124 TOPOGRAPHICAL ANATOMY OF THE 



radial folds and grooves. Close to the margin of the crystalline lens 

 the zonule splits into two layers: The thinner of these lines the hyaloid 

 fossa; while the thicker and more anterior layer is connected with the 

 capsule of the lens, and thus forms the suspensory ligament. A very 

 loose and delicate fibrous stroma vitreum, with a huvior vitreus filling 

 its spaces, is enclosed by the hyaloid membrane and lorms the substance 

 of the vitreous body. 



Running through the vitreous body from the optic papilla to the 

 back of the lens is a minute hyaloid canal (canalis hyaloideus) marking 

 the line of the embryonic hyaloid artery (a. hyaloidea), a branch of the 

 central artery of the retina. The canal cannot be detected in the adult 

 eye unless the vitreous body has been stained. 



If a blow-pipe be introduced through the suspensory ligament, a 

 varicose canal surrounding the equator of the lens can be iuflated. 

 This is formed by the zonular spaces (spatia zonularia), bounded in 

 front by the suspensory ligament and behind by the hyaloid membrane. 



Dissection. — The lens must be separated from the vitreous body by 

 cutting thvougli the suspensory ligament. 



The transparent, nearly circular and biconvex crystalline lens (lens 



crystallina), lies between the iris and the vitreous body. A zone 



between the extreme periphery and the centre of the anterior surface 



(facies anterior lentis) is in contact with the iris ; while a variable 



amount of the central part of the surface coincides with the pupil. The 



posterior surface (facies posterior lentis) has a greater curvature than the 



anterior, and is received into the hyaloid fossa of the vitreous body. 



The central points of the surfaces are the anterior and posterior poles 



(polus anterior lentis : polus posterior lentis). Joining the two poles is 



the axis of the lens (axis lentis). The periphery or equator (aequator 



lentis) is in close contact with the ciliary processes. 



If the lens be held up to the light, three fine radiating lines may be 



detected spreading out from the central point of each surface. These 



indicate the planes of contact of the ends of the fibres (fibrse lentis) 



that compose the intimate structure of the lens. When viewed from 



the anterior surface, one of these lines runs vertically upwards from the 



anterior pole ; the other two diverge downwards. On the posterior 



surface one of the lines runs vertically downwards from the pole ; the 



others diverge upwards. 



Covering the surface of the lens is a homogeneous membrane, the 

 capsule (capsula lentis), much thicker over the anterior than over the 

 posterior surface. 



If a fresh lens be crushed between the fingers, it will be easy to 

 demonstrate the presence of a softer cortical substance (substantia 



