BONES, OF THE FACE. 199 



To the practical dentist, Mr. Nasmyth uses the follow- 

 ing strong language in reference to these bones : "These 

 bones serve most importantly to render the upper jaw 

 pliant during the actions of the mouth in the early years 

 of life, and they are also of high account in promoting by 

 their growth the latitude necessary for the proper arrange- 

 ment of the teeth. As a means also of preventing concus- 

 sion of the teeth, they are valuable accessories in the 

 mechanism of the mouth." He thus describes their anat- 

 omy : a ln the foetal skull, at the point of junction of the 

 posterior with the middle third of the foramen incisivum, 

 a fissure may be observed, which passes upwards into the 

 anterior palatine canal on each side, and may be traced 

 onwards to the floor of the nasal cavity. Having reached 

 the latter situation, it inclines obliquely backwards and 

 outwards for the distance of about a line, and then bends 

 forwards and upwards for a space of two or three lines to 

 the base of the nasal process of the superior maxillary 

 bone, terminating upon the latter at one or two lines below 

 the ridge for the inferior turbinated bone. If the foramen 

 incisivum be again examined, another fissure will be ob- 

 served on the oral surface of the palate, passing directly 

 outwards to the alveolus of the canine tooth, and curving 

 gently backwards in its course. The portion of bone which 

 lies anterior to these fissures on each side, and which sup- 

 ports the incisor teeth, is the inter-maxillary bone."* 



This surface is also called the palatine process of the 

 superior maxillary bone. It is smooth and concave above, 

 where it forms the nares, and rough below where it forms 

 the mouth. Its anterior boundary is very thick, and con- 

 stitutes the alveolar arch and processes. 



This arch has eight conical cavities for the teeth, and 

 when united with its fellow, completes the circle and con- 

 tains sixteen in all. The cavities are separated by parti- 

 tions of dense cellular tissue, and have their shape corre- 

 sponding to the variety of teeth they accommodate. The 

 walls of these cavities form the alveolar processes. The 



* Nasmyth's late Researches. 



