BLOOD VESSELS OF THE EYE. 373 



muscles, penetrate the sclera near the cornea, and in part join the circulus 

 iridis major, in part supply the ciliary muscle, and in part through recurrent 

 branches, connect with the lamina choriocapillaris. Before penetrating 

 the sclera the anterior ciliary arteries give off posteriorly branches for the 

 anterior half of the sclera, and anteriorly branches for the conjunctiva 

 bulbi and the corneal border. The cornea itself is without vessels, but at 

 its border, between the anterior lamellae of the substantia propria, there 

 are terminal loops. 



The veins generally proceed toward the equator, uniting in 4 

 (less often in 5 or 6) venae vorticosae. These pass directly through the 

 sclera and empty into one of the ophthalmic veins. Besides the venae 

 vorticosae there are small veins accompanying the short posterior and the 

 anterior ciliary arteries. The short ciliary veins receive branches from 

 the ciliary muscle, the episcleral vessels, the conjunctiva bulbi and the 

 periphery of the cornea. The episcleral veins also connect with the venae 

 vorticosae. Within the sclera near the cornea there is a circular vein 

 receiving small branches from the capillaries of the ciliary muscle. This 

 sinus venosus sclerae [canal of Schlemm] connects with the anterior ciliary 

 veins. 



Arteria centralis retinae. From 15 to 20 mm. from the eye the central 

 artery of the retina passes to the axis of the optic nerve and proceeds to the 

 the optic papilla. There it divides into two branches directed upward 

 and downward respectively, and these by further subdivision supply the 

 entire pars optica retinae. The branches are chiefly in the inner layers 

 but may extend into the outer reticular layer; they are absent from the 

 fundus of the fovea centralis. Within the optic nerve the artery sends out 

 numerous little branches which anastomose with small vessels which have 

 entered the sheaths from the surrounding fat; and also with branches of 

 the short posterior ciliary arteries (Fig. 425, b). 



The central vein of the retina receives two main branches at the optic 

 papilla and follows the artery along the axis of the optic nerve. 



CHAMBERS AND SPACES OF THE EYE. 



The eye contains no lymphatic vessels but is provided with communi- 

 cating tissue spaces, bounded by mesenchymal cells or epithelia. These 

 include the canaliculi of the cornea and sclera; and the anterior chamber 

 of the eye which through the capillary interval between the lens and iris 

 connects with the posterior chamber, and the latter is prolonged into the 

 zonular spaces. Irregular extensions of the anterior chamber, associated 

 with the pectinate ligament of the iris, are called spaces of the angle of the 

 iris [spaces of Fontana]. They are but slightly developed in man. Pos- 



