Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/87

Rh Open the abdominal cavity by a median incision from the diaphragm to the pelvis.

The stomach lies on the left side in the abdominal cavity, in contact with the concave posterior side of the liver. It resembles a half of a doughnut in shape. The long axis forms approximately a right angle with the long axis of the body. The greater curvature which corresponds to the outer edge of the doughnut, is ventral. The lesser curvature, analogous to the rim of the doughnut's hole, is dorsal. The esophagus enters the stomach on its dorsal side, through the cardiac orifice, or cardia, near the center of the lesser curvature. The esophagus is closer to the right half of the lesser curvature than to the left, thus entering the stomach obliquely. External inspection of a full stomach reveals two distinct regions. The wall of somewhat more than the left half, the cardiac sac, is flexible, thin, and in a preserved specimen sufficiently transparent to permit the food it contains to be seen from the outside. The wall of the right region of the stomach, on the other hand, is opaque and relatively firm. This part decreases in size dorsally and communicates with the small intestine through the pylorus. The inner surface of the stomach comprises two areas corresponding to the two regions seen from the outside. These may be seen to good advantage by opening the distended organ with an incision extending throughout the length of the greater curvature. The inner surface of the cardiac sac at the left is hard, smooth, and glossy. The wall is tough. If the stomach was distended with food when the animal died, the wall is slightly transparent, the transparency increasing as the tissue dries. In the region at the right the inner surface is yellowish in color, opaque, brittle in a preserved animal, and more or less prominently folded, especially near the pylorus and on the greater curvature. The two re