Page 17 - My FlipBook

PART THE FIRST.

THE NATURAL HISTORY OF THE HUMAN
TEETH.

OF THE UPPER JAW.
Befoee we enter into a description of the Teeth themselves,
it will be necessary to give an account of the Upper and Lower
insisting minutely on
Jaw-bones, in which they are inserted ;
those parts which are connected with the Teeth, or serve for
their motion and action, and passing over the others slightly.
The Upper-Jaw is composed of two bones, (a) which generally

(a) [The superior maxillary bones (maxillae super lores). In addition,
it may be stated that the palatine bone on each side is generally
reckoned as constituting part of the upper jaw, although in the cavity
of the mouth it is confined to the palate, and forms no portion of the
alveolar process. In the class Mammalia, the upper jaw consists of three
bones on each side,—the palatine, superior maxillary, and inter- or pre-
maxillary bones. The last-named bones constitute the anterior portion
of the jaw, and form the alveoli of the superior incisors. Whatever
modification in size or shape the teeth implanted in the premaxillary
bones may display, they are, nevertheless, classed as incisors in the
dental formulae of naturalists. Anchylosis between the superior and
premaxillaries takes place sooner or later in life in the typical Quadru-
niana. In the Chimpanzee, the facial portion of the maxillc-inter-
maxillary suture disappears at or about the period of the first dentition ;
in the Orangs, the suture remains until the development of the great
canine teeth ; in the Semnopitheci and Inui, the separation continues
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