THE PERITONEUM . 367 



The middle region is called the umbilical, having the umbilicus 

 on the anterior surface. Above that is the epigastric, and below it 

 is the hypogastric. At the sides of the epigastric region are the 

 right and left hypochondriac. At the sides of the umbilical region 

 are the right and left lumbar; and at the sides of the hypogastric 

 region are the right and left iliac, or inguinal. 



The abdominal viscera are the stomach, intestines, liver, spleen, 

 pancreas, kidneys, and adrenal bodies. The great vessels are at the 

 back. The sympathetic ganglia are at the sides of the vertebrae, 

 with the celiac and other plexuses situated on the large vessels. 



The kidneys are behind all of the other viscera, and the 

 ureters run down close to the posterior wall of the abdomen on their 

 way to the bladder. 



The receptaculum chyli, or beginning of the thoracic duct, is in 

 front of the second lumbar vertebra. The inferior vena cava lies on 

 the right side of the aorta. 



The principal organ in the epigastric region is the stomach; in 

 the right hypochondriac, the liver; in the left hypochondriac, the 

 spleen. The umbilical region is occupied mostly by small intestines. 

 The right and left kidneys are in the two lumbar regions, with the 

 ascending colon in front of the right, and the descending colon in 

 front of the left kidney. The cecum and appendix are in the right 

 inguinal region; the bladder, in the hypogastric. 



Each region contains portions of several viscera in addition to those named. 

 Scarcely any organ save the spleen and cecum can be said to belong to but one 

 region. 



The peritoneum is a closed sac of serous membrane like a 

 water-bag, which is placed between the abdominal wall and 

 abdominal viscera. It is practically in front of the viscera, and 

 tucked in around them at the sides. One side of the sac is closely 

 applied to the abdominal wall, and is called the parietal peritoneum, 

 while the other side is fitted to the viscera, and called the visceral 

 peritoneum. Normal peritoneum is perfectly transparent, and the 

 viscera are plainly seen through the visceral layer. The peritoneal 

 cavity contains a little serous fluid and nothing else. 



An incision in the abdominal wall, including the parietal per- 

 itoneum, opens the peritoneal cavity. An incision into one of the 

 organs involves also the visceral peritoneum, with these exceptions: 



