1238 THE DIGESTIVE SYSTEM. 



by a fold passing from the cervix of the uterus around the sides of the pouch 

 towards the rectum ; these are the plicae rectouterinse [Douglasi] (O.T. folds of Douglas), 

 and they contain in their interior the musculi rectouterini (O.T. utero-sacral liga- 

 ments), two bands of fibrous tissue with plain muscle fibres intermixed, which 

 pass from the cervix of the uterus, backwards on each side of the rectum, to 

 blend with the connective tissue on the front of the lower part of the sacrum. 



Similarly, in front of the uterus, between it and the bladder, is found the much 

 smaller excavatio vesicouterina (utero-vesical pouch). Finally, the peritoneum 

 is prolonged as a wide fold from each margin of the uterus to the side wall of 

 the pelvis, constituting the ligamentum latum uteri (broad ligament of the uterus), 

 within which are contained the uterine tube, the ovary, the ligamentum teres, 

 and other structures (see pp. 1315 et seq.y. 



When the bladder is empty, there is seen at each side, between it and the pelvic wall, a con- 

 siderable peritoneal depression the paravesical fossa (Fig. 965). This fossa is traversed by a 

 peritoneal fold the plica vesicalis transversa which runs transversely laterally from the 

 superior surface of the empty bladder, and, when well marked, passes to the neighbourhood 

 of the abdominal inguinal ring. 



Above the bladder, on each side of the middle umbilical ligament, is found the internal 

 inguinal fovea already referred to (p. 1235). Both of these fossae are practically obliterated 

 by distension of the bladder. 



Similarly, there is seen at each side of the empty rectum, on the posterior pelvic wall, a large 

 depression, which may be known as the pararectal fossa (Fig. 965). When the rectum is empty 

 and contracted, these fossae are occupied by intestine ; during distension, the rectum, increasing 

 in width, expels the intestine and practically obliterates the fossae. 



Transverse Tracing of the Peritoneum. If the peritoneum is followed trans- 

 versely around the abdomen, just above the level of the iliac crest (Fig. 968), few 

 difficulties will be encountered. From the anterior abdominal wall it passes round 

 on each side to the back, lining the sides and the posterior wall. Passing medially 

 on the posterior wall, it meets the colon ascending on the right side, descending 

 on the left over which it is carried, in each case covering the bowel in front and 

 at the sides only, and leaving the posterior surface bare, as a rule. Sometimes, 

 however, the covering is complete, and a short mesentery is formed. It is next 

 continued medially over the psoas muscles, the ureters, and the great vessels, on 

 the front of which it meets the superior mesenteric artery and vein running 

 downwards to the intestines. From both sides it passes forwards on these vessels, 

 forming the right and left layers of the mesentery ; and finally, having reached 

 the intestine, it clothes it completely, and the two portions become continuous 

 on the bowel. 



A transverse tracing at a higher level would include the bursa omentalis ; it will, 

 therefore, be well to study this portion of the peritoneal cavity before describing 

 such a tracing. 



Bursa Omentalis (O.T. Lesser Sac of the Peritoneum). The omental bursa, as 

 already pointed out, is a diverticulum of the great sac. It lies behind the stomach 

 and adjacent organs, and communicates with the general cavity by a constricted 

 passage, called the foramen epiploicum [Winslowi]. If the general cavity is com- 

 pared, as already suggested, to a bag, the anterior layer of which clothes the 

 anterior wall and sides of the abdomen, and the posterior layer covers the viscera lying 

 on the posterior wall, the bursa omentalis would correspond to a pocket lying behind 

 the stomach, lesser omentum and part of the liver, and opening into its cavity by 

 a narrow mouth, on the right side, just below the liver. From this opening the 

 pocket passes to the left behind the lesser omentum and stomach, as far as the 

 spleen, up behind the caudate lobe of the liver, and down behind the stomach and 

 gastro-colic ligament. 



As in the case of the general peritoneal cavity, it will, of course, be understood 

 that the two walls of the bursa omentalis and the boundaries of the epiploic 

 foramen are normally in contact. We shall first consider this opening, and then 

 trace the layers of the omental bursa. 



Foramen Epiploicum (Winslowi) (Fig. 966). This, the constricted passage which 

 leads from the general peritoneal cavity into the bursa omentalis, is situated just 

 below and behind the porta hepatis. It is bounded anteriorly by the right, free 



