168 



OSTEOLOGY 



The maxillary surface is rough and irregular throughout the greater par 

 extent, for articulation with the nasal surface of the maxilla; its upper and buck 

 part is smooth where it enters into the formation of the pterygopalatine fossa; 

 it is also smooth in front, where it forms the posterior part of the medial wall 

 of the maxillary sinus. On the posterior part of this surface is a deep vertical 

 groove, converted into the pterygopalatine canal, by articulation with the maxilla; 

 this canal transmits the descending palatine vessels, and the anterior palatine 

 nerve. 



Borders. The anterior border is thin and irregular; opposite the conchal crest is a 

 pointed, projecting lamina, the maxillary process, which is directed forward, and 

 closes in the lower and back part of the opening of the maxillary sinus. The 

 posterior border (Fig. 169) presents a deep groove, the edges of which are serrated 

 for articulation with the medial pterygoid plate of the sphenoid. This border 

 is continuous above with the sphenoidal process; below it expands into the 

 pyramidal process. The superior border supports the orbital process in front and the 

 sphenoidal process behind. These processes are separated by the sphenopalatine 

 notch, w 7 hich is converted into the sphenopalatine foramen by the under surface of 

 the body of the sphenoid. In the articulated skull this foramen leads from the 

 pterygopalatine fossa into the posterior part of the superior meatus of the nose, 

 and transmits the sphenopalatine vessels and the superior nasal and nasopalatine 

 nerves. The inferior border is fused with the lateral edge of the horizontal part, 

 and immediately in front of the pyramidal process is grooved by the lower end 

 of the pterygopalatine canal. 



The Pyramidal Process or Tuberosity (processus pyramidalis) . The pyramidal 

 process projects backward and lateralward from the junction of the horizontal 

 and vertical parts, and is received into the angular interval between the lower 

 extremities of the pterygoid plates. On its posterior surface is a smooth, grooved, 

 triangular area, limited on either side by a rough articular furrow. The furrows 

 articulate with the pterygoid plates, while the grooved intermediate area completes 

 the lower part of the pterygoid fossa and gives origin to a few fibers of the Ptery- 

 goideus internus. The anterior part of the lateral surface is rough, for articulation 

 with the tuberosity of the maxilla; its posterior part consists of a smooth triangular 

 area which appears, in the articulated skull, between the tuberosity of the maxilla 

 and the low r er part of the lateral pterygoid plate, and completes the lower part 

 of the infratemporal fossa. On the base of the pyramidal process, close to its 

 union with the horizontal part, are the lesser palatine foramina for the transmis- 

 sion of the posterior and middle palatine nerves. 



The Orbital Process (processus orbitalis). The orbital process is placed on a 

 higher level than the sphenoidal, and is directed upward and lateralward from 

 the front of the vertical part, to which it is connected by a constricted neck. It 

 presents five surfaces, which enclose an air cell. Of these surfaces, three are articu- 

 lar and two non-articular. The articular surfaces are: (1) the anterior or maxillary, 

 directed forward, lateralward, and downward, of an oblong form, and rough for 

 articulation with the maxilla; (2) the posterior or sphenoidal, directed backward, 

 upward, and medialward; it presents the opening of the air cell, which usually 

 communicates with the sphenoidal sinus; the margins of the opening are serrated 

 for articulation with the sphenoidal concha; (3) the medial or ethmoidal, directed 

 forward, articulates with the labyrinth of the ethmoid. In some cases the air 

 cell opens on this surface of the bone and then communicates with the posterior 

 ethmoidal cells. More rarely it opens on both surfaces, and then communicates 

 w r ith the posterior ethmoidal cells and the sphenoidal sinus. The non-articular 

 surfaces are: (1) the superior or orbital, directed upward and lateralward; it is 

 triangular in shape, and forms the back part of the floor of the orbit; and (2) the 

 lateral, of an oblong form, directed toward the pterygopalatine fossa ; it is separated 



