light reflex, called the fovea, which is caused by the curvature at the central fovea. In the nasal part of macula lutea contained Nervi optisi papilla, which is a place where N. II through the sclera. Papil is only composed of nerve fibers, did not contain stem cells or cone at all and called the blind spot.
Indentation in the middle there that looked a little pale, from where this is out of central retinal artery and vein which then ramify into the temporal and the nasal, as well as upwards and downwards. The artery is a terminal artery and no anastomose. But sometimes in to anastomose between a. Siliaris and a. Central retina, called a. Silioretinal located in the macula, so that in case of emboli that enter the central retinal artery of macular function undisturbed.
Suppliers main artery to the orbit and their parts derived from arterial oftalmika, the first major branch of the intracranial internal carotid artery. This branch runs below the optic nerve and optic canal with him through to the orbita. The first intraorbital branch is the central retinal artery, which enter the optic nerve about 8-15 mm behind the eyeball. Retinal blood vessels out in papil N. II, forming a picture of the different branches on each individual.
The retina receives blood from two sources. Usually the inside of the retina is supplied by central and branch a.retina memperdarahi inner two thirds. On the outside is supplied by koriokapiler which is right outside the Bruch membrane, which memperdarahi outer third of the retina. Includes outer layer pleksiformis and outer core layer, photoreceptors, and retinal pigment epithelial layer.

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