310 ABDOMEN 



lobe of the liver occupies the right vault of the diaphragm, 

 whilst the left lobe of the liver, the fundus of the stomach, 

 and the spleen occupy the left vault. The base of the right 

 lung is in relation to the right lobe of the liver. The 

 pericardium, in by far the greater part of its extent, lies 

 above the left lobe of the liver, which therefore intervenes 

 between it and the stomach ; only a limited portion of the 

 apex of the heart, which is inside the pericardium, extends 

 over the region of the stomach. The base of the left lung 

 lies over the left lobe of the liver, the fundus of the stomach, 

 and the spleen. 



Intestinum Tenue. The small intestine is that part of 

 the alimentary canal which succeeds the stomach. It begins, 

 in the epigastric region, at the pylorus, and ends, in the upper 

 part of the right iliac region, by joining the large intestine. 

 Its average length is somewhere about seven metres (twenty- 

 three feet). It diminishes slightly in calibre from its 

 commencement to its termination, and it is divided into three 

 portions, viz. : 



1. The duodenum. 



2. The jejunum. 



3. The ileum. 



The duodenum is the name which is given to the first 

 part of the small intestine. It is about 25 cm. (ten inches) 

 long, and it extends, in a horse-shoe-shaped curve, from the 

 pylorus to the left side of the body of the second lumbar 

 vertebra. As it lies deeply in the greater part of its extent, 

 and as further dissection is necessary to display its relations, 

 it is not convenient to consider it at present. 



The jejunum and ileum constitute the coils of the small 

 intestine, which, under ordinary circumstances, are more or 

 less completely covered in front by the greater omentum. 

 The jejunum begins where the duodenum ends, viz. at the 

 left side of the body of the second lumbar vertebra ; and 

 the ileum ends in the upper part of the right iliac region by 

 joining the large intestine at the upper end of the caecum. 

 The subdivision of the small intestine is of the most arbitrary 

 kind. It is customary for anatomists to look upon the upper 

 two -fifths of the small intestine beyond the duodenum as 

 being jejunum, and the lower three-fifths as being ileum. 

 There is no hard-and-fast line of demarcation between those 

 two divisions the one passes insensibly into the other; 



