TREPHINING THE SUPERIOR MAXILLARY SINUSES 25 



simultaneously. In extensive disease of either sinus the 

 partition between the two frequently becomes obliterated 

 so that there remains but one ; in limited disease the open- 

 ing of both cavities is ill advised. In extensive disease the 

 existence of a partition may generally be ignored and the 

 trephine opening be aimed at the probable focus of the 

 malady. Should this fail to reach the desired point, 

 the proper location may now be determined by digital or 

 other examination through the first opening. A second 

 operation should then be made to directly reach the seat of 

 the affection and if need be, a third to secure proper 

 drainage. 



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 zygoma, and medianwards by the middle 

 line of the face. Determine the proper point for operation 

 by percussion or otherwise. If it be desired to enter only 

 the superior maxillary siniis, SM, Figs. 3-10, locate the 

 opening beneath the orbital cavity and in front of the zygo- 

 matic ridge, SM, Fig. 3, or at any point directly beneath this 

 to midway between SM and IM, Fig. 3, at about the level 

 of the dotted line IM'. 



The trephining is carried out as described for the frontal 

 sinuses on page 17. After the trephining has been com- 

 pleted remove any purulent collection or tumors or carry 

 out any other necessary operation in the affected sinuses, 

 and after cleansing, if the trephine opening does not insure 

 perfect drainage of the lateral sac, either lower it by cutting 

 away its inferior border with the bone forceps, or make a 

 second trephine opening at the necessary point. 



Since empyema of the superior maxillary sinuses is due in 

 the vast majority of cases to infection derived from diseased 

 teeth or dental alveoli, it is essential after the sinus has been 

 opened that the operator search carefully and minutely over 



