544 BULBUS OCULI 



hyaloidea, for the reception of the posterior, convex surface 

 of the crystalline lens. 



The substance of the vitreous body is enclosed within a 

 delicate transparent membrane, which completely envelops 

 it, and receives the name of the hyaloid membrane. Extend- 

 ing forwards through the midst of the vitreous mass, from the 

 region of the optic disc to the crystalline lens, is a minute 

 canal, lined with a tube-like prolongation of the hyaloid 

 membrane, and containing a watery fluid. The canal is termed 

 the hyaloid canal ; it represents the path taken by a branch .of 

 the arteria centralis retinae, which, in the foetus, extends to and 

 supplies the capsule of the lens, but afterwards disappears. 



The hyaloid canal, as a rule, cannot be seen in an ordinary dissection 

 of the eyeball ; but if the " eye-kernel " is shaken up in the picro-carmine 

 solution as recommended by Anderson Stuart, it may sometimes be rendered 

 evident through the staining fluid entering it. It is represented diagram - 

 matically in Fig. 226. 



Zonula Ciliaris (O.T. Zonula of Zinn). Between the 

 corona ciliaris externally and the margin of the lens internally 

 lies a fibrous membrane called the zonula ciliaris. Its 

 peripheral margin is attached to the posterior surfaces of the 

 ciliary processes and the hyaloid membrane, and its central 

 margin is connected with the lens. As it approaches the 

 margin of the crystalline lens, it splits into two parts, viz., an 

 exceedingly delicate, deep lamina, which lines the fossa 

 hyaloidea, and a more superficial, stronger part, which becomes 

 attached to the capsule of the crystalline lens. 



The zonula ciliaris lies subjacent to the ciliary processes, 

 and is radially wrinkled in correspondence with the depres- 

 sions between the processes. Thus, the elevations or wrinkles 

 of the zonula extend into the intervals between the ciliary 

 processes, whilst the ciliary processes in their turn lie in the 

 depressions between the wrinkles of the zonula. When the 

 eye is fresh, these opposing parts are closely adherent. 



The zonula ciliaris is strengthened by radially directed 

 elastic fibres, and the anterior and stronger of the two layers 

 into which it divides is called the suspensory ligament of the 

 lens. It is attached, mainly, to the anterior surface of the 

 capsule of the lens a short distance beyond the margin of that 

 body, but this is not the only attachment of the suspensory 

 ligament. Some of its fibres are attached to the circum- 

 ference or equator of the lens (equatorial fibres), whilst others 



