a. Secreting fluids into the oral cavity are such glandular structures as the
salivary glands and the buccal glands. (The buccal glands are serous and mucous
glands on the inner surfaces of the cheeks.) These fluids are collectively known as the
b. Saliva serves to wet the surface areas of the food particles produced by
mastication. In addition, saliva also dissolves some of the molecules of the food items.
c. Taste buds sample these dissolved molecules and test the quality of the food
being eaten. Taste buds are located on the tongue and the back of the oral cavity.
d. Another component of the saliva is mucus. The mucus tends to hold the food
particles together as a bolus. Since the mucus also makes this bolus somewhat
slippery, the bolus can slide readily through the initial portion of the digestive tract.
Section III. SWALLOWING (DEGLUTITION)
When the food has been adequately broken down (increased surface area),
wetted thoroughly, and tested (tasted), it is ready to be swallowed.
a. The bolus is moved posteriorly out of the mouth (oral cavity) into the pharynx
and then down through the esophagus to the stomach.
b. The pharynx is common to both the digestive and respiratory systems.
Therefore, as the bolus passes through the pharynx, both the upper and lower air
passageways must be protected. Otherwise, food particles might enter the
6-9. MOVEMENT OUT OF THE ORAL CAVITY
a. Initial Movement of the Bolus. There are intrinsic muscles in the tongue.
Through their action, the tongue arches upward and presses against the hard palate,
the roof of the mouth. This initiates the posterior movement of the bolus.
b. Action of the Hyoid Complex. The muscles of the hyoid bone pull the hyoid
bone upward and force the tongue upward into the oral cavity. This closes up the front
part of the oral cavity and forces the bolus further to the rear.
c. Action of the Soft Palate. As the bolus approaches the pharynx, the soft
palate is raised. Thus, the soft palate serves as a trap door to close the upper air