Quain's elements of anatomy . 2, cells forming the pars ciliaris. pointed, square, or even branched ; thesides of the cells, too, are sometimesuneven. These cells are considered by Kollikerto correspond with the Miillerian fibresof the retina, but according to Sohwalbe 2the Miillerian fibres, or rather theirunited inner ends, are represented by a delicate membrane, which covers the inner ends of the columnar cellsand sends fine offsets around and between them. Vessels of the Ketina.—A single artery {arteria centralis retinm)passes between the bundles of fibres of the optic nerve to the innersu
Quain's elements of anatomy . 2, cells forming the pars ciliaris. pointed, square, or even branched ; thesides of the cells, too, are sometimesuneven. These cells are considered by Kollikerto correspond with the Miillerian fibresof the retina, but according to Sohwalbe 2the Miillerian fibres, or rather theirunited inner ends, are represented by a delicate membrane, which covers the inner ends of the columnar cellsand sends fine offsets around and between them. Vessels of the Ketina.—A single artery {arteria centralis retinm)passes between the bundles of fibres of the optic nerve to the innersurface of the retina at the middle of the papilla optici (fig. 345, a). Itis accompanied by the corresponding vein and soon divides into branches(fig. 344), usually two, one above, the other below, each of these againdividing into two branches which arch out towards the sides ; the outerones are somewhat the larger, and as they bend round the macula luteathey send numerous fine branches into it which end at the margin of the. 422 THE EYE fovea centralis in capillary loops. The main branches of the vessels passfoiAvards in the nerve-fibre and ganglionic layers, dividing dichotomouslyas they proceed, and giving off fine offsets to the substance of the retina,where they form two capillary networks, the one in the nerve- and gang ?lionic layer, the other in the inner nuclear layer. The capillaries of theformer are mainly connected with the arteries, and those of the latter mththe veins, the communication between the two networks being effectedby vertically and obliquely coursing capillaries which traverse the innermolecular layer. No vessels penetrate the outer molecular layer (His,Hesse), so that the outer retinal layers are entirely destitute of blood-vessels. The vascular system of the retina is nowhere in direct commimication -with thechoroidal vessels. Near the entrance of the optic nerve, however, it conies intocommimication with some offsets from the sclerotic coat, and the
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
