Page 23 - My FlipBook

OF THE ALVEOLAR PROCESSES. 7
its internal a little backward ; so that the axis of the two Con-
dyles are neither in the same straight line, nor parallel to each
other ; but the axis of each Condyle, if continued backwards,
would meet, and form an angle of about one hundred and forty-
six degrees ; and lines drawn from the Symphysis of the Chin,
to the middle of the Condyle, would intersect their longest
axis, at nearly right angles. There are, however, some excep-
tions ; for in a Lower-Jaw, of which I have a drawing, the
angle formed by the supposed continuation of the two axes,
instead of being an angle of one hundred and forty-six degrees,
is of one hundred and ten only. The Lower-Jaw serves for a
base to support the Teeth in the Alveolar Process, during their
action on those of the Upper-Jaw in mastication ; and to give
origin to some muscles that belong to other parts.
OF THE ALVEOLAR PROCESSES.
The Alveolar Processes are composed of two thin bony plates,
one external, and the other internal. These two plates are at a
greater distance from each other at their posterior ends, than at
the anterior, or middle part of the Jaw. They are united to-
gether by thin bony partitions going across, which divide the
processes at the anterior part, into just as many distinct sockets
as there are Teeth ; but at the posterior part, where the Teeth
have more than one root or fang, there are distinct cells, or
sockets, for every root. These transverse partitions are more
protuberant than the Alveolar Plates ; and thus add laterally to
the depth of the Cells, particularly at the anterior part of the
Jaw. At each partition, the external plate of the Alveolar
Process is depressed, and forming furrows, or a fluting rounds
the cells, or cavities, for the roots of the Teeth. This is ob-
servable in the whole length of the Alveolar Process of the
Upper-Jaw ; and in the fore-part particularly of the Lower-Jaw.
The Alveolar Process of each Jaw, form about one-half of a
circular, or rather of an elliptical figure ; (/) and at the fore-part

(/) [The elliptical figure described by the alveolar borders of both jaws,