The middle or muscular coat.
_7_. The interior or mucous coat. _10_. The beginning
of the duodenum. _11_. The pyloric orifice.]

The _Stomach_ is a musculo-membranous, conoidal sac, communicating with
the esophagus by means of the cardiac orifice (see Fig. 28). It is
situated obliquely with reference to the body, its base lying at the
left side, while the apex is directed toward the right side. The stomach
is between the liver and spleen, subjacent to the diaphragm, and
communicates with the intestinal canal by the pyloric orifice. It has
three coats. The peritoneal, or external coat is composed of compact,
cellular tissue, woven into a thin, serous membrane, and assists in
keeping the stomach in place. The middle coat is formed of three layers
of muscular fibers: in the first, the fibres run longitudinally; in the
second, in a circular direction; and in the third, they are placed
obliquely to the others. The interior, or mucous coat, lines this organ.
The stomach has a soft, spongy appearance, and, when not distended, lies
in folds. During life, it is ordinarily of a pinkish color. It is
provided with numerous small glands, which secrete the gastric fluid
necessary for the digestion of food. The lining membrane, when divested
of mucus, has a wrinkled appearance. The arteries, veins, and
lymphatics, of the stomach are numerous.

[Illustration: Fig. 29.
Small and large intestines. _1, 1, 2, 2_.
Small intestine. _3_. Its termination in the
large intestine. _4_. Appendix vermiformis.
_5_. Caecum. _6_. Ascending colon.
_7_. Transverse colon. _8_. Descending colon.
_9_. Sigmoid flexure of colon. _10_. Rectum.]

The _Intestines_ are those convoluted portions of the alimentary canal
into which the food is received after being partially digested, and in
which the separation and absorption of the nutritive materials and the
removal of the residue take place. The coats of the intestines are
analogous to those of the stomach, and are, in fact, only extensions of
them. For convenience of description, the intestines may be divided into
the _small_ and the _large_. The small intestine is from twenty to
twenty-five feet in length, and consists of the Duodenum, Jejunum, and
Ileum. The _Duodenum_, so called because its length is equal to the
breadth of twelve fingers, is the first division of the small intestine.
If the mucous membrane of the duodenum be examined, it will be found
thrown into numerous folds, which are called _valvu