59 8 



NERVES OF THE COCHLEA. 



[sect. 234. 



Fig. 24G. 



on the sulcus spiralis ; but on account of the readiness with which 



the cells become separated, it is ex- 

 tremely difficult to arrive at a com- 

 plete idea of their arrangement. 



The nerves of the cochlea pass from 

 the canals of the modiolus into the 

 spaces of the osseous zone, and here 

 form a dense plexus with dark bor- 

 dered tubes, o - ooi5'" in diameter, 

 throughout the whole extent of the 

 osseous lamina. According to Corti's 

 discovery, this plexus contains (at a 

 very definite spot near the margin of 

 the zone) a collection of nerve-cells, 

 which is at first o*i'" in breadth. These 

 ganglionic cells are small, pale, oval, 

 bipolar bodies, measuring crou"' to 

 <roi6'" in length, croo66'" to 0*0097'" 

 in breadth ; in all probability, they 

 interrupt all the fibres of the cochlear 

 nerve in their course. The dark bor- 

 dered nerve-tubes which are given off 

 externally from these cells, collect 

 once more into flat anastomosing bun- 

 dles, which, after interlacing, run 

 parallel to each other; they become 

 looser and looser towards the hamulus, 

 and in that situation the fibres are to 

 be seen forming a simple layer, and 

 even separated by interspaces. The 

 termination of these nerves takes 

 place in a single definite line for all 



but 



Perpendicular section through part of 

 the lamina spiralis. From the second 

 turn of the cochlea of an ox ; treated 

 with diluted hydrochloric acid ; mag. 

 ISO times. The organ of Corti is let- 

 tered as in the preceding preparations. 

 a. periosteum and softened layer of 



hone on the aspect of the zona ossea, the parallel bundles and tubes 

 towards the scala vestibuli; &. hahenula - _ pi 



sulcata (Corti) with a capillary loop ; in the first turn of the COChlea tlllS 

 c. teeth of the first series ; d. sulcus 

 spiralis lined with epithelium ; e. hahe- 

 nula perforata (mihi) ; /. foramina 

 through which the nerves pass from the 

 scala rympani into the scala vestibuli ; 

 g. bipolar cells at the commencement 

 of a Cortian fibre ; h. posterior, and ifc, 

 anterior segment of the Cortian fibre ; 

 i. pedunculated nerve-cells ; I. nerve 

 within the zona ossea ; m. end of its 

 dark-bordered fibres; n. lower tympanic 

 periosteal lamella ; 0. lamina spiralis 

 membranacea; p. lig. spirale; q. thin 

 part of membrana Cortii. 



0*03"', the nervous terminations lie beyond the bony plates upon 



line is found somewhat nearer the 

 outer wall than in the subsequent 

 turns. Moreover, in the first turn, 

 the terminations lie within the two 

 plates of the osseous zone, reaching 

 exactly to the margin of it; in the 

 second turn, for a space of 0*02"' to 



