b. The large intestine consists of three divisions: the cecum, the colon, and the
rectum. The cecum is the first two or three inches of this organ. The colon begins at
the open end of the cecum and is further divided into four parts: the ascending colon,
the transverse colon, the descending colon, and the sigmoid colon. The ascending
colon comes down on the right side of the abdomen, reaches the undersurface of the
liver, and turns abruptly to the left. As the large intestine continues across the abdomen
to the left side, it becomes the transverse colon. The intestine then curves beneath the
lower end of the spleen on the left side and is called the descending colon. The sigmoid
colon is the intestine continuing and projecting inward to the midline of the body and
ending as the rectum at about the level of the third sacral vertebra. The rectum is about
the last seven or eight inches of the large intestine. The last one inch of the rectum is
the anal canal. The opening of the anal canal is guarded by an internal sphincter of
smooth muscle and an eternal sphincter of skeletal muscle. The anal canal's opening to
the outside is called the anus, an opening usually closed except during the elimination
of the wastes of digestion.
SALIVARY GLANDS--ACCESSORY ORGANS
a. The salivary glands are accessory structures that lie outside the mouth.
These glands secrete the major portion of saliva, the fluid that keeps the membranes of
the mouth moist. Saliva glands empty the saliva into ducts that let their contents flow
into the mouth. Refer to figure 1-1 for general position of the salivary glands.
Figure 1-5. Salivary glands.
b. These glands appear in pairs in three locations. The largest pair of salivary
glands are the parotid glands which are located below each external ear. The
submandibular glands are each located toward the back under the mucous membrane
which covers the floor of the mouth under the tongue. The sublingual glands, the
smallest of the salivary glands, are located toward the front of the mouth from the