TREPHINING THE NASAL EOSSAE. 



49 



A study of Plates VII-X 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 should be im- 

 mediately against the septum since otherwise the superior 

 turbinated bone may be wounded or an important intra- 

 osseous artery in the nasal bone, just above its union with 

 the superior turbinated, as shown in Plate IX, 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 Hes 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 aspiration of fluids. The hemorrhage 

 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 

 patient's safety demands that tracheotomy be performed in 

 almost all cases before any operation is begun upon the 

 septum nasi or turbinated bones. After tracheotomy, 

 anaesthesia may be maintained by means of an ordinary 

 funnel with its tube bent at right angles and inserted into 



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