TREPHINING THE NASAL FOSSAE 33 



Instruments. Same as for the frontal sinuses (page 17). 



Technic. The trephining, N, Fig. 3, is carried out by the 

 method described above, in the nasal bone, close by the 

 median line of the face and according to indications at any 

 point from a level of the dotted line, SM,__F[g^ to the 

 juncture_beUyee,n_tliejiasaL^a nd pre^ maxillary bones^liear 

 "TEeUpper extremity of the false nostril. 



A study of Figs. 7-10 will show that the trephining of 

 these cavities requires great care in order to avoid wound- 

 ing either the highly vascular septum nasi or even more 

 vascular turbinated bones. The operation ,§hould be im- 

 mediat ely ag ainst the^septuni since otherwise the superior 

 turbinated bone may be wounded or an important intra- 

 osseus artery in the nasal bone, just- above its union with- 

 the superior turbinated, as shown in Fig. 9, may be severed. 



If the turbinated bone is penetrated the frontal, and 

 through it, the superior maxillary sinus is opened and ex- 

 posed to infection with all its consequences. Special care 

 is accordingly necessary that the trephining should not be 

 carried too deeply, that the bone be barely penetrated, and 

 that the osseous disc be carefully removed in order to avoid 

 the wounding of the turbinated bone, which lies in close 

 proximity to the nasal bone. The operative area is narrow 

 and the trephine used should not exceed 2 cm. in diameter. 



Whenever possible the operation should be carried out 

 on the standing animal which decreases the hemorrhage 

 and the danger from the inhalation of fluids. The hemor- 

 rhage may be further controlled in operations upon the 

 septum nasi and turbinated bones by spraying the parts with 

 adrenaline chloride and cocaine. Even in the standing 

 animal, if extensive operations are to be carried out on the 

 very vascular septum nasi or on the turbine, it is advisable 

 to preform trachetomy before trephining, and retain the 

 trachea tube in position until all danger has passed. When 

 the animal is confined in the recumbent position, the 



