in contained in saliva.

137. The Pharynx and OEsophagus. The dilated upper part of the
alimentary canal is called the pharynx. It forms a blind sac above
the level of the mouth. The mouth opens directly into the pharynx, and
just above it are two openings leading into the posterior passages of the
nose. There are also little openings, one on each side, from which begin
the Eustachian tubes, which lead upward to the ear cavities.

The windpipe opens downward from the pharynx, but this communication can
be shut off by a little plate or lid of cartilage, the epiglottis.
During the act of swallowing, this closes down over the entrance to the
windpipe, like a lid, and prevents the food from passing into the
air-passages. This tiny trap-door can be seen, by the aid of a mirror, if
we open the mouth wide and press down the back of the tongue with the
handle of a spoon (Figs. 46, 84, and 85).

Thus, there are six openings from the pharynx; the oesophagus being
the direct continuation from it to the stomach. If we open the mouth
before a mirror we see through the fauces the rear wall of the pharynx. In
its lining membrane is a large number of glands, the secretion from which
during a severe cold may be quite troublesome.

The oesophagus, or gullet, is a tube about nine inches long,
reaching from the throat to the stomach. It lies behind the windpipe,
pierces the diaphragm between the chest and abdomen, and opens into the
stomach. It has in its walls muscular fibers, which, by their worm-like
contractions, grasp the successive masses of food swallowed, and pass them
along downwards into the stomach.

138. Deglutition, or Swallowing. The food, having been well chewed
and mixed with saliva, is now ready to be swallowed as a soft, pasty mass.
The tongue gathers it up and forces it backwards between the pillars of
the fauces into the pharynx.

If we place the fingers on the "Adam's apple," and then pretend to
swallow something, we can feel the upper part of the windpipe and the
closing of its lid (epiglottis), so as to cover the entrance and prevent
the passage of food into the trachea.

There is only one pathway for the food to travel, and that is down the
oesophagus. The slow descent of the food may be seen if a horse or
dog be watched while swallowing. Even liquids do not fall or flow down the
food passage. Hence, acrobats can drink while standing on their heads, or
a horse with its mouth below the level of the oesophagus.