54 THE BONES OF THE HEAD. 



bone ; and at the upper end of the surface, crossing the roots of the two processes, 

 is another less marked ridge, the ethmoidal or superior turbinate crest, which articu- 

 lates with the middle turbinate bone. The external surface presents, nearer to the 

 posterior border, a narrow smooth surface which forms the inner wall of the pterygo- 

 maxillary fissure, and leads down to a deep groove forming with the superior maxil- 

 lary bone the palato-maxillary or posterior palatine canal for the transmission of 

 the large palatine nerve and vessels ; in front of the groove the surface is applied 

 against the superior maxillary bone, and overlaps the orifice of the antrum by a thin 

 tongue-shaped projection, the maxillary process, which may attain a considerable 

 size ; behind the groove it articulates inferiorly with the hinder border of the 

 maxilla, superiorly with the inner surface of the pterygoid process. 



SPHEN. PAL, NOTCH 



A POST. NASAL SPINE 



Fig. 54. RIGHT PALATE BONE: A, OUTER VIEW ; B, IKNER VIEW. (Drawn by D. Gunn.) 



The pyramidal process or tuberosity fits into the notch between the pterygoid 

 plates. It presents posteriorly a triangular surface which is concave and smooth, 

 and completes the pterygoid fossa : on each side of this is a narrow area, the 

 internal deeply grooved, the external rough, for articulation with the anterior 

 border of the corresponding pterygoid plate. Externally there is a small free 

 surface which appears between the tuberosity of the superior maxillary bone and the 

 pterygoid process in the zygomatic fossa (fig. 68). Inferiorly, close to its con- 

 nection with the horizontal plate, are the orifices of the posterior and external 

 accessory palatine canals which transmit the lesser palatine nerves ; the external is 

 the smaller and less constant. 



The orbital process surmounts the anterior margin of the vertical plate. It is 

 somewhat pyramidal in shape, and has five surfaces, two of which, the superior and 

 external, are free, and the rest articulated. The superior surface forms the posterior 

 angle of the floor of the orbit (fig. 69), the external looks into the spheno- 

 maxillary fossa, the anterior articulates with the maxillary, the internal with the 

 ethmoid, and the posterior, which is small, articulates with the sphenoid. The 

 process is generally hollow, and the cavity completes one of the posterior ethmoidal 

 cells, or it may open behind into the sphenoidal sinus. 



The sphenoidal process curves upwards and inwards from the posterior part 

 of the vertical plate. Its superior surface is in contact with the body of the 

 sphenoid and the base of the internal pterygoid plate, and is grooved for the com- 

 pletion of the pterygo-palatine canal ; its internal or under surface looks to the 



