Introduction

A. The teeth are arranged in upper and lower arches. Those teeth in the upper arch are termed maxillary, because they are set in the upper jaw, which is the maxilla (Plural - maxillae). The teeth in the lower arch are termed mandibular, because they are located in the lower jaw, which is the mandible. The mandible is the movable member of the two jaws, while the maxilla is stationary.

B. The imaginary vertical line which divides each arch, as well as the body, into two approximately equal halves, is the midline. Strictly speaking, this vertical division is not a one-dimensional line at all, but rather a two-dimensional plane, termed the mid-sagittal plane. However, since most dental authors persist in using the less appropriate term "midline", for consistency this text will also use it. The two approximately equal portions of each arch divided by the midline are termed quadrants. since there are four in the entire mouth. They are termed:

C. It is important to point out that as one looks directly at the oral cavity (or the body) from the front, the anatomical directions of right and left are reversed. Hence, the right side of the mouth is actually to the left of the viewer, while the left side of the mouth is to the right of the viewer.

D. The manner in which the mandibular teeth contact the maxillary teeth is called occlusion. The term for the process of biting or chewing of food is mastication.

maxillary (upper) right, maxillary (upper) left, mandibular (lower) right, mandibular (lower) left.

midline

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