THE CHOROID COAT. 



27 



The inner part of the choroid coat (tunica Ruyschiana s. chorio-capillaris, 

 fig. 29) is formed mainly by the capillaries of the choroidal vessels. From the 

 ends of the arteries the capillaries radiate and form meshes which are closer than in 

 almost any other texture, being especially fine at the back of the eyeball, near the 

 yellow spot. The network reaches as far forwards as the ora serrata, where its 

 meshes become elongated, and join those of the ciliary processes. 



The capillaries are embedded in a soft almost homogeneous tissue, and are stated 

 to be enclosed within extensions of the perivascular lymph-spaces of the choroidal 

 veins. 



Fig. 33. DIAGRAMMATIC REPRESENTATION OF THE COURSE OF THE VESSELS IN THE EYE. HORIZONTAL 



SECTION. (Leber. ) ARTERIES AND CAPILLARIES RED; VEINS BLUE. 



0, entrance of optic nerve ; a, short posterior ciliary arteries ; a', branch to the optic nerve ; 6, 

 long posterior ciliary arteries ; c, anterior ciliary vessels ; d, posterior conjunctival vessels ; d', anterior 

 conjunctival vessels ; e, central vessels of the retina ; /, vessels of the inner sheath of the optic nerve ; 

 </, vessels of the outer sheath ; h, vorticose vein ; i, short posterior ciliary vein ; I, anastomosis of 

 choroidal vessels with those of optic nerve ; m, chorio-capillaris ; n, episcleral vessels ; o, recurrent 

 artery of the choroid ; p, circulus iridis major (in section) ; g, vessels of iris ; r, vessels of ciliary 

 process ; s, branch from ciliary muscle to vorticose vein ; t, branch from ciliary muscle to anterior 

 ciliary vein ; u, canal of Schlemm ; v, capillary loop at margin of cornea. 



Fig. 34. VESSELS OF THE CHOROID, CILIARY PROCESSES, AND IRIS OF A CHILD. (Arnold.) 



Magnified 10 times. 



a, capillary network of the posterior part of the choroid, ending at b, the ora serrata ; c, arteries of 

 the corona ciliaris, supplying the ciliary processes, d, and passing into the iris, e ; f t the capillary net- 

 work close to the pupillary margin of the iris. 



The veins begin by the convergence of the choroidal capillaries in a whorl-like 

 manner (fig. 32) to form venous tributaries, which themselves converge again in a 

 similar manner to form the large whorled veins or vense vorticosae, by which 

 the blood is conveyed away from the choroid coat. 



