12 



C. WINKLER. THE CENTRAL COURSE 



A 



deviated too much towards the foramen of the occiput , after the section 



of the m. biventer, not 

 only the bony audi- 

 tory meatus with the 

 anterior surface of the 

 bulla ossea, but also 

 the medio-distal wall 

 of it becomes visible. 

 Next to this latter is 

 situated the foramen 

 jugulare, and the ope- 

 rator will state to his 

 dismay that as soon 

 _^ as the m. biventer is 

 sectioned, the arteria 

 carotis and the four 

 nerves appear within 

 the area of operation 

 (See fig. 4). 



Beginning from the 

 centre , these are the 



The position of the meatus auditoreus osseus, of the processus TVT lavviio'pne em^p 



mastoideus and of the bulla ossea, ^ ' ^J 11 ^ 1 



after the cleaving of the m. biventer. rioi* the N hvDO- 



A maxilla inferior, B bulla ossea, C proc. mastoid . , D meat. rr1rcnc i\\r* "NT 

 audit, osseus. E meat. aud. membranaceus , F N. facialis. glOSSUS , llie 1\ . S\ 111- 



pathicus and the N. 



vagus. All these ought not to be seen , neiher in this stage of the 

 operation nor afterwards, when the bulla ossea is opened. For if 

 the bulla ossea is opened too far distalward, and the mediodistal 

 wall does not remain firm , but is ruptured and has too be 

 removed , the nerves will appear again. The danger of their being 

 injured is even very great in the latter case, as well as that of 

 injuring the well-protected N. facialis. 



If one or several of these nerves are injured, the danger arises 

 again of occasioning uncontrollabe retrograde degenerations. In a 

 faultless operation however neither the arteria carotis nor one of 

 the afore-said nerves may have been seen by the operator. 



The anterior wall of the bulla ossea and the passage of the 

 bony auditory meatus into the bulla ossea. are now lying before the 

 operator, who supports the bulla by wadding and either punctions 

 the top of its hemisphere with a pair of small crooked nibling 

 pincers or else opens it with a sharp chisel. The supporting of 

 the bulla is necessary in order to prevent eventual fissures exten- 



