1 6 TREPHINING OF THE FACIAL SINUSES. 



TREPHINING OF THE FACIAL SINUSES. 

 Plates III- XL 



Prefatory Note. The facial sinuses of the horse consti- 

 tute an exceedingly intricate and extensive group of cavities, 

 communicating more or less freely with each other or with 

 the exterior through the medium of the upper air passages, 

 of which they are to be regarded as a part. 



Their arrangement and relations permit them to frequently 

 become the seat of, or central figure in many forms of disease 

 which require for their differential diagnosis, amelioration 

 or cure, the operation known as trephining. Their extent 

 and relations to each other and to surrounding parts varies 

 greatly with age and may be profoundly changed as a result 

 of disease, amounting not infrequently in the frontal, 

 superior and inferior maxillary sinuses ceasing to exist as 

 separate cavities and becoming merged into one vast diverti- 

 culum. The general position, extent and relations of these 

 are indicated by Plates III-XI. 



It is to be noted that in cross .sections the superior and 

 inferior maxillary sinuses appear to be reversed in relation 

 to their nomenclature. It is difficult to make a cross .sec- 

 tion of these sinuses in such a manner that the antero- 

 inferior extremity of the superior sinus does not show below 

 and external to the inferior one. The inferior maxillary 

 sinus is ifi/erior in the sense that it is nearer to the nasal 

 opening so that with the head in a vertical position or in a 

 longitudinal section the inferior sinus is below the superior, 

 while if the head be placed horizontally or a cross section 

 made, a small portion of the superior sinus may show below 

 the inferior. 



The uses of trephining are in a measure common to all 

 the sinuses and are chiefly for the relief of empyema of the 

 cavities involved, necrosis of the bony or cartilaginous walls,, 

 tumors of various kinds, especially dental in the young and 



