NERVES OF THE CORNEA. 



597 



vessel, 5, leading from it ; 6, otlier vessels ; 7, bundles of fibres of tlie sclerotic running 

 cquatorially, cut across ; 8, larger ones in tlie substance of the sclerotic ; 9, fine bundles 

 cut across, at limit of cornea ; 10, point of origin of meridional bundles of ciliar\- 

 muscle ; 11, blood-vessels in scleroti3 and conjunctiva, cut across ; 12, section of one 

 of tlie ciliary arteries. 



Vessels and nerves. — In a state of health the cornea is not provided 

 with blood-vessels, except at the circumference, where they form very fine 

 capillary loops and accompany the nerves. Neither are any lymphatic 

 vessels discoverable, unless the channels in which the nerves run, and 

 which are lined with flattened cells and in connection with the cell spaces, 

 are to be taken as representing them. The nerves, on the other hand, are 

 very numerous. Derived from the ciliary nerves, they enter the fore part 

 of the sclerotic, and are from forty to forty-five in number (Waldeyer). 

 Continued into the fibrous part of the cornea, they retain their dark 

 outline for ^^^th to y^jtli of an inch, and then, becoming transparent, 

 ramify and form a plexus through the laminated structure. From this 

 lirimary plexus other nerves proceed to form a much finer and closer 

 plexus — but of which the cords yet consist of several nerve-fibrils — 

 at the surface of the cornea, immediately beneath the epithelium, and 

 from this secondary or siibepifhcllal jj/p;i'//s excessively fine, varicose, 

 ultimate fibrils (fig. 404, h) pass among the epithelium cells, and form 

 here a terminal network, the intra-cpithelial plexus, which extends almost 

 to the free surface (fig. 40-4, c, c). 



Fig. 40i. 



Fig. 404. — Intra-epithelial Plexus op Cornea of Rabbit, stained by Chloride 

 OF Gold. Oblique view. 300 Diameters (Klein). 



o, part of subepithelial plexus ; b, h, tufts of fine varicose fibrils ; c, network of 

 these amongst, d, the deeper epithelial cells. 



In addition to the nerves which are destined for the epithelium, 

 others, for the proper substance of the cornea, come off from the 

 primary plexuses, and, after uniting into one or more secondary 

 plexuses, the cords of which are still composite, eventually form, iu 

 and among the lamina, a terminal network of ultimate fibrils, the 

 meshes of which are much more open than those of the intra-epithelial 

 network. An actual connection of the nerves with the corpuscles of 

 the cornea has never been satisfactorily shoAvn. 



