14 TREPHINING THE FACIAL SINUSES 



The fracture of the superior maxilla and bony palate is 

 not so probable as the preceding and is preventable by mod- 

 erate care in the denuding of the tooth before punching, by 

 comminution of the tooth in proper cases, by the careful 

 adjustment of the punch and by applying the force in the 

 pxoper direction. 



Literature. Odontomes, Sir Bland Sutton, Jour. Comp. 

 Med. and Vet. Arch, Vol. XII. p. i ; A Clinical Study of 

 Odontomes, W. L. Williams, Am. Vet. Review, Vol. XV, 

 p. I ; Notes on Odontomes, do ; Am. Vet. Rev. Vol. XXIII, 

 p. 82 and Oest. Mon. Thierheilkunde, Bd. XXIV, s. 122. 



TREPHINING THE FACIAL SINUSES 

 Figs. 3-11 



The facial sinuses of the horse constitute 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 fre- 

 quently 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 relation to each other and to surrounding 

 parts vary greatly with age. They may also be profoundly 

 changed as a result of disease, resulting not infrequently 

 in the frontal, superior and inferior maxillary sinuses ceasing 

 to exist as separate compartments and becoming merged 

 into one vast cavity. The general position, extent and re- 

 lation of these are indicated by Figs. 3-1 1. 



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- 



