THE PELVIC CAVITY 



355 



organs, some fa?tal remnants, muscles, vessels, 

 the fascia pelvis, and in part by the peri- 

 toneum. 



The pelvic peritoneum is continuous in 

 front with that of the abdomen. It lines 

 the cavity as far back as the third or fourth 

 sacral vertebra in the horse, where it is re- 

 flected on to the viscera, and from one organ 

 to another. We may therefore distinguish 

 an anterior, peritoneal, and a posterior, re- 

 troperitoneal part of the cavity. Along the 

 mid-dorsal line it forms a continuation of 

 the colic mesentery, the mesorectum, which 

 attaches the first or peritoneal part of the 

 rectum to the roof. In animals in fair con- 

 dition a considerable quantity of subperi- 

 toneal and retroperitoneal fat is found on 

 the walls and in the various interstices. 



In the male the geneial disposition of 

 the peritoneum here is as follows. If 

 traced along the dorsal wall, it is re- 

 flected at the third or fourth sacral verte- 

 bra on to the rectum, forming the visceral 

 peritoneum for the first jiart of that tube. 

 Laterally it is reflected in a similar fasiiion. 



an( 



I nerves. It is lined by 



Fig. 256. — Diagram of Sagittal Section of 

 Male Pki.vis to show Disposition of 

 Peritoneum. 



a. Pouch between rectum and roof of cavity, 

 continuous laterally with b, recto-genital pouch; 

 c, vesico-genital pouch; d, pouch below blatlder 

 and its lateral ligaments. The lateral line of re- 

 flection of the peritoneum is dotted. The area, 

 of rectum covered \)y iieritoneum varies widely. 

 ^^'hen the rectum is empty, the reflection dorsally 

 may be at the ijosterior end of the sacrum; when 

 the rectum is very full, the reflection may occur a 

 short distance behind the promontory. 



If the rectum be raised, it will be seen 



Fig. 257. — Schematic Cross-sections to show Arrangement of Pelvic Peritoneum of Horse: A, in Male; 



B, IN Fem.\le. 

 A: a, b. Recto-genital pouch; c, c, vesieo-genital pouch; d, d, pouch below bladder and its lateral ligaments; 

 1, mesorectum; 2, 2, urogenital fold; S, 3, lateral, 4, median ligaments of bladder; v. d., vas deferens; u m., uterus 

 masculinus. B: a, b, recto-genital pouch; c, c, vesico-genital pouch; d, d, pouch below bladder and its lateral 

 ligaments; i, mesorectum; ^, ;2, broad ligaments of uterus; 3, 3, lateral, 4, median ligaments of bladder. 



that the peritoneum passes from its ventral surface and forms a transverse fold 

 which lies on the dorsal surface of the bladder (Fig. 272). This is the urogenital 



