THE INTESTINAL CANAL. 



1009 



1. French authors give three portions, ending it at the superior mesenteric 



Is : superior horizontal, vertical, and inferior horizontal parts. 

 -. To this third part Henle, Krause, Quain, and others add a fourth oblique 

 part ascending from right to left. 



3. Luschka. His. and Braune describe an 

 annular form. 



4. Cruvielhier, Young, and Treves describe 

 a fourth portion 2 cm. long, coming forward at 

 the end of duodenum, by joining the duodeno- 

 jejunal junction. They are all described as dif- 

 ferent types, of which, according to Jonnesco, 1 

 there are three. 



1. Annular or circular type, infantile; 



V-*Jiped type, \ ^^ rare in infent 



3. V '-shaped type, J 



(Figs. 632 and 633). 



The typical annular form is always found in 

 the child up to about the age of seven (Fig. 

 631). 



The terminal point of this variety is strongly 

 fixed to the left side of the first lumbar vertebra 

 and is exactly on the same level as the begin- 

 ning of the duodenum, and hence is behind the stomach (Fig. 634). 



Between these points, the one fastened by tbe muscle of Treitz and the other 

 by the hepato-duodenal ligament, the duodenum describes a regular curve in front 

 of the vertebral column. This ring is filled and its margins overlapped by the 



FIG. 631. Annular duodenum. Infan- 

 tile type, from boy of three years. (Jon- 

 nesco.) 



Aorta 



Aorta 



Musclf of Treitz 



FIG. 632. Duodenum in U- (Jonnesco.) 



FIG. 633. Duodenum in V. (Jonnesco.) 



head of the pancreas, the neck of which is limited by the two extremities of the 

 ring. 



In the adult this type may be found, but the terminal point does not usually 

 attain the same level that the origin has ; it is pushed back more to the left as 

 though the developing neck of the pancreas had forced the duodenal ring to open 

 more widely for its lodgment. 



Course of the Adult Duodenum. Separated from the pylorus at the right of 

 the upper edge of the first lumbar vertebra there is usually at first a bottle-shaped 

 dilatation, the antrum duodeni. The direction of the first portion depends on the 

 condition and length of the stomach and position of the pylorus. With an empty 

 stomach the first part is nearly horizontal and transverse. With a distended 

 stomach, it is nearly antero-posterior : its distal end is stationary and its proxi- 

 1 '' Anat. topographique du duodenum," Jonnesco, Paris, 1889. 



