138 OSTEOLOGY. 
turbinalis), with which the hinder end of the superior border of the inferior 
turbinated bone articulates; above and below this it enters into the formation of 
the outer wall of the middle and inferior meatuses of the nose respectively. Near 
the upper extremity of the vertical plate, and below the processes which spring 
from it, there is another ridge more or less parallel to that already described. 
This is the superior turbinated or ethmoidal crest (crista ethmoidalis), and with this 
the hinder extremity of the middle turbinated bone is united. The eaternal surface, 
which forms the inner wall of the spheno-maxillary fossa, is channelled by a 
vertical groove (sulcus pterygo-palatinus), converted into a canal by articulation 
with the superior maxillary bone. This canal, called the posterior palatine canal, 
transmits the large palatine nerve and descending palatine vessels. Anteriorly 
the external surface projects forwards to a variable extent, and helps to close in 
the antrum of the maxilla by its maxillary process. The anterior border is a thin 
edge of irregular outline which articulates above with the ethmoid and below with 
the superior maxilla. The posterior border, thin above, where it articulates with 
the fore part of the internal pterygoid plate, expands below into a pyramidal 
process called the tuberosity. The inferior border of the vertical plate is confluent 
with the outer edge of the horizontal plate; posteriorly, and immediately in front 
of the tuberosity, it is notched by the lower extremity of the posterior palatine 
canal. The superior border supports the orbital and sphenoidal processes; the 
former—the anterior—is separated from the latter by a notch (incisura spheno- 
palatina), which is converted into the spheno-palatine foramen by the articulation of 
the palate bone with the under surface of the sphenoid. Through this communica- 
tion between the spheno-maxillary and nasal fossee pass the spheno-palatine artery 
and the nasal branches of the spheno-palatine ganglion. 
The tuberosity (processus pyramidalis) is directed backwards and outwards 
from the angle formed by the vertical and horizontal plates, and presents on its 
posterior surface a central smooth vertical groove, bounded on either side by rough 
articular furrows which unite above in a V-shaped manner with the upper thin 
posterior edge. These articulate with the fore parts of the lower portions of the 
internal and external pterygoid plates, the central groove which fits into the wedge- 
like interval between the two pterygoid plates thus entering into the formation of 
the pterygoid fossa. The outer surface of the tuberosity is rough above, where it 
is confluent with the outer surface of the vertical plate which articulates with the 
tuberosity of the superior maxilla; below, there is a small smooth triangular area 
which appears between the tuberosity of the superior maxilla and the outer surface 
of the external pterygoid plate, and so enters into the floor of the zygomatic fossa. 
Passing through the tuberosity in a vertical direction are the posterior and external 
accessory palatine canals (foramina palatina minora) for the transmission of the 
smaller palatine nerves and vessels. 
The orbital process (processus orbitalis), shaped like a hollow cube, surmounts 
the fore part of the vertical plate. The open mouth of the cube is directed back- 
wards and inwards towards the fore part of the body of the sphenoid, with the 
cavity of which it usually communicates ; the fore part of the cube articulates with 
the inner end of the angle formed by the orbital plate and zygomatic surface of 
the superior maxilla. Of the remaining four surfaces, one directed forwards and 
inwards articulates with the ethmoid. The others are non-articular: the swperior 
enters into the formation of the floor of the orbit; the eaternal is directed towards 
the spheno-maxillary fossa; whilst the inferzor, which is confluent with the inner 
surface of the vertical plate, is of variable extent, and overhangs the superior 
meatus of the nose. 
The sphenoidal process (processus sphenoidalis), much smaller than the orbital, 
curves upwards, inwards, and backwards from the hinder part of the summit of the 
vertical plate. Its superior surface, which is grooved, articulates with the fore part 
of the under surface of the body of the sphenoid and the root of the internal 
pterygoid plate, thereby converting the groove into the pterygo-palatine canal, which 
transmits an artery of the same name together with a pharyngeal branch from the 
spheno-palatine ganglion. Its outer side enters into the formation of part of the 
inner wall of the spheno-maxillary fossa. Its internal curved aspect is directed 
