

THE TUNICS OF THE EYE 



1009 





spaces of the angle of the iris (spaces of Fontana); they communicate with the sinus venosus 

 sclerse and with the anterior chamber at the filtration angle. Some of the fibers of this trabecular 

 tissue are continued into the substance of the iris, forming the pectinate ligament of the iris; 

 while others are connected with the forepart of the solera and choroid. 



The endothelium of the anterior chamber (endothelium camerce anterioris; posterior layer; 

 corneal endothelium) covers the posterior surface of the elastic lamina, is reflected on to the 

 front of the iris, and also lines the spaces of the angle of the iris; it consists of a single stratum 

 of polygonal, flattened, nucleated cells. 



Vessels and Nerves. The cornea is a non-vascular structure; the capillary vessels ending in 

 loops at its circumference are derived from the anterior ciliary arteries. Lymphatic vessels have 

 not yet been demonstrated in it, but are 

 represented by the channels in which the 

 bundles of nerves run; these channels are 

 lined by an endothelium. The nerves are 

 numerous and are derived from the ciliary 

 nerves. Around the periphery of the cor- 

 nea they form an annular plexus, from 

 which fibers enter the substantia propria. 

 They lose their medullary sheaths and 

 ramify throughout its substance in a deli- 

 cate net-work, and their terminal filaments 

 form a firm and closer plexus on the sur- 

 face of the cornea proper, beneath the 

 epithelium. This is termed the subepithe- 

 lial plexus, and from it fibrils are given off 

 which ramify between the epithelial cells, 

 forming an intraepithelial plexus. 



The Vascular Tunic (tunica vascu- 

 losa oculi) (Figs. 872, 873, 874). 

 The vascular tunic of the eye is 

 formed from behind forward by the 

 choroid, the ciliary body, and the iris. 



The choroid invests the posterior 

 five-sixths of the bulb, and extends 

 as far forward as the ora serrata of 

 the retina. The ciliary body connects 

 the choroid to the circumference of 

 the iris. The iris is a circular diaphragm behind the cornea, and presents near 

 its center a rounded aperture, the pupil. 



Anterior ciliary artery 



FIG. 872. The choroid and iris. (Enlarged.) 



Short ciliary arteries 



Anterior ciliary artery 



FIG. 873. The arteries of the choroid and iria. The greater part of the solera has been removed. (Enlarged.) 



The Choroid (chorioidea) . The choroid is a thin, highly vascular membrane, of 

 a dark brown or chocolate color, investing the posterior five-sixths of the globe; 





