TREPHINING THE MAXILLARY SINUSES. 33 



4. TREPHINING THE MAXILLARY SINUSES. 



Uses. Empyema, diseased teeth, odontomes, tumors. 



Instruments. Same as for the frontal sinuses. 



Anatomically there are two maxillary sinuses, superior 

 SM, and inferior IM, Plates IV, V, and VI, having a thin 

 imperforate bony partition between them. This partition 

 shifts somewhat in position with age and in case of disease 

 undergoes profound changes in location and is frequently 

 totally. obliterated in cases of empyema, dental cysts and 

 other affections, so that clinically in many cases its location, 

 existence or non-existence is of scant interest. If present, 

 good drainage of the superior sinus usually demands its 

 surgical destruction so that most authors advise trephining 

 directly over this partition in order to open the two sinuses 

 simultaneously. In extensive disease the prior destruction 

 of the partition renders such an operation superfluous ; in 

 limited disease the opening of both cavities is ill advised. 

 The partition should be ignored in operating for extensive 

 disease and the trephine opening be aimed at the probable 

 focus of disease and, if missed, it should be located through 

 the primary, or what now becomes an exploratory opening 

 and a second operation made to directly reach the seat of the 

 affection and if need be, yet a third to secure proper drain- 

 age. Shave and disinfect as much of the area as may be re- 

 quired bounded above by the inferior border of the orbital 

 cavity, laterally by the zygomatic ridge, inferiorly by the 

 lower end of the zygomatic ridge and medianwards by the 

 middle line of the face. Determine the proper point for 

 operation by percussion or otherwise. If it is desired to 

 enter only the superior maxillary sinus, SM, Plates V and 

 and VI, locate the opening immediately beneath the orbital 

 cavity and in front of the zygomatic ridge, SM, Plate IV, or 

 at any point directly beneath this to within about 3 or 4 cm. of 

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