DIGESTIVE SYSTEM OF THE DOG THE MOUTH 



491 



^m/ 



THE PANCREAS 

 The pancreas extends across the dorsal wall of the abdominal cavity behind 

 the stomach. It is triradiate or triangular. The right extremity is attached to the 

 first curve (Flexura portalis) of the duodenum, and here the duct passes to the 

 bowel. The left extremity is related to the left extremity of the stomach, the 

 dorsal end of the spleen, and the anterior pole of the 

 left kidney. The middle or posterior extremity or i 



lobe is practically median and is related to the portal 

 vein and the root of the mesentery. The pancreatic 

 duct passes from the right extremity directly through 

 the duodenal wall, opening about four or five inches 

 (ca. 10-12 cm.) from the pylorus. The interlobular 

 tissue usually contains a good deal of fat. 



THE SPLEEN 



The spleen is long and narrow. Its long axis is 

 nearly dorso-ventral in direction, and is curved to con- 

 form to the left part of the greater curvature of the 

 stomach. The dorsal end lies under the vertebral 

 ends of the last three ribs; it is related to the 

 stomach in front, the left kidney behind, and the 

 left extremity of the pancreas medially. The visceral 

 surface has a longitudinal ridge on which the hilus is 

 situated; this divides the surface into nearly equal 

 gastric and intestinal areas, which are in contact with 

 the stomach and colon respectively. The parietal 

 surface is convex and is related to the left lateral and 

 ventral wall of the abdomen. The ventral end is 

 smaller than the dorsal one; it lies on the abdom- 

 inal floor, usually in the umbilical region. The spleen 

 is attached so loosely to the stomach that it may be 

 regarded as being intercalated in the great omentum. 

 In large subjects it may reach a length of about 25 

 inches (ca. 60 cm.) and a width of 3 to 4 inches (ca. 8 

 to 10 cm.), and a weight of 10-15 ounces (ca. 350 gm.). 



The position of the spleen varies according to the fulness 

 of the stomach and its own size. The dorsal end varies little. 

 But the ventral end has a wide range, as might be expected; it 

 may be in contact with the left lobe of the liver or may be cen- 

 trally situated just in front of the umbilicus. As in other ani- 

 mals, the size of the spleen is extremely variable. Even in a 



large adult it may be only a little more than a foot (ca. 35 cm.) long, two and a half inches wide, 

 and weigh six or seven ounces (ca. 200 gm.). 



Fig. 432, — Spleen of Pig ; Visceral 

 Surface. 

 1, Dorsal end; 2, ventral end; 3, 

 stumps of splenic vessels; 4, gastric 

 surface; 5, hilus "nuth vessels. 



DIGESTIVE SYSTEM OF THE DOG 



THE MOUTH 



The size and form of the mouth vary greatly in different breeds, the cavity 

 teing in some long and narrow, in others short and wide. The rima oris is very 

 extensive, so that the labial commissure is opposite the third or fourth cheek tooth. 

 The lips are thin and mobile, and present numerous tactile hairs. The upper lip 



