SM 



FIG. 6. 

 Trephining of Facial Sinuses. 



Frontal view of right side of face with sinuses exposed. SM, 

 superior maxillary sinus ; IM', median portion of inferior maxillary 

 sinus ; IM, lateral portion of inferior maxillary sinus ; F, frontal sinus ; 

 FE, communication between the frontal and superior maxillary sinuses. 



