158 OSTEOLOGY. 
eroove are lodged the aforementioned vessels and nerves. The surface of the palate 
in front of the transverse suture is rough, pitted for the palatine glands, and pierced by 
numerous small vascular foramina; the part of the palate behind the suture, formed 
by the under surface of the horizontal plate of the palate bone, is much smoother. 
From this there rises, just posterior to the orifice of the posterior palatine canal, a 
thin sharp crest which curves inwards immediately in front of the posterior free 
edge; to this are attached some of the tendinous fibres of the tensor palati muscle. 
Pterygoid Processes.—Buttressed against the hinder extremities of the alveolar 
arch are the pterygoid processes of the sphenoid. If carefully examined, these 
will be seen not to lie in actual contact with the maxille, but to be separated from 
them by the triangular wedge-shaped tuberosities (proc. pyramidales) of the palate 
bones. It is these latter which are pierced by the posterior and external accessory 
palatine canals (foramina palatina minora) which le just behind the posterior pala- 
tine canal, and through which pass the lesser palatine nerves. As here displayed, 
the pterygoid processes (processus pterygoidei) of the sphenoid he on either side of 
the opening of the posterior nares ; each consists of two plates, an internal (lamina 
medialis) and an external (lamina lateralis); the latter is the broader, and is 
directed backwards and slightly outwards. Its external surface has been already 
studied in connexion with the zygomatic fossa (p. 152). Internally it is separated 
from the inner pterygoid plate by the pterygoid fossa (fossa pterygoidea), wherein 
is lodged a considerable part of the internal pterygoid muscle. The floor of the 
fossa is formed in greater part by the coalescence of the two pterygoid plates; but 
at the level of the hard palate the tuberosity of the palate bone appears wedged in 
between the two plates, and so enters into the formation of the floor of the 
pterygoid fossa. The internal pterygoid plate separates the nasal from the 
pterygoid fossa; to the hinder edge of the internal pterygoid plate are attached the 
pharyngeal aponeurosis, the superior constrictor of the pharynx, and the palato- 
pharyngeus muscle. Above, the posterior border of this plate is channelled to 
form the small scaphoid fossa (fossa scaphoidea), which curves outwards over the 
summit of the pterygoid fossa, and furnishes a surface for the origin of the tensor palati 
muscle. The sharp inner margin of this fossa, continuous below with the posterior 
border of the internal pterygoid plate, extends upwards, and on either side of the 
body of the sphenoid forms a blunt pointed process, the pterygoid tubercle, which 
extends backwards towards the apex of the petrous part of the temporal bone. 
Just external to this, and concealed by it, is the hinder extremity of the Vidian 
canal (canalis Vidianis), through which pass the Vidian vessels and nerve. The 
inner surface of the internal pterygoid plate is directed towards the nasal fosse. 
Superiorly this surface curves inwards to meet the under surface of the body of the 
sphenoid, forming on either side a lipped edge, the vaginal process (processus vaginalis), 
between which the ale of the vomer, which here forms the nasal septum, are 
wedged. Between the twoa small interval, however, is occasionally left, which forms 
on either side the basi-pharyngeal canal. A little external to the line of union of 
the vaginal process with the vomer is the opening of the pterygo-palatine canal 
(canalis pharyngeus). This les between the under surface of the vaginal process 
and the sphenoidal process of the palate bone, which here articulates with the 
inferior surface of the body of the sphenoid. The pharyngeal branch of the 
spheno-palatine ganglion and the pterygo-palatine artery pass through this canal. 
Inferiorly the pterygoid processes project below the level of the hard palate. The 
inner plate ends in a slender recurved process, called the hamular process (hamulus 
pterygoideus), which turns backwards and outwards; this is frequently broken offin 
skulls which have been roughly handled. It reaches as low as the level of the 
alveolar margin, and hes just within and behind the posterior extremity of the 
alveolar process. It can readily be felt in the living by placing the finger against 
the soft palate behind and just within the gum around the root of the wisdom 
tooth. On the front of and below this process the tendon of the tensor palati 
muscle glides in a groove. 
The posterior nares (choanx) he within and between the pterygoid processes. 
Of a shape much resembling two Gothic windows, their bases or inferior boundaries 
are formed by the horizontal plates of the palate bone. Externally they are 
