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92 ANAT03IY.
The Internal Border is much thicker than any of the others. It is
serrated and elevated into a ridge, which, when articulated with the
corresponding one of the opposite bone, forms a continuation of the
nasal crest of the superior maxilla, with which the vomer articulates.
The Vertical Plate is thin, and extends from the floor of the nasal
chamber to the upper extremity of the spheno-palatine notch. It has
two surfaces, an external and an internal ; and four borders, an anterior,
jDOsterior, superior, and inferior.
The Ldernal Surface is similar in structure to the same surface of
the superior maxilla. It is divided into three portions by two antero-
posterior ridges, the superior and inferior turbinated crests. The inferior
crest articulates with the inferior turbinated bone, and thus forms the
division between the inferior and middle meati of the nose. The
superior crest articulates with the middle turbinated bone (part of the
ethmoid), and forms the division between the middle and superior
meati of the nose. Between the superior turbinated crest and the
superior border of the bone is a groove which forms part of the superior
meatus.
The External Surface is generally rough and uneven. Its posterior
boundary is marked by a groove (occasionally a canal) M'hich, in the
articulated skull, forms the posterior palatine canal, already described.
The Anterior Border is thin, its inferior turbinated crest projecting
anteriorly to form the maxillary process. This process assists in closing
the maxillary sinus.
The Posterior Border (Fig. 40) is irregular and serrated. Its lower
third is marked internally by a deep groove, the edges of which articu-
late with the internal plate of the
Fig. 40.
pterygoid process of the s])henoid
t*' bone, a portion of which fits into
the groove. Above the groove
this border articulates with tlie
outer edge of the internal ptery-
goid plate, the thin projecting
border overlapping its internal
ShhcnoiJ-al /i roress. surface.
-Articu lur hort.
The Superior Border is divi-
iS on. uritcuui'r Aort ^
ded by a deep notch, sometimes
a foramen, the spheno-palatine
notch or foramen, which divides
the orbital from the sphenoidal
process.
The Spheno-palatine Notch or
Foramen is converted into a fora-
men by articulation with the sphe-
noid bone. It transmits the sphe-
no-palatine vessels and nerves
from the spheno-palatine fossa
Left Palate Boue, posterior view (enlarged).
into the nasal chambers.
The Inferior Border joins the external border of the horizontal plate.
The Pyramidal Process extends downward and backward from the