MEMBRANA PROPRIA OF THE DUCTUS COCHLEARIS. 149 



strongest, and perhaps also the highest crista, together with 

 extraordinarily sharp teeth, which are curved almost into the 

 form of claws. The height and size diminish in proportion 

 as the cupola is approximated. In regard to the physiological 



Fig. 325. 



Fig. 325. Crista spiralis, after the removal of all the investing 

 structures. From a woman aged 28. Vestibular surface view. Magni- 

 fied 300 diameters ; a, Labium tympanicum of the crista (point of tran- 

 sition into the membrana basilaris, at the botom of the sulcus spiralis 

 internus) ; b o, auditory teeth of the labium vestibulare ; below c, is 

 the sulcus spiralis internus, as seen in perspective, enclosed by its 

 two labia ; d d, processes of the crista ; e e, sections of small processes ; 

 //, grooves between the processes, which gradually diminish in depth 

 towards </, and are ultimately continuous with the plane of the lamina 

 spiralis ossea ; bone corpuscles are indistinctly visible. 



significance of this remarkable structure, no opinion has hither- 

 to been formed, except that it constitutes a support to the 

 membrana tectoria. 



