passageway. By tensing to resist the pressure from the bolus of food, the soft palate
ensures the continued backward movement of the bolus into the pharynx.
6-10. MOVEMENT THROUGH THE PHARYNX
a. Pharyngeal Constrictor Muscles. The wall of the pharynx contains three
pharyngeal constrictor muscles. By wavelike contractions, these muscles force the
bolus down into the beginning of the esophagus.
b. Action of the Epiglottis. As the hyoid bone's muscles raise the tongue up
into the oral cavity, they also raise the larynx. The larynx is raised because it is
attached to the inferior margin of the hyoid bone. As the larynx is raised, its epiglottis
automatically turns down over the opening of the larynx. Thus, food is prevented from
entering the lower-air passage-way.
6-11. MOVEMENT THROUGH THE ESOPHAGUS
The esophagus is a tube with muscular walls. It extends from the pharynx
above, through the neck and thorax, to the stomach in the abdomen. Wavelike
contractions (peristalsis) move the bolus through the esophagus to the stomach.
Section IV. TEMPORARY STORAGE
a. The stomach is a saclike enlargement of the digestive tract. By way of the
esophagus, the stomach receives the food that has been processed in the oral cavity.
b. The stomach's capacity is great enough to allow the individual to take in
enough food material at one time to last for an extended period of time. This allows the
individual to engage in activities other than eating.
c. In addition, certain digestive processes are initiated in the stomach.
d. The food is retained in the stomach for varying lengths of time, depending
upon the types of food eaten, the condition of the individual, and many other factors.
6-13. ADAPTATIONS OF THE STOMACH FOR THE STORAGE FUNCTION
The stomach is adapted as a storage area in several ways.
a. Its wall is quite stretchable. The mucosal lining of the stomach is thrown up
into longitudinal folds called rugae. These rugae flatten out as the stomach capacity