136 THE AUDITOKY NERVE AND COCHLEA, BY W. WALDEYER. 



In the subsequent pages we shall call the surface looking towards 

 the modiolus of the cochlea the "internal" (mesial), and that turned 

 to the external wall of the osseous cochlear canal as the " external " 

 (lateral). Everything that runs in the direction from the axis to the 

 external wall, we name "radial," and, on the contrary, everything follow- 

 ing the course of the cochlear walls, " spiral " (Henle). Lastly, those 

 surfaces which are turned towards the vestihular scala, or towards 

 the tympanal scala, are termed " vestibular " or " tympanic." * 



Touching the development of the cochlea, to which I can 

 here only devote a few remarks, it may be stated, that in 

 human embryoes of from eight to ten weeks of age, three 

 several textural constituents are distinctly visible in the region 

 of what subsequently undergoes development into the pars 

 petrosa of the temporal bone ; externally is a cartilaginous 

 mass, which is at this period continuous with the rest of the 

 cartilaginous basis cranii ; next, enclosed by the cartilage, is a 

 large spheroidal mass of embryonal mucous tissue, within 

 which, again, the epithelial labyrinth-vesicle is imbedded. 

 From the -same part of the latter that subsequently corre- 

 sponds to the sacculus, a hollow epithelial projection is thrust 

 out, even before the eighth week, which, gradually becoming 

 wider, penetrates into the mucous tissue, and, owing to the 

 presence of the surrounding denser capsule, is compelled to 

 wind spirally in its soft bed. At one point the cartilaginous 

 capsule is incomplete, and here the.ramus cochlearis of the 

 auditory nerve enters. Human embryoes of three months 

 exhibit the hollow epithelial projection, and the rudiment of 

 the ductus cochlearis, with its several coils. In embryoes of 



Corti ; L sp, lamina spiralis ; Gfl, Gh, ganglion spirale with various 

 afferent and efferent nerve fasciculi ; ST, scala tympani ; SV, scala 

 vestibuli ; ST 1 , SP } , ST^, mucous tissue of the subsequently forming 

 scales in the last turn of the cochlea. 



* There is scarcely any region of the body so small in extent as that of 

 the cochlea which possesses so rich and complicated a nomenclature. 

 The confusion is not diminished by the practice, little worthy of com- 

 mendation, but adopted by many authors who have given a fresh descrip- 

 tion of long-known structures, of inventing a series of new names. 

 Perhaps the terms now employed may not appear to be inappropriate to 

 my fellow-workers. Scarcely any new ones have been added, whilst 

 many superfluous and duplicate terms have been simplified. 



