THE EYE AND ITS ATPENI'-IGES 241 



capillary endings of the vessels of the outer coat ; they pass 

 forwards to inch from the cornea, joining those of the 

 ciliary processes. 



The Ciliary Body consists of the ciliary processes and the 

 ciliary muscle. 



The ciliary processes are of the same structure as the rest 

 of the choroid. They are about seventy in number, and are 

 placed in corresponding depressions upon the surface of the 

 vitreous humour, and upon the suspensory ligament of the lens. 

 The bloodvessels are derived from the anterior ciliary branches. 



The ciliary muscle consists of two sets of involuntary 

 muscular fibres, radiating and circular. (Nerve supply from 

 3rd cranial.) 



The radiating arise by tendon from the sclerotic close to the 

 junction with the cornea, between the spaces of Fontana and 

 the canal of Schlemm, and are inserted into the choroid 

 opposite the ciliary processes. 



The circular: a zone of circular fibres internal to the 

 radiating, at the base of the ciliary processes. 



The iris is the coloured membrane suspended in the aque- 

 ous humour behind the cornea and in front of the lens. In 

 the centre is an aperture, the pupil. 



It is connected at its circumference to the choroid, being 

 continuous with it ; and anterior to this it is attached to 

 the cornea by the pillars of the iris, or ligamentum pec- 

 tinatum. 



The anterior surface is coloured and marked by wavy lines 

 converging towards the free edge of the pupil. 



The posterior surface is darkly pigmented (uvea] and 

 marked with folds prolonged from the ciliary processes. 



The framework of the iris is a delicate stroma of connec- 

 tive-tissue, containing bloodvessels, nerves, pigment cells, 

 and two groups of involuntary muscular fibres : 



The sphincter, a narrow band of fibres placed posteriorly 

 close to the pupil (3rd nerve) . 



The dilator, commencing at the outer margin of the iris, 

 with the fibres converging towards the pupil (sympathetic 

 nerve). 



The bloodvessels of the iris consist of the two long ciliary and 

 the anterior ciliary arteries ; the former pierce the sclerotic 

 close to the optic nerve, and pass forwards in the lymph- 

 space between the lamina fusca of the sclerotic and the lamina 

 supra-choroidea of the choroid to enter the outer surface of 

 the iris, having previously divided into two branches. They 

 anastomose with the corresponding vessels of the opposite 



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