BLOOD VESSELS OF THE EYE 597 



consists of delicate glassy fibres so disposed as to form an extremely 

 thin reticular membrane. 



This membrane passes forward over the inner surface of the 

 retina, to which it is loosely united, until at the ora serrata its 

 fibres leave the retinal surface and pass inward to the margin of 

 the lens to become firmly adherent to the posterior surface of the 

 lenticular capsule. 



THE SUSPENSORY LIGAMENT. Certain fibres from the 

 hyaloid membrane pass forward from the ora serrata and are firmly 

 adherent to the ciliary processes. From the sides of these processes 

 fibres diverge at frequent intervals and pass to the margin of the 

 lens, where they are attached on either side of the equator, spread- 

 ing over a zone which is somewhat narrower posteriorly than ante- 

 riorly. These fibres form the suspensory ligament of the crystalline 

 lens (Figs. 422 and 438). They occupy an annular zone which is 

 included between the ciliary processes and the margin of the lens, 

 and which is known' as the zonula of Zinn. 



The glassy fibres of this ligament take origin from the sides of 

 the ciliary processes along which they are firmly attached, becoming 

 free only near the apices of these processes. They pass thence to 

 the margin of the lens and spread out upon the surface of the cap- 

 sule to which they are intimately adherent. 



The most anterior of these fibres form a somewhat plicated but 

 incomplete membrane which serves as the anterior boundary of an 

 annular series of connecting lymphatic spaces collectively forming 

 the spatia zonularis (canal of Petit). This irregularly sacculated, 

 annular canal is bounded posteriorly by the hyaloid membrane, ante- 

 riorly by the incomplete membranous wall of the posterior chamber 

 through which the aqueous humor readily diffuses, internally by 

 the margin of the crystalline lens, and antero-externally by the 

 ciliary processes. 



BLOOD VESSELS OF THE EYE 



The circulation of blood in the globe of the eye is maintained 

 through four sets of vessels : 



1. The arteria and vena centralis retinae. 



2. The short ciliary arteries and venae vorticosae. 



3. The long ciliary arteries. 



4. The anterior ciliary arteries and veins. 



1. The arteria centralis, destined for the supply of the retina, 

 enters the optic nerve about midway between the optic commissure 



