Section II. THE SUPRAGASTRIC STRUCTURES
The oral complex consists of the structures commonly known together as the
mouth. It takes in and initially processes food items. See figure 1-2.
Figure 1-2. Anatomy of the oral complex.
(1) A tooth (figure 1-3) has two main parts, the crown and the root. The 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. These are eventually replaced by a permanent
set of 32.
DECIDUOUS = to be shed