32 TREPHINING THE MAXILLARY SINUSES. 



the proper point for operation by percussion or otherwise. 

 If it is desired to enter only the superior maxillary sinus, 

 SM, Plates III-VII locate the opening^ immediately beneath 

 the orbital cavity and in front of the zygomatic ridge, SM, 

 Plate III, or at any point directly beneath this to midway 

 between SM and IM, Plate III, at about the level of the 

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

 sinus at its lowest part, the trephine opening needs be 

 located just in fronts oLjh e lower end of ths-— zygomatic 

 ridge at IM, Plate III, or on -a line obliquely upwards there- 

 from as fa r as the furrow marking the suture T)etween The 

 r naxillary and nasal bones at IM'. The trephining is 

 carried out as described for the frontal sinuses. After the 

 trephining has been completed remove any purulent collect- 

 ion 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 one at the necessary point. 

 Under the influence of disease the sinuses may extend far 

 beyond their normal location or may contract or become 

 largely obliterated by being filled with new bone or soft 

 tissue. The median portion of the sinuses on the inner 

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

 IV-VII, can not be drained properly through the openings 

 SM and IM Plate III, and provision for this must generally 

 be made by trephining into the inferior maxillary sinus at 

 IM', Plate III, and then making an opening 3 to 5 cm. in 

 diameter through the inferior turbinated bone at IT, Plate 

 VIII, either with the finger, probe-pointed bistoury, or 

 other suitable instrument, and inserting through this open- 

 ing a long and thick strip of gauze which is brought out 

 through the nostril and the euds tied together on the side 

 of the face to prevent displacement. Retain this in position, 

 renewing daily until the permanency of the opening is as- 

 sured. 



