ABDOMINAL VISCERA OF THE HORSE. 681 
As to the shape of the duodenum, from the pylorus to the 
right of the porta we find its dimensions so very great as to 
have suggested to the ancients the similitude between it and 
the stomach, of which they regarded it in some degree as an 
analogue, as testified by the appellation “ Ventriculus Succen- 
turiatus” given to it by them. Further from the pylorus we 
find it constricts and assumes a certain caliber, which it main- 
tains till it loses its name for that of jejunum. 
With reference to the relations of the duodenum, it may be 
stated that they admit of detail on account of the fixedness of 
that portion of the gut, an attribute with which it is endowed in 
contradistinction to the jejunum and ileum. In the first portion 
of its course, i. e., from the pylorus to the posterior part of the 
right lobe of the liver, the duodenum by its upper surface is in 
contact with the concave surface of the latter organ crossing 
the vena portae, near which it is pierced by the biliary and 
pancreatic ducts, which enter it at about five or six inches from 
the pylorus, forming an acute angle with each other. The in- 
ferior surface of the duodenum rests on the transverse colon, and 
its superior margin is in close contact with the anterior part of 
the head of the pancreas. 
Round to the right, the duodenum is in contact with the 
hepatic flexure of the colon, right and Spigalian lobes of the 
liver, as well as the right kidney. To reach the spine it has to 
cross the direction of the right flexure of the colon, getting 
behind the mesentery and gastric flexure of the colon, where 
it is connected with the left kidney. 
Alluding next to the general anatomical facts as applied to 
the jejunum, so called on account of its usual vacuity after 
death, the limit between it and the ileum is defined by imagin- 
ing the small intestine, with the exception of the duodenum, 
divided into five equal portions, of which the first two take the 
name of jejunum, whilst the last three-fifths receive that of 
ileum. 
The jejunum is suspended superiorly from the spine by an 
extensive fold of peritoneum, termed mesentery, which serves 
also as a medium for the passage of the mesenteric arteries, 
veins and nerves, as well as for chyliferous vessels, to take 
their course towards the receptaculum chyli, situated to the 
left of the aorta. 
The width of the jejunum is far from being uniform, it being 
more constricted at some points than at others : its narrowest 
part is that which is contiguous to the ileum. 
The ileum is the terminating portion of the small intestine, so 
called from the tortuous course it takes, emptying itself into the 
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