CHAPTER XII. 



THE CHOROID. 



The Choroid is a thin, dark-colored membrane situated 



between the sclera and the retina. Extends from corpus 



cili are to the optic nerve. Made up of vessels, pigment, 



and some connective tissue. The blood comes from 



the short posterior ciliary arteries which anastomose 



with the long posterior and anterior ciliary arteries. 



The veins begin as capillaries and take on a peculiar 



form. Resemble as much as anything else a weeping 



willow, and these uniting, form the venae vorticosse, 



emptying into the opl^thalmic vein. The anterior 



ciliary vein drains the anterior portion. The long 



and short ciliary nerves form plexuses in the 



choroid and contain a number of ganglionic cells. 



Between the retina and choroid there is a layer 



of pigmented epithelium. The inner face of the 



choroid is not uniform in color, being perfectly 



black in the lower part of the eye. This is abruptly 



terminated at a horizontal line about the eighth or 



ninth part of an inch above the optic papilla. Froni 



this line on the segment of a circle from i% to i% of an 



inch in height, it shows most brilliant colors ; at first 



105 



