560 



THE ORGANS 







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outer meridional group lying next to the sclera and known as the 

 tensor choricidese, and (c) a middle radial group. The meridional 

 and radial groups both take origin in the posterior elastic lamina of 

 the cornea, the former passing backward along the margin of 

 the sclera to its insertion in the ciliary body near the era serrata, the 

 latter radiating fan-like to a broad insertion in the ciliary body and 

 processes. 



The cihary body is closely attached to the sclero-corneal junction 

 by the ligamentum pectinatum (Fig. 371), a continuation of the 



posterior elastic lamina of the 

 cornea. Within the ligament are 

 spaces {spaces of Fontana) hned 

 with endothelium. These are ap- 

 parently lymph spaces, and com- 

 municate with each other, with 

 similar spaces around the canal of 

 Schlemm, and with the anterior 

 chamber. The canal of Sclilemm 

 (Fig. 371) is a venous canal which 

 encircles the cornea, lying in the 

 sclera close to the corneal margin. 

 Instead of a single canal there may 

 be several canals. 



The Iris (Fig. 372). — This 

 represents a further continuation 

 forward of the chorioid. Its base 

 is attached to the cihary body and 

 ligamentum pectinatum. From 

 tliis point it extends forward as a 

 diaphragm in front of the lens, its centre being perforated to form the 

 pupillary opening. It is deeply pigmented, and to its pigment the 

 color of the eye is due. Four layers may be distinguished, which 

 from before backward are as follows: 

 (i) The anterior endothelium. 



(2) The stroma. 



(3) The vitreous membrane. 



(4) The pigmented epithelium. 



(i) The anterior endothelium is a single layer of pigmented cells 

 continuous with the posterior endothelium of the cornea (Fig, 

 364, a). 



Fig. 372. — Vertical Section through 

 Iris. (Merkel-Henle.) a, Anterior en- 

 dothelium; 6, stroma or substantia pro- 

 pria; c. vitreous membrane; d, pigment 

 layer; v, blood-vessel. 



