670 THE EYE 



attached in the grooves between the processes. From the sides of these 

 processes fibers 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 anteriorly. 

 These fibers form the suspensory ligament of the crystalline lens (Figs. 

 543 and 565). 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 ciliaris (of Zinn). 



The glassy fibers 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 capsule to which they 

 are intimately adherent. The fibers arising more posteriorly are said 

 to be attached to the lens anteriorly to the equator, those arising from 

 the more anterior portions of the ciliary processes becoming attached 

 posteriorly to the equator of the lens. 



The most anterior of these fibers form a somewhat plicated but in- 

 complete membrane which serves as the anterior boundary of an annular 

 series of connecting lymphatic spaces collectively .forming the spatia 

 zonularis (canals of Petit). This irregularly sacculated, annular canal 

 is bounded posteriorly by the hyaloid membrane, anteriorly by the in- 

 complete membranous wall of the posterior chamber through which the 

 aqueous humor readily diffuses, internally by the margin of the crystal- 

 line lens, and antero-externally by the ciliary processes. Besides sup- 

 porting the lens, the suspensory ligament assists in the accommodation 

 of the lens to far and near vision, a process involving a change of con- 

 vexity, and dependent upon the activity of the ciliary muscle. 



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, en- 

 ters the optic nerve about midway between the optic commissure and 

 the ocular globe, and arriving at the center of the nerve runs in its axis 



