THE CHOROID, CILIARY BODY, AND IRIS 



1097 



Structure. The ciliary processes are similar in structure to the choroid, but the vessels are 

 larger, and have chiefly a longitudinal direction. They constitute the most vascular portion of 

 the eyeball. The processes are covered on their inner surface by two strata of black pigment 

 cells, which are continued forward from the retina, and are named the pars ciliaris retinae (Fig. 

 806). In the stroma of the ciliary processes there are also stellate pigment cells, which, how- 

 ever, are not so numerous as in the choroid itself. 



Cornea 



Iris 



Lens 



FIG. 802. Diagram of the bloodvessels of the eye, as seen in a horizontal section. (Leber, after Stohr.) 



Course of vasa centralia retinae: a. Arteria. a\. Vena centralis retinae. /^. Anastomosis with vessels of outer 

 coats y. Anastomosis with branches of short posterior ciliary arteries. 6. Anastomosis with chorioideal vessels. 



Course of vasa ciliar. postic. brev. : I. Arteriae, and It. Venae ciliar. postic. brev. II. Episcleral artery. Hi. 

 Episcleral vein. III. Capillaries of lamina choriocapillaris. 



Course of vasa ciliar. postic. long.: 1. a. ciliar. post, longa. 2. Circulus iridis major cut across. 3. Branches 

 to ciliary body. 4. Branches to iris. 



Course of vasa ciliar. ant.: a. Arteria. a\. Vena ciliar. ant. b. Junction with the circulus iridis major. 

 c. Junction with lamina choriocapill. d. Arterial, and d\. Venous episcleral branches, e. Arterial, and ei. 

 Venous branches to conjunctiva sclerae. /. Arterial, and fi. Venous branches to corneal border. V. Vena 

 vorticosa. S. Transverse section of sinus venosus sclerae. 



The Ciliary muscle (Bowman's muscle) (m. ciliaris'} (Figs. 806 and 808) con- 

 sists of unstriped fitjires ; it forms a grayish, semitransparent, circular band, about 

 3 mm. (one-eighth of an inch) broad, on the outer surface of the fore part of the 

 choroid, between the choroid and the iris and back of the sclerocorneal junction. 

 It is thickest in front and gradually becomes thinner behind. It consists of two 

 sets of fibres, radial and circular. The radial fibres (Jibrae meridianales) (Figs. 



