414 



DIGESTIVE SYSTEM OF THE HORSE 



forming the visceral peritoneum for the first part of that tube.^ Laterally it is 

 reflected in a similar fashion. If the rectum be raised, it will be seen that the 

 peritoneum passes from its ventral surface and forms a transverse fold which lies 

 on the dorsal surface of the bladder (Fig. 370). This is the genital fold (Plica 

 genitalis). Its concave free part passes on either side into the inguinal canal. 

 The ventral layer of this fold is reflected on to the dorsal surface of the bladder. 

 Thus there is formed a pouch between the rectum and bladder — the recto-vesical 

 pouch (Excavatio recto-vesicalis), which is partially subdivided by the genital 

 fold into recto-genital and vesico-genital cavities. The fold contains the ductus 

 deferentes, part of the vesiculse seminales, and the uterus masculinus (a foetal 

 remnant) . If the bladder is now raised, it is seen that the peritoneum passes 



Left extremity 



CEsophagics 



Duodenum. 

 Pylorus 



Antrum pyloricum 



Fig. 354. — Stomach of Horse; Parietal Surface. 



The organ was fixed in situ when well filled. The lesser curvature has been opened up slightly and the peritoneum, 



etc., in this ^dcinity removed. The larger branches of the anterior gastric artery and vein are visible. 



from its ventral surface on to the pelvic floor, forming centrally the median um- 

 bilical fold or middle ligament of the bladder (Plica umbilicalis media). It also 

 passes from each side of the bladder to the lateral pelvic wall and forms thus 

 the lateral umbilical fold or ligament of the bladder (Plica umbilicalis lateralis) ; 

 this contains in its edge the so-called round ligament of the bladder (Ligamentum 

 teres vesicae) — the partially occluded umbilical artery, which is a large vessel 

 in the foetus.^ 



In the female the arrangement is modified by the presence of the uterus; 



1 The point at which the reflection takes place is quite variable, and apparently depends 

 chiefly on the amount of feces in the rectum. When the bowel is very full the reflection may be 

 little behind the promontory; when it is empty, the reflection may be at the posterior end of the 

 sacrum. 



" In the f cetus and new-born foal these three folds extend to the umbilicus in conformity with 

 the abdominal position of the bladder. When the latter becomes a pelvic organ, the lateral folds 

 conform to the change and end at the vertex of the bladder. The median fold may still be trace- 

 able to the umbilicus. 



