342 



NORMAL HISTOLOGY. 



to the pupil and includes three portions, which from behind forward are: the 



choroid, the ciliary body, and the iris. The choroid and ciliary body are in 



contact with the sclera, but the iris bends sharply inwards and floats in the 



aqueous humor, incompletely 



dividing the space anterior Membrana vit rea ^ ,^__^^^gBBg 



to the crystalline lens into 



the posterior and the anterior 



chamber. 



The Choroid. The cho- 

 roid contributes the posterior 

 two-thirds of the vascular coat. 

 It lies between the sclera and 

 the retina and extends from 

 the optic nerve entrance to 

 the anterior limit of the visual 

 part of the retina at the ora 



serrata, its main function being to supply nutrition to the nervous tunic. 

 It is a delicate coat, with a thickness of . 2 mm. near the nerve and about 

 half as much at the ora serrata. The outer surface is roughened by the 







.: "- ".* ^ ^S^ 



Choriocapillaris - 

 Large vein- 



Choroidal stron 

 Lamina suprachorioidea 



Suprachoroidal space - 

 Lamina fusca of sclera- 



FIG. 389. Section of choroid, showing capillary layer and 

 large vessels. X 200. 



Large vein 



Arter 



FIG. 390 Surface view of injected human choroid, showing venous radicles converging to form large 



vein. X 18. 



trabeculae of connective tissue which cross the suprachoroidal lymph-space 

 and connect the choroid with the overlying sclera. Its inner surface 

 is smooth and covered by the pigmented cells of the retina, which are so 

 closely attached that they frequently adhere to the choroid when the mem- 

 branes are separated. 



