382 



THE DIGESTIVE APPARATUS IN MAMMALIA. 



the 



Fig. 180. 



THEORETICAL TRANSVERSE SECTION 

 OF THE ABDOMINAL CAVITY, TO 

 SHOW THE DISPOSITION OF THE 

 PERITONEUM. 



cavity, B that of the aorta, at the level of the great mesenteric artery : 

 peritoneal membrane, oo, covers the walls of the abdomen, and at the points 

 DD (not inserted, but intended to be placed within the cavity below, and on 

 each side of b, the aorta) is folded around the great mesenteric artery in such 



a manner as to form two layers, ff, which 

 come in contact by their adherent face, 

 reach the intestine, and then separate to 

 envelop it. We then see in this figure the 

 parietal layer of the peritoneum, cc, the 

 visceral layer, gg, and the two layers, ff, 

 which establish the continuity of the parie- 

 tal and visceral portions; the complete 

 sac formed by these is apparent, and it 

 could be rendered more so by the further 

 separation and development of the layers 

 ff ; so that there is no difficulty in under- 

 standing how the small intestine may be 

 at the same time in the interior of the 

 abdominal cavity, and outside the sac 

 formed by the serous membrane which 

 lines that cavity. 



This arrangement is common to all the 

 organs freely suspended in the abdomen. 

 The serous folds which suspend them, in 

 joining their peritoneal layer to that which 

 covers the parietes of the cavity, will be studied under the names of 

 ligaments, mesenteries, and omenta. Some organs — the kidneys, for example 

 — have no proper visceral layer, being comprised between the abdominal 

 wall and the external face of the parietal peritoneum, and are invested 

 with none of the duplicatures just mentioned. 



We will briefly study the duplicatures, ligaments, mesenteries, and 

 omenta that the peritoneum forms, starting from the umbilicus and passing 

 forwards and backwards (Fig. 181). 



On reaching the suprasternal region, the peritoneum forms a falciform 

 duplicature, extending from the umbilicus to the middle lobe of the liver, 

 and which is even prolonged between that lobe and the posterior face of the 

 diaphragm ; at the free border of this fold is a thickening which is regarded 

 as the remains of the obliterated umbilical vein. In becoming doubled over 

 the neighbouring organs, the diaphragmatic portion constitutes : 1, The 

 ligaments of the right and left lobes of the liver ; 2, The common ligament 

 of that gland, which surrounds the posterior vena cava : 3, The cardiac 

 ligament that envelops the termination of the oesophagus. Behind the 

 liver is found the hepato gastric ligament, which fixes the stomach in the 

 posterior fissure of the liver and is, to the right and backwards, attached to 

 the duodenum at the lower face of the right kidney ; it is then directed from 

 right to left, and becomes continuous with the parietal peritoneum of the 

 sublumbar region and the mesentery proper. 



The two lamiuEe of the hepato-gastric ligament separate at the lesser 

 curvature of the stomach to cover that viscus ; then join at its greater cur- 

 vature, and pass to the interior of the abdominal cavity. This fold receives 

 the name of the great or gastro-colic omentum ; it leaves the left tuberosity 

 of the ventriculus, which it suspends to the sublumbar region from the 

 whole extent of the great curvature ; to the right it goes beyond the pylorus, 



