I5IO A MANUAL OF ANATOMY 



The successive laminae are connected by cement substance, and 

 within this substance there are branched spaces, called the corneal 

 spaces or lacunae, which communicate with each other by very 

 delicate canaliculi. Each of these spaces contains a nucleated 

 connective- tissue corpuscle, called the corneal corpuscle. These 

 corpuscles, like the spaces which they occupy, are branched, and 

 the offsets of adjacent corpuscles communicate with one another. 

 As seen in vertical sections of the cornea the corpuscles are spindle- 

 shaped, but in horizontal sections they appear flattened out, and 

 give off their branches. 



The posterior elastic lamina, or membrane of Descemet (mem- 

 brane of Demours), covers the posterior surface of the substantia 

 propria. It is thicker than the anterior elastic lamina, and is 

 composed of an elastic homogeneous membrane, which is very 

 brittle. When stripped from the substantia propria it comes 

 away in shreds, and these curl up at their ends in such a manner 

 that the anterior or attached surface of each shred is turned inwards. 

 At the circumference of the cornea the posterior elastic lamina 

 becomes broken up into fibres. The most posterior of these fibres 

 pass in a radiating and reticular manner into the iris, and they 

 form the ligamentum pectinatum iridis, the intervals between the 

 fibres of which represent the spaces of Fontana. 



The layer of endothelium lines the posterior surface of the posterior 

 elastic lamina, and consists of one stratum of cells. It is continued 

 over the front of the iris, and into the spaces of Fontana. 



The cornea in the adult is non-vascular, except at the circum- 

 ference, in which situation there are the conjunctival and sclerotic 

 capillaries, which terminate in loops. Being destitute of blood- 

 vessels, the nourishment of the cornea is maintained by the flow 

 of lymph through its substance. 



Nerve-supply. — The nerves are derived from the ciliary nerves, 

 and are very numerous. They enter the anterior part of the 

 sclerotic, and form a plexus around the corneo-scleral junction. 

 Offsets from this plexus enter the cornea, and form what is known 

 as the plexus annularis. From this plexus delicate offsets are 

 given off, which traverse the substance of the cornea and pass 

 through the anterior elastic lamina. They then give rise to a fine 

 plexus upon the surface of that lamina, called the subepithelial 

 plexus. From this plexus, in turn, minute fibrils are given off, 

 which pass amongst the cells of the conjunctival epithelium, and 

 almost reach the surface, forming an intra-epithelial plexus. 



Ligamentum Pectinatum Iridis. — As stated, the posterior elastic 

 lamina at its circumference breaks up into fibres. The most 

 posterior fibres, which pass in a radiating and recfcicular manner 

 into the iris, constitute the ligamentum pectinatum iridis, and they 

 are covered by a prolongation of the endothelial layer of the cornea. 



Spaces of Fontana. — These spaces represent the irregular intervals 

 which lie between the radiating and reticular fibres of the liga- 

 mentum pectinatum iridis. They are lined by a prolongation 



