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BONES. 81
The Superior Border is the thickest of the four, iind is shaped like
the letter V. The upper portion of this V is described as two alse or
wings, which extend on both sides of the rostrum of the sphenoid bone.
The latei'al edge of each wing articulates Avith the superior margin of
the internal plate of the pterygoid process (vaginal process) of the sphe-
noid bone and the sphenoidal process of the palate bone.
The Inferior Border is long, thick, and uneven, for articulation with
the nasal crest of the superior maxillary and palate bones. It is thin-
ner posteriorly where it articulates with the latter bones.
The Anterior Border slopes downward and forward at an angle of
about forty-five degrees. The upper half of this border generally con-
sists of two thin laminse of bone, between which articulates the perpen-
dicular plate of the ethmoid. The inferior half is rough and uneven,
to give attachment in the recent state to the nasal cartilage.
The Posterior Border is free, and forms the septum of the posterior
nares. It is the shortest of the four borders—thin, smooth, and slightly
concave.
Tlie Surfaces.—The right and left surfaces are smooth, but marked
by narrow grooves for the accommodation of blood-vessels. A larger
groove, sometimes formed into a canal (naso-palatine), traverses each
surface of this bone, running downward and forward, terminating in
the anterior palatine canal in the intermaxillary suture. These grooves
transmit the naso-palatine vessels and nerves.
Development.—The vomer is an intracartilaginous bone formed
from one centre of ossification, which makes its appearance in the poste-
rior part of the bone at about the eiglith week of embryonic life. From
this centre two laminae arise, and pass upward and forward on each side
of the median line until they meet the nasal cartilage. These two plates
of bone gradually unite from behind forward until about the age of
puberty, at which period they form a single plate of bone, marked on
its anterior and superior borders by a slight groove, indicating the
position where the two parts unite.

Superior Maxillary Bones.
The superior maxillary bones are of the utmost importance to the
dentist and to the surgeon. They give support to the upper teeth and
are subject to defects of development and to various pathological changes.
Chief among these may be mentioned cleft palate, congenital or acquired,
necrosis, caries, and odontocele. Either of these bones may be affected
by alveolar abscess, diseases of the antrum, which may give rise to such
symptoms as impaired respiration and discharge of offensive matter
through the nasal chamber. Tumors or abscesses of the antrum often
grow to such a size as to elevate the floor of the orbit, depress the roof
of the mouth, and bulge out the wall of the cavity, distorting the face
in the region of the canine fossa. Neuralgic trouble in the teeth may
be only symptomatic of disease of this bone, as neuralgia in the head
often may be traceable to the teeth. It is therefore highly necessary
that the bone should be carefully studied.
Together, the superior maxillae are, of the bones of the face, second in
Vol. 1.-6