OF THE NEBVUS OCTAVUS. 



11 



vena jugularis and the N. facialis having been preserved, the fascia 

 is sectioned along the anterior border of the glandula parotis, that 

 is pushed backward, under the root of the ear, by means of a 

 third blunt wound-holder. 



The operator now seeks his direction by the aid of the mem- 

 branous auditory meatus , and determines the place where it passes 

 into the bony part of it. 



The periosteum lying on its surface is sectioned by means of 

 a small, solid and sharp bone-knife and is pushed aside. Before 

 proceeding directly to the bulla ossea, the periosteum along the 

 anterior border of the processus inastoideus is removed, continually 

 staying proximal to. the place where the N. facialis leaves the bone, 

 until the insertion of the 

 in. biventer may be 

 plainly seen. This inser- 

 tion is lifted upward and 

 is sectioned close to 

 where it is affixed to the 

 bone , (See fig. 2 and 

 fig. 3). In this way a 

 large space is obtained 

 and the bony auditory 

 meatus may be seen pas- 

 sing into the bulla ossea, 

 this latter appearing as 

 a, smooth hemisphere of 

 glossy white colour. (See 



fig. 3). 



Next it is ascertained 

 again that the vena jugu- 

 laris and the N. facialis 

 are not endangered. One 

 must make likewise sure 

 that nothing becomes 

 visible, either of the 

 arteria carotis or of the 



nerves leaving the bony meat, audit, osseus, U vena auric, ant., / N. facialis. 



skull at the posterior wall of the bulla ossea, 



This latter point is of the utmost importance. For the sectio- 

 ning of the m. biventer in order to obtain more space, simple though 

 it may be for an experienced operator, may become an obstacle. 

 If, in lying bare the processus mastoideus , the knife of the operator has 



-^ D 



c 

 Fig. 2. 



The vena jugularis is kept under the ascendent branch of the 



maxilla. 

 The m. biventer crosses the field of the operation. The 



N. facialis also crosses it. 



A maxilla inferior, B bulla ossea, Cm use. biventer, D Procesms 

 mastoideus, E Pars mastoidea F meat, audit, membraiiaceus, G 



