240 THE DIGESTIVE SYSTEM 



portal vein and bile-duct in Fig. 90 have disappeared in 

 Fig. 91, so that these structures become much more intim- 

 ately related to one another. 



The jejunum and ileum are suspended within the peritoneal 

 cavity by the mesentery. This fold possesses an oblique 

 attachment to the posterior abdominal wall, extending from 

 the left side of the second lumbar vertebra, downwards and 

 to the right, into the right iliac fossa, and it permits a wide 

 range of movement to the gut. The blood-vessels, nerves and 

 lymph vessels pass to and from the intestine between its two 

 layers, and the mesenteric lymph glands occupy a similar posi- 

 tion. When the glands are enlarged and tuberculous, they 

 throw definite shadows in radiograms, and they can be recog-. 

 nised by the irregularity of their disposition and by the fact 

 that their distribution is quite different in radiograms taken at 

 different times. 



The peritoneal cavity shows a natural subdivision into 

 smaller parts. The supra-colic compartment lies above and 

 in front of the greater omentum, the stomach, the lesser 

 omentum and the liver (Fig. 88), and it communicates with 

 the omental bursa (lesser sac). The infra-colic compartment 

 lies below and behind the greater omentum, the transverse 

 colon and the transverse mesocolon, and it is further sub- 

 divided into right and left parts by the mesentery. The 

 pelvis constitutes the lowest compartment of the peritoneal 

 cavity. These compartments are not completely separated 

 from one another, but inflammatory conditions tend, as 

 a rule, to be localised to the compartment in which they 

 originate. 



The peritoneum is a large lymph-sac and it contains lymph 

 which normally transudes from the abdominal blood-vessels. 

 The parietal peritoneum possesses stomata, which serve to 

 drain away the lymph, and these stomata are most numerous 

 on the inferior aspect of the diaphragm. In cases of peri- 

 tonitis, it is important therefore to prevent septic material 

 from reaching the inferior aspect of the diaphragm, and this 



