DISSECTION OF THE ABDOMEN. 313 



Peritoneal Pockets. The peritoneum, in passing from one organ 

 to another, forms several remarkable pockets, one of which has been 

 mentioned above in connection with the ligament of the ovary. The 

 exact position of the others will now be indicated. They possess 

 considerable interest, since a coil of intestine has been known to 

 become incarcerated in one or other of them. 



1. The entrance to the first of these pockets will be found imme- 

 diately in front of the base of the lobulus caudatus, which separates it 

 from the foramen of Winslow. It is bounded by the anterior end of the 

 right kidney, and by the lobulus caudatus and upper part of the right 

 lobe of the liver. It extends inwards to near the spine between the 

 diaphragm and the upper part of the right lobe of the liver. 



2. Another pocket will be found a little to the left of the root of the 

 anterior mesenteric artery, the entrance to it being on the anterior 

 surface of the mesentery suspending the first few inches of the jejunum. 

 The pocket is bounded in part by this piece of mesentery, and in part 

 by a peritoneal fold passing between the jejunum and the first part of 

 the single colon. 



3. Other two pockets will be found at the termination of the small 

 intestine. Turn the point of the caecum backwards and to the right, 

 and pull upon the terminal part of the jejunum. On each side of the 

 point at which the latter perforates the caecal crook there will be found 

 a recess, the posterior (in this position) being the deeper. 



4. Another considerable pocket will readily be found on the concave 

 side of the caecal crook, being formed by the peritoneum in passing 

 between the caecum and the beginning of the double colon. 



5. Another but much smaller pocket will be found in the cavity of 

 Winslow, above and in front of the first few inches of the single colon. 



Directions. — For the display of the mesenteric vessels and the sympa- 

 thetic nerve, the intestines should first be disposed after the manner of 

 Plate 41. When well injected the arteries require but little dissection, 

 and they are closely accompanied by the veins and nerves. The arteries 

 of the caecum and colon should be taken where most conspicuous, and 

 traced in both directions. Each of these vessels must be carefully dis- 

 sected up to its point of origin, but only two or three of the arteries of 

 the small intestine need be fully dissected. The whole intestinal tube, 

 with the exception of a short piece of the duodenum next the stomach, 

 is supplied by the anterior and posterior mesenteric arteries, which are 

 branches of the abdominal aorta. The first supplies the whole of 

 the small intestine except the piece of duodenum specified ; and it 

 also supplies the caecum, the large colon, and a few inches of the 

 beginning of the small colon. The remainder of the small colon and 

 the rectum are supplied by the posterior mesenteric artery. 



The Anterior Mesenteric Artery (Plate 41) comes off from the 



