TREPHINING OF THE FRONTAL SINUSES. 



19 



manner so far as we can observe clinically by the direct ad- 

 mission of air into them through a trephine, or other artificial 

 opening, but on the contrary the suppuration in a sinus is 

 constantly aggravated by the retention of the pus and ex- 

 clusion of air and recovery facilitated by thorough drainage 

 and aeration. 



3. TREPHINING OF THE FRONTAL SINUSES. 

 Plates III-XI. 



Uses. Fracture of the bonj' walls, necrosis, tumors. 



The ample communication below with the superior 

 maxillary sinus (See FE, Plates V and VI ) prevents the 

 accumulation of pus or fluids in the frontal sinuses even if 

 formed therein unless the former becomes filled and the 

 contents back up into the latter. In empyema of the 

 frontal sinuses, trephining can not give relief, but calls for a 

 repetition of the operation on the maxillary sinuses. 



Instruments. Razor, scissors, convex scalpels, artery 

 forceps, tenacula, probe, trephine, curette, gouge, Luer's 

 sharp bone forceps (rongeur forceps), hammer, chisel, 

 probe-pointed bistoury, dressing forceps, disinfecting and 

 dressing materials. 



Technic. The operation may be performed upon the 

 standing animal with the aid of local anaesthesia of the 

 skin, the bone having virtually no sensation. Restless 

 animals may be further secured with the twitch, in the 

 stocks, upon the operating table or bj' casting on the sound 

 side. 



Clip and shave the hair from the region of the frontal 

 bone at that point which the operator has reason to believe 

 is nearest the center of disease. The highest point at which 

 the sinus may be trephined is indicated by F in Plate III. 

 The most central portion of the cavity is reached by trephin- 



