34 TREPHINING THE MAXILLARY SINUSES. 



the inferior end of the zygomatic ridge at about the level of 

 the dotted line IM'. In order to penetrate the inferior 

 maxillary sinus the trephine opening needs be located just 

 in front of the lower end of the zygomatic ridge at IM, Plate 

 IV, or on a line obliquely upwards therefrom as far as the 

 furrow marking the suture between the maxillary and nasal 

 bones at IM'. The trephining is carried out as described 

 for the frontal sinuses. After the trephine opening has been 

 made 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 per- 

 fect drainage of the lateral sac, either lower the opening 

 already made by cutting away its inferior border with the 

 bone forceps or make a second trephine opening at the neces- 

 sary point. The median portion of the sinuses on the 

 median side of the bony conduit of the trifacial nerve NF, 

 Plates V and VI, can not be drained properly through these 

 openings SM and IM, Plate IV, and provision for their 

 drainage must generally be made by making a trephine open- 

 ing into the inferior maxillary sinus at IM', Plate IV, and 

 then make an opening 3 to 5 cm. in diameter through the in- 

 ferior turbinated bone at IT, Plate VII, either with the 

 ringer, probe-pointed bistoury, or other suitable instrument, 

 and inserting through this opening a long and thick strip of 

 gauze which is brought out through the nostril and the ends 

 tied together on the side of the face to prevent displacement. 

 Retain this in position renewing daily until the permanency 

 of the opening is assured. 



If the partition between the two sinuses is intact it w r ill be 

 necessary to destroy it immediately above IM', Plate IV, in 

 order to drain the median portion of the superior maxillary 

 sinus if that is required. If a molar has been removed and 

 in so doing the bony wall leading down from the nerve con- 

 duit NF, Plates V and VI, to the fang of the molar has been 

 destroyed in the operation, sufficient drainage may be af- 



