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BONES. 103 ;
It is broader behind than in front, and is marked by sixteen pits of
various shapes for the accommodation of the teeth. The pits for the
central incisors are the smallest, conical in shape, and compressed later-
ally. Those for the lateral incisors are somewhat larger and not (piite
so compressed. The cavities for the cuspids (canine or stomach) teeth
are situated at the angles of this border, are larger and deeper than
those for the incisors, but less compressed in proportion to their size.
The six anterior sockets just described are arranged in the form of an arc,
while those for the remainder of the teeth extend in almost a straight
line posteriorly, the straightness of the line varying with the tempera-
ment of the individual. The sockets for the bicuspid teeth are variably
compressed and occasionally bifurcated, though it is exceptional to find
a double-rooted inferior Jbicuspid. The sockets for the molar teeth are
round superiorly, but as they descend soon bifurcate into two flattened
cone-shaped depressions. Those for the third molar or wisdom tooth,
however, vary from this rule just as their roots vary.
The Alveolar Proces.^ is very similar to that of the superior maxilla
before described, the principal point of difi'erence being in the external
plate. The external plate of the superior maxilla is thin throughout
the entire surface—so much so that the roots of the teeth are often bared
in macerating the bone. In the inferior maxilla the external plate is
thick and compact, thus rendering the lower teeth more difficult of
extraction than those in the upper jaw. After extraction the external plate
of the superior maxilla is absorbed much more rapidly and to a greater
extent than the internal plate, while with the external and internal plates
of the inferior maxilla the rate of absorption is more uniform.
The Inferior Border of the bone extends from a depression at the
union of the ramus with the body of the bone to the same point ujjon
the opposite side. It is thick, strong, rounding, and composed of com-
pact tissue. The depression or groove at the union of the ramus at the'
base of the bone is sometimes called " the facial notch." It is at this
point that the facial artery passes from the neck to the face—an import-
ant fact to remember when the parts are wounded or in surgical opera-
tions on the face, for hemorrhage can generally be controlled by pressure
at this point.
The Rami or Ascending Portions of the inferior maxilla arc quad-
rilateral in shape and divided into two surfaces, external and internal
fjur borders, superior, inferior, anterior, and posterior ; and two pro-
cesses, the condyloid and coronoid.
The External Surface is nearly flat. It is slightly roughened near
its posterior inferior angle for the insertion of the masseter muscle.
The Internal Surface.—The central portion is marked by an oblique
opening, the posterior or inferior dental foramen. Running downward
and forward from the lower border of this foramen is a groove, the
mylo-hyoid, already described. Posterior to this groove, extending to
the angle of the bone, is a roughened surface for the insertion of the
internal pterygoid muscle.
The Posterior or Inferior Dental Foramen is oval in shape; a sharp
border of bone extends along its anterior margin, and terminates above in
a spine for the insertion of the internal lateral ligament of the lower jaw.