The oral complex consists of the structures commonly known together as the
mouth. It takes in and initially processes food items. See figure 6-2.
a. Teeth.
(1) A tooth (figure 6-3) has two main parts--the crown and the root. A
root canal passes up through the central part of the tooth. The root is suspended within a
socket (called the alveolus) of one of the jaws of the mouth. The crown extends up above
the surface of the jaw. The root and inner part of the crown are made of a substance
called dentin. The outer portion of the crown is covered with a substance known as enamel.
Enamel is the hardest substance of the human body. The nerves and blood vessels of the
tooth pass up into the root canal from the jaw substance.
(2) There are two kinds of teeth-- anterior and posterior. The anterior
teeth are also known as incisors and canine teeth. The anterior teeth serve as choppers.
They chop off mouth-size bites of food items. The posterior teeth are called molars. They
are grinders. They increase the surface area of food materials by breaking them into
smaller and smaller particles.
(3) Humans have two sets of teeth--deciduous and permanent. Initially, the
deciduous set includes 20 baby teeth.
DECIDUOUS = to be shed
These are eventually replaced by a permanent set of 32.
b. Jaws. There are two jaws--the upper and the lower. The upper is
called the maxilla. The lower is called the mandible.
(1) In each jaw, there are sockets for the teeth. These sockets are known
as alveoli. The bony parts of the jaws holding the teeth are known as alveolar ridges.
(2) The upper jaw is fixed to the base of the cranium. The lower jaw is
movable. There is a special articulation (T-MJ--temporo-mandibular joint) with muscles to
bring the upper and lower teeth together to perform their functions.
c. Palate. The palate serves as the roof of the mouth and the floor
of the nasal chamber above. Since the anterior two-thirds is bony, it is called the hard
palate. The posterior one-third is musculo-membranous and is called the soft palate. The
soft palate serves as a trap door to close off the upper respiratory passageway during
swallowing.
d. Lips and Cheeks. The oral cavity is closed by a fleshy structure
around the opening. Forming the opening are the lips. On the sides are the cheeks.
e. Tongue. The tongue is a muscular organ. The tongue is capable of
internal movement to shape its body. It is moved as a whole by muscles outside the tongue.
Interaction between the tongue and cheeks keeps the food between the molar teeth during
the chewing process. When the food is properly processed, the tongue also initiates the
swallowing process.
f. Salivary Glands. Digestion is a chemical process which takes
place at the wet surfaces of food materials. The chewing process has greatly increased the
surface area available. The surfaces are wetted by saliva produced by glands in the oral
cavity. Of these glands, three pairs are known as the salivary glands proper.
g. Taste Buds. Associated with the tongue and the back of the mouth
are special clumps of cells known as taste buds. These taste buds literally taste the
food. That is, they check its quality and acceptability.
Primary Content Providers: The U. S. Army, The
U.S. Navy
Ancillary Content and Online Version: David L. Heiserman
Publisher: SweetHaven Publishing Services
