246 PRACTICAL ANATOMY. 



SHORT SUMMARY OF PERITONEAL CONSIDERATIONS. 



1. The complex adult alimentary canal and its complex peritoneal invest- 

 ing membrane are evolved from a simple straight gut and a simple straight mes- 

 entery. 



2. The abdominal part of this canal in the foetus extends from the diaphragm 

 to the anus on the posterior wall of the abdominal cavity in front of the vertebral 

 column. It is attached to the anterior wall, as far downward as the umbilicus, 

 under the name of ventral mesentery. 



3. The stomach appears as an enlargement in the canal, and its dorsal mesen- 

 tery is called meso-gaster. 



4. The upper part grows much more rapidly than the lower, receiving a more 

 liberal blood-supply. In round numbers, the small intestine is the product of the 

 superior mesenteric artery ; the large intestine is the product of the inferior. 



5. At an early period the liver is in front of the stomach and the pancreas 

 behind. The liver grows into the ventral mesentery, the pancreas into the pos- 

 terior meso-gastrium. The primary mesentery of the pancreas fuses with the 

 posterior body wall. 



6. As the liver and spleen become larger, and as the bowel begins to rotate 

 about the superior mesenteric artery, the stomach assumes a transverse position, 

 the anterior border becomes the lesser curve, posterior border becomes the 

 greater curve, the left surface becomes the anterior, and the right surface becomes 

 the posterior. 



7. The small intestine rotates from left to right in such away that the large 

 intestine extends from right to left and crosses the small intestine near the 

 stomach. 



8. Rotation accounts for the duodenum passing under the second or trans- 

 verse stage of the colon and apparently through its transverse meso-colon. 



9. The meso-gaster becomes the greater omentum, consists of four layers, 

 grows out from the greater curvature of the stomach. 



10. The duodenum and ascending and descending colon lose their mesen- 

 teries. 



ABDOMINAL CONTENTS. 



Cut slightly to the left of the umbilicus, then through the linea alba to the 

 ensiform cartilage. It may be necessary to divide the cartilages of the two or 

 three lower true ribs to make ample room. Make the following observations 

 before any further dissecting is done : 



1. Find the broad ligament of the liver in the longitudinal fissure of this 

 organ. See the round ligament of the liver in the free margin of the broad. 

 This is the remains of the umbilical vein that brought aerated blood from the 

 placenta during intrauterine life. 



2. Locate the stonmcli, liver, spleen, and transverse colon. Lift the lower 

 margin of the liver upward, and at the same time pull the stomach downward ; 

 now see the peritoneal connection between the liver and stomach the gastro- 

 liepatic oincntnni or lesser omentum. Notice the peritoneal connection between 

 the stomach and the colon. This is the gastro-colic amentum or great amentum. 

 See the peritoneal connection between the left end of the stomach and the spleen. 

 This is the gastro-splenic omentum. Folds of peritoneum that connect organ to 

 organ are called omenta, and the three above given are the omenta. 



