274 PHYSIOLOGY CHAP. 



central point. The body of the lens has a fibrous structure, and 



FIG. 113. Diagrammatic representation of the course of the blood-vessels in (hi- <-\<-. 



a and b, short posterior ciliary arteries; c, long posterior ciliary arteries; il, d, il, capillary 

 network or chorio-capillaris ; e, arterial twigs that penetrate the optic nerve ; /. anterior 

 ciliary arteries; g, circulus vaseularis iridis major; h, artery of iris; i, circulus vaseularis 

 iiidis minor; k, capillary plexus in region of iris sphincter; I, artery of ciliary process; 

 in, artery of ciliary muscle ; n, recurrent artery of choroid ; o, posterior artery, p, anterior 

 artery of conjunctiva ; q, arterial twig of pericorneal plexus ; r, central artery of retina ; 

 s, artery of inner sheath, i, of outer sheath of optic nerve ; u, sclerotic branch of short ciliary 

 artery ; v, sclerotic branch of anterior ciliary artery ; x, one of the vorticose veins ; y, posterior 

 ciliary veins ; z, central vein of retina ; 1, vein of inner, 2, vein of outer sheath of optic nerve ; 

 3, venous and arterial twigs of choroid, penetrating the optic nerve ; 4, sclerotic vein, opening 

 into a vorticose vein ; 5, anterior ciliary vein ; (>, its sclerotic branch ; 7, veins of pericorneal 

 plexus ; 8, anterior, 0, posterior conjunctiva! veins ; 10, ciliary plexus ; 11, twig uniting it with 

 the anterior ciliary vein ; 12, veins of ciliary muscle, passing into ciliary plexus ; 13, veins of 

 ciliary process ; 14, veins of iris ; 15, veins of ciliary muscle, passing into a vorticose vein. 



consists of fibres which are arranged in concentric layers and lie 



