DIGESTIVE SYSTEM OF THE DOG—THE MOUTH 491 
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 
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 em.) and a width of 3 to 4 inches (ca. 8 
to 10 em.), 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 
Fic. 482.—SpieEn oF Pic; ViscERAL 
SURFACE. 
1, Dorsal end; 2, ventral end; 3, 
stumps of splenic vessels; 4, gastric 
surface; 5, hilus with vessels. 
large adult it may be only a little more than a foot (ca. 35 em.) long, two and a half inches wide, 
and weigh six or seven ounces (ca. 200 gm.). 
DIGESTIVE SYSTEM OF THE DOG 
THE MOUTH 
The size and form of the mouth vary greatly in different breeds, the cavity 
being 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 
