Plate VII. 



Trephining of Facial Sinuses. 



Cross section of the right half of the head of 

 a horse at the posterior border of the last molar. 

 F, frontal sinus ; IM, lateral portion of inferior 

 maxillary sinus at extreme posterior or superior 

 part ; IM^, median portion do,; N, nasal cham- 

 ber opposite the communication between it and 

 the superior maxillary sinus ; NF, conduit of 

 superior maxillary branch of the trifacial nerve ; 

 vSM, superior maxillary sinus ; M', fragment of 

 last molar. 



