. Quain's elements of anatomy . and the spacesof Fontana, and its fibres,spreading out, are directedbackwards (fig. 332, k),to be inserted into thechoroid opposite to theciliary processes, andpartly further back. Neartheir insertion the fibrespass equatorially and in-ter-cross so as to formpecuhar stellate to Waldeyer,a small portion (theoutermost) is sometimesinserted into the sclerotic coat (fig. 332, m). These antero-posterior, ormeridional and radiating fibres, pass at the side next the iris into a ring offibres (l), which have a circular course around the insertion of th
. Quain's elements of anatomy . and the spacesof Fontana, and its fibres,spreading out, are directedbackwards (fig. 332, k),to be inserted into thechoroid opposite to theciliary processes, andpartly further back. Neartheir insertion the fibrespass equatorially and in-ter-cross so as to formpecuhar stellate to Waldeyer,a small portion (theoutermost) is sometimesinserted into the sclerotic coat (fig. 332, m). These antero-posterior, ormeridional and radiating fibres, pass at the side next the iris into a ring offibres (l), which have a circular course around the insertion of the set forms the circular ciliary muscle of H. Miiller. This circularmuscle is much developed in hypermetropic eyes, but is atrophied, ormay even, it is said, be absent in myopic (Iwanoff). The ciliary muscle,at least its inner part, was formerly described as the ciliary liyament. Inbirds the ciliary muscle is composed of cross-striped muscular fibres. The nerves of the choroid will be described with those of the The THE IRIS. iris is the contractile and coloured membrane ^vhich is seen In its behind the transparent cornea,, and gives the tint to the eyecentre it is perforated by an aperture—the 2nipil. At its circumferential border, Avhich is nearly circular, the iris is THE lEIS. 405 continuous with the choroid, and by the ligamentum pectinatum, withthe cornea : the free inner edge is the boundary of the pupil. The irismeasures half an inch across, and, in a state of rest, about one-fifth ofan inch from the circumference to the pupil. The anterior surface,yariously coloured in different eyes, is marked by waved lines couTergingtowards the pupil, near which they join in a series of irregular eleva-tions ; and, internal to these, other finer lines pass to the pupil. Theposterior surface is covered with dark pigment, and is marked by anumber of fiiie converging folds or thickenings prolonged from thecihary processes. Pig. 339. Fig. 340.
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
