356 



DIGESTIVE SYSTEM OF THE HORSE 



fold (Plica urogenitalis). Its concave free edge passes on either side into the in- 

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

 of the bladder near its neck. Thus there is formed a pouch between the rectum 

 and bladder — the recto-vesical pouch (Excavatio recto-vesicalis), which is partially 

 subdivided by the urogenital fold into recto-genital and vesico-genital cavities. 

 The fold contains the vasa deferentia, part of the vesiculae seminales, and the 

 uterus masculinus (a foetal remnant). The space on either side of the rectum is 

 occupied by coils of the small colon and the pelvic flexure of the great colon usually. 

 If the bladder is now raised, it is seen that the peritoneum passes from its ventral 

 surface on to the pelvic floor, forming a median fold, the so-called middle ligament 

 (Plica umbilicalis media). It also forms on each side a lateral fold, the lateral 



Saccus coecus {left extremity) 



Area of attachment to dia- 

 phragm {non-peritoneal) 



Bile-duct 



Fig. 258. — Stomach op Horse, P.\^rietal Surface, with First Part op Duodenum. 

 Fixed in situ when full but not distended. The larger branche.s of the anterior gastric artery with two satellite 



veins are shown. 



ligament (Plica umbilicalis lateralis), which contains in its edge the so-called round 

 ligament (Ligamentum teres) — 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; 

 the urogenital fold is very large, so as to inclose the uterus and a small part of the 

 vagina. It forms two extensive folds, the broad ligaments of the uterus (Liga- 

 menta lata uteri), which attach that organ to the sides of the pelvic cavity and the 

 lumbar part of the abdominal wall (Fig. 271). It thus divides the recto-vesical 

 pouch completely into dorsal and ventral compartments — the recto-genital pouch 

 (Excavatio recto-uterina), and the vesico-genital pouch (Excavatio vesico-uterina). 



Further details will be given in the description of the pelvic viscera. 



