THE BONES OF THE HEAD 



113 



nerves and arteries. Internally the tuberosity gives origin to a 

 few fibres of the superior constrictor muscle of the pharynx. 

 Externally there is a small free surface, which looks into the 

 zygomatic fossa, between the pterygoid process of the sphenoid 

 and the tuberosit}' of the superior maxilla. 



The orbital process surmoimts the anterior border of the per- 

 pendicular plate. It is of large size, and presents six surfaces, 

 three of which are articular. The superior or orbital surface forms 

 a small part of the floor of the orbit posteriorly. The external 

 or spheno-maxillary surface looks into the spheno-maxUlary fossa. 

 The anterior or maxillary surface is continuous with the external 

 surface of the perpendicular plate, and articulates with the back 

 part of the internal border of the orbital surface of the superior 

 maxilla. The internal or ethmoidal surface, which is excavated, 

 articulates with the lower border of the os planum of the 



Post, or Sphenoidal Surf, of Orbital Proces 



Superior or Sphenoidal Surface . ^ 

 of Sphenoidal Process 



Groove for Pterygo-palatine Canal — -' 



Inferior Turbinate Crest 



Nasal Crest 



Posterior Nasal Spine / 



Horizontal Plate' 



For Int. Pterygoid Plate of Sphenoid ' 



Superior or Orbital Surface 



. _.Ext. or Spheno-maxillary 

 Surface 



>Spheno-palatine Notch 



.Groove for Post. Palatine Canal 

 (on Ext. Surf.) 



, For Pterj-goid Fossa of Sphenoid 



For Ext. Pterygoid Plate 



of Sphenoid 



Tuberosity 



Fig. 70. — The Right Palate Bone (Posterior View). 



ethmoid at its back part, close to the postero-inferior angle. The 

 posterior or sphenoidal surface small and excavated, articulates 

 ; with the front of the body of the sphenoid, and, as a rule, com- 

 municates with the sphenoidal air sinus. The inferior or nasal 

 surface is continuous with the internal surface of the perpendicular 

 plate, and forms part of the outer wall of the nasal fossa at its 

 upper and back part, where it overhangs the groove for the superior 

 meatus. 



The sphenoidal process surmounts the posterior border of the 

 perpendicular plate, and is shghtly incurved. It presents three 

 surfaces, and three borders. The superior or sphenoidal surface, 

 wluch is grooved, articulates with the inferior surface of the body, 

 and the vaginal process, of the sphenoid. The groove on this 

 surface, with that on the under surface of the vaginal process, forms 

 the pterygo-palatine canal for the pharyngeal nerve and pterygo- 

 palatine artery. The internal or nasal surface is scooped out, and 



