The =stomach= is large and pyriform. Its average capacity is about 1½ to
2 gallons (ca. 5.7 to 8 liters). When full it extends backward to the
last left intercostal space laterally and the umbilicus ventrally. The
left portion is large and rounded, while the right portion (Pars
pylorica) is small, and bends sharply upward to join the small
intestine. The parietal surface is related to the liver, gall-bladder,
and diaphragm. The visceral surface is related to the intestine, the
mesentery, and the pancreas. The great curvature is related to the
diaphragm, spleen, and abdominal floor. The pyloric end lies on the
right lateral lobe of the liver. The left extremity presents a flattened
conical blind pouch, the =diverticulum ventriculi=, the apex of which
projects backward. The œsophagus joins the stomach very obliquely,
almost in the median plane, and about three or four inches (ca. 8 to 10
cm.) below the twelfth thoracic vertebra. The cardiac opening is
slit-like and is bounded above and to the left by a fold which contains
a thickening of the internal oblique layer of the muscular coat. The
opening into the diverticulum is situated above and a little to the left
of the cardia; it is transversely oval, and is bounded (except
externally) by a thick fold which contains spirally arranged muscular
fibers. The mucous membrane may be divided into four regions. Over a
quadrilateral area around the cardia (about one inch on the right and
two or three inches on the left side of the orifice) it is œsophageal in
character, and presents a number of folds. A sharp line of demarcation
separates this from the rest of the mucous membrane, which is soft and
glandular. The second or cardiac gland region is pale gray in color and
thin (ca. 0.5 to 1 mm.); it extends about to the middle of the stomach.
The third or fundus gland region is readily distinguished by its
thickness (ca. 3 mm.) and its brownish-red mottled appearance.[113] The
fourth or pyloric region is pale, thinner than the preceding, and
presents a number of irregular folds. At the pylorus there is a
remarkable ridge which projects from the wall of the lesser curvature
and diminishes considerably the size of the orifice. It is about an inch
and a half (ca. 3 to 4 cm.) long and nearly half an inch (ca. 1 cm.)
high. Sometimes it is grooved; in other cases it has the form of a
rounded eminence attached by a pedicle to the wall. Fibers from the
circular muscular coat extend into it.
[Illustration:
FIG. 321.—LIVER OF PIG, SOFT SPECIMEN SKETCHED WITH LOBES DRAWN APART.
]