36 TREPHINING THE NASAL FOSSAE. 



5. TREPHINING THE NASAL FOSSAE. 



Uses. Operations on the septum iiasii, upon the tur- 

 binated bones, the removal of tumors or foreign bodies. 



Instruments. Same as for the frontal sinuses. 



Technic. The trephining is carried out bj' the method 

 described above, in the region of 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, Plate IV, to 

 the upper extremity of the false no.stril. The operation 

 should be immediately against the median line since other- 

 wise the frontal or superior turbinated .sinuses may be 

 opened, the highly vascular superior turbinated- bone 

 wounded or an important inter-osseous artery in the nasal 

 bone just above its union with the superior turbinated bone, 

 as shown in Plate VI, may be severed. Special care is also 

 necessary that the trephining should not be carried too 

 deeply and that the disc of bone be carefully removed in 

 order to avoid wounding the liighlv va.scular 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 opera- 

 tion should be carried out on the standing animal which de- 

 creases the hemorrhage and the danger from aspiration of 

 fluids. Even in the standing animal, if extensive operations 

 are to be carried out on the very vascular septum na.sii or 

 on the turbine it is generally advisable to perfom trache- 

 otomy before trephining, and retain the trachea tube in 

 position until all danger has passed. When the animal is 

 confined in the recumbent position the patient's safety de- 

 mands that tracheotomy be performed before the operation 

 is begun in almost all cases. Anaesthesia may be maintained 

 in such ca.ses by means of an ordinary funnel with its .'spout 

 bent at right angles and inserted into the trachea tube while 



