IN HERBIVOROUS ANIMALS. 
221 
establishes itself in the areoles of the spongy tissue ; but in this 
case (when the upper jaw is the seat of the disease) the vicinity 
of the nasal cavities and the sinuses induce complications, the 
study of which is exceedingly important. 
In this place it is necessary for us, in order completely to facili- 
tate this study, to take carefully into consideration the seat of the 
diseased tooth. The two first molars do not communicate with the 
sinuses of the head, but their roots are immediately applied upon 
a partition exceedingly thin, and which separates them from the 
principal parts of the nasal cavities. We can, therefore, conceive 
how, in the consequence of caries of one of the teeth, the inflamma- 
tion can extend itself even to the membrane which lines these cavi- 
ties, and, also, how it is possible that a perforation of the osseous 
partition may establish a communication between the mouth and 
the nose. 
Under the influence of interstitial suppuration determined by 
caries in the spongy tissue of the alveole, the osseous membrane 
can, in fact, be destroyed to an enormous extent ; the alimentary 
matters then find a road open through the dental fistula to pene- 
trate into the nose, and to be rejected by the nostrils with the 
product of the morbid secretion of the pituitary membrane. 
The third molar approaches the maxillary sinuses, from which 
the root is separated by a thin diaphragm ; but it deserves to be 
separately noticed, on account of an anatomical particularity, which 
renders the caries of this tooth very much to be dreaded. We wish 
to speak of the position of large fascim of the fifth pair of nerves, 
which makes its exit upon the face by the submaxillary foramen, 
and which is placed immediately upon the extremity of the third 
molar. It is easy to have a presentiment of what terrible pain 
and what nervous complications must be produced by the caries of 
this tooth, when it has determined in the tissue of the alveole such 
grave alterations as those of which we have just spoken. 
The position of the last of the superior molars, immediately below 
the vast maxillary sinuses, from which their roots are separated 
only by an osseous pellicle, gives to the caries of these teeth, and 
to the complications which it induces, a special character, which 
demands that we should speak of it with some detail. 
Where the caries is prolonged to the roots of the three last 
molars, and has induced an explosion of this inflammation, of 
which we have just spoken, into their alveoles with such thin 
parietes, the partition that separates them from the sinus does 
not resist very long. Destroyed by the dilatory effort of the 
hypertrophied root, and by the influence of the caries, it gives way 
and permits to the altered matters of the mouth a free access into 
the cavities of the sinuses. Under the influence of their contact 
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