114 



THE EAR. 



or ductus cochlearis (fig. 127, cc ; figs. 128, 129). It terminates in a blind extremity 

 at the apex (lagena), 1 and another at the base. That at the apex, extending 



membrana scala 

 tectoria restibuli 



membrana scala 



ganglion spirale Reissneri vestibuli 



/neat us 

 auditorius 

 internus 

 fovea cochleae) 



membrana 

 basilaris 



ganglion 

 spirale 



scala 

 tympani 



membrana 

 basilaris 

 Fig. 129. SECTION THROUGH THE MIDDLE OP THE COCHLEA, DIAGRAMMATIC. (E. A. S.) 



beyond the hamulus, is fixed to the wall of the cupola, and partly bounds the helico- 

 trema ; that at the base fits into the angle at the commencement of the osseous 



stria vascular is T,. , -. 



Fig. 130. APEX OP COCHLEAR 



CANAL. (Retzius.) 



spiral lamina in front of the 

 floor of the vestibule. Near 

 to this blind extremity the 

 canal of the cochlea receives a 

 small canal, lined with epithe- 

 lium, cmialis reuniens (Hen- 

 sen), which is continued from 

 the saccule of the vestibule 

 like a neck of a flask, and 

 enters the canal of the cochlea 

 abruptly nearly at a right 

 angle (figs. 117, 118, ID). 

 The cavity of the canal of the 



cochlea is thus rendered continuous with that of the saccule. The structures which 

 are found upon the floor of this spirally- wound triangular canal of the cochlea 

 claim more particular attention, for it is to them that the branches of the cochlear 

 nerve are distributed, and upon them the function of the cochlea as a part of the 

 auditory apparatus appears more especially dependent. 



1 In monotreraes and in birds, reptiles, amphibia, and fishes, there is a specially modified patch of 

 auditory epithelium at the lagena, similar to the maculae of utricle and saccule, and provided with 

 otoliths. In fishes this is the only nerve-terminal apparatus in the cochlea, which is also otherwise quite 

 rudimentary. 



lagena 



hamulus bundles of 



cochlear nerve 



organ of Corti. 



