THE PELVIC CAVITY 



355 



organs, some foetal remnants, muscles, vessels, and nerves 

 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 genei'al 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 part of that tube. 

 Laterally it is reflected in a similar fashion. 



It is lined by 



Fig. 250. — Diagram of Sagittal Section of 

 Male Pelvis to show Disposition op 

 Peritoneum. 



a. Pouch between rectum and roof of cavity, 

 continuous laterally with b, recto-genital jjouch; 

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

 and its lateral ligaments. The lateral line of re- 

 flection of the peritoneum is doited. The area 

 of rectum covered by peritoneum varies widely. 

 When the rectum is empty, the reflection dorsally 

 may be at the posterior 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 Arr.angement of Pelvic Peritoneum of Horse: A, in Male; 



B, in Female. 

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

 1, mesorectum; 2, 2, urogenital fold; 3, 3, lateral, Jt, 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; 1, mesorectum; 2, 2, broad ligaments of uterus; 3, 3, lateral, 4. median ligaments of bladder. 



that the peritoneinn 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 



