240 THE POCKET ANATOMY 



Close to the junction of the cornea with the sclerotic is 

 a small circumferential lymph -space, called the canal oj 

 Schlemm. 



The bloodvessels of the sclerotic are few in number, but near 

 its junction with the cornea there is a vascular zone derived 

 from the anterior ciliary branches of the ophthalmic artery. 



The cornea is the anterior transparent part of the outer 

 coat of the eye-ball, occupying about fc of the circumference 

 of the globe. It projects forward beyond the curvature of the 

 sclerotic, being the segment of a smaller sphere. The posterior 

 surface is concave, and projects further backwards than the 

 anterior convex surface, being overlapped by the edge of the 

 sclerotic ; this surface forms the anterior boundary of the 

 anterior chamber of the eye, containing the aqueous humou-r. 



The cornea is clothed on its anterior convex surface by the 

 conjunctiva, which here consists only of an epithelial layer. 



At the circumference of the cornea some of the fibres which 

 form its stroma are continued backwards and outwards into 

 the choroid, sclerotic, and iris; those going to the iris are 

 called the ligamentum pectinatum iridis or the pillars of the 

 iris; they form an annular meshwork enclosing a series of 

 lymph-spaces (spaces of Fontana) which communicate with 

 the anterior chamber. 



The choroid coat is situated between the sclerotic and the 

 retina, and is the vascular tunic of the eye-ball. It is con- 

 tinued anteriorly into the iris, but before its junction it forms 

 a number of projections, folding inwards, and arranged in a 

 circle, known as the ciliary processes. 



The choroid coat is thickest behind, where it is pierced by 

 the optic nerve. 



Externally it is connected to the sclerotic by loose connec- 

 tive-tissue traversed by vessels and nerves as before described. 

 Internally it is covered by the pigmented cells of the retina. 



The choroid consists of bloodvessels connected together by 

 loose connective-tissue, and containing large branched and 

 pigmented cells. 



It is made up of two layers, an outer and an inner. The 

 outer part contains the larger branches of the vessels. The 

 arteries, the short posterior ciliary, pierce the sclerotic coat 

 close to the optic nerve, pass forwards, and bend inwards to 

 end in the inner layer. 



The veins, vasa vorticosa, are external to the arteries and 

 join together into four or five principal trunks, which pierce 

 the sclerotic midway between the cornea and the optic nerve 



The inner coat, or tunica Ruyschiana, is formed by the 



