266 SPECIAL ANATOMY. 



Henle it does not exist ; but there is only to be found in this situation a 

 loose, delicate, uniting tissue with pigment cells. 



b. The central, vascular, and coloured layer of the coats of the 

 eye. 



499. 3. Choroidea s. tunica vasculosa, 



a thin, very vascular tunic of the same extent as the sclerotica, to the internal 

 surface of which it is attached by a delicate, brown, uniting tissue (see AracL 

 oculi). Both surfaces, but especially the internal, on which the Retina lies, 

 are covered by a deposit of black pigment which consists of mosaic-like, 

 angular, or roundish cells, and is provided with innumerable convoluted longi- 

 tudinal stria; which correspond to vessels. What has been described as lamina 

 fusca scleroticas, is probably identical with the pigment deposit on the external 

 surface of the choroid. Behind, this membrane is perforated by a circular 

 foramen for the passage of the optic nerve. The choroid has been artificially 

 divided into an external (venous) layer, and an internal (arterial, membran. 

 Ruyschiana) ; of which we may assume the former to form the ligam. ciliare, 

 the latter the corpus ciliare. Vessels : artt. ciliares post, upon the internal 

 surface ; vasa vorticosa (veins) upon the external surface, pass into vv. ciliar. 

 postt. Nerves ; a few ramify in it, most pass through it. (Pappenheim.) 



a. Ligamentum ciliare s. orbicularis ciliaris, the ciliary ligament, a flat, gray 

 and delicate circle, from a line to a line and a half broad, the anterior, smaller 

 and thicker border of which abuts on the point of junction of the cornea and 

 sclerotica and unites with the external border of the iris, whilst the posterior, 

 thinner, and larger border meets the corpus ciliare, and receives the ciliary 

 nerves which divide in the ciliary ligament, going through it (Arnold) or rami- 

 fying in it (Pappenheim). Its external surface lies loosely on the anterior part 

 of the interior of the sclerotica. A vascular rete with large meshes in it, is 

 connected behind with that of the choroid, and passes anteriorly into the iris. 



b. Corpus ciliare, the ciliary body, the internal lamina of the anterior bor- 

 der of the choroid, reaches farther backwards than a, is sharply bounded by a 

 toothed edge from the proper choroid, but which belongs to the zonula Zinnii, 

 turns up from the posterior body of the lig. ciliare inwards to the border of the 

 lens, and forms a flat circle which consists of the 



Processus ciliares, seventy to eighty short folds. These become larger 

 from behind forwards, and they converge ; in the intervals between them cor- 

 responding folds of the zonula Zinnii are placed, whereby both are firmly 

 united with one another, and the ciliary body with the capsule of the lens ; 

 deprived of the pigment layer in their depressions, they appear white. It is 

 said that a circle of (muscular) fibres extends from their free circumference as 

 far as the capsule of the lens ; this is 



Amman 1 s orbiculus capsulo- ciliaris, but which belongs to the zonula Zinnii. 

 A proper membrana pigmenti is even admitted by some, which separates the 

 pigment layer on the posterior surface of the choroid from the Retina, is re- 



