It is important for your Cape Girardeau Chiropractor to be familiar with this information. This coat is formed by the nervous tissue, which does notextend over the entire sphere, but rather is found just inside thechoroid coat, lining the posterior five-sixths of the globe. Theretina is a spread out fan formation of the optic nerve from itspoint of entrance into the eye of its anterior termination in asaw-like border, known as the ora serrata. It is thicker at itsposterior than at its anterior, because of the fact that its fibers areterminating throughout the entire surface, and thus their number iscontinually decreasing. At the posterior of the retina, Lyingdirectly in the visual axis is a yellow spot called the macula lutea,in the center of which is a depression, which is known as the foveacentralis. It is at this part of the retina that the sense of vision ismost keen, due undoubtedly to the presence here of aproportionately greater quantity of end cells of sight than are foundin any other part. Situated slightly toward the internal and belowthis spot is the point of entrance of the optic nerve, with a slightelevation at its circumference, called the optic elevation, and witha depression in the center, called the optic cup. At this point theend cells of vision are entirely absent, hence it is called the blindspot or optic disc.The retina is formed of eleven distinct layers, but as we areonly concerned with that layer wherein are contained the end cellsof the sense of sight we shall describe only that. Considering thelayers as numbered from within outward, the tenth is the onewhich contains the rods and cones which are the end cells ofsight. These cells with their supporting framework form Jacob’smembrane, and they are so named from their peculiar shapes. Therods are more numerous than the cones and consist of a rod bodyand a rod fiber, the former being external and the latter extendingfrom the inner end of the rod into the fifth layer, where it isconnected with direct fibers from the optic nerve. Knowing physiology will allow your Cape Girardeau Chiropractor to help their patients.