3 86 



HISTOLOGY. 



The apical wall or membrana vestibularis consists of a thin layer of 

 connective tissue bounded on one side by the mesenchymal epithelium 

 of the scala vestibuli, and on the other by the simple flattened ectodermal 

 epithelium of the cochlear duct. 



The basal wall or lamina spiralis extends from the modiolus per- 

 ipherally to the bony wall of the cochlea. Near the modiolus it lies between 

 the two scalae but peripherally it is between the ductus cochleae and the 

 scala tympani. Toward the modiolus it contains a plate of bone perforated 

 for the passage of vessels and nerves; this part is the lamina spiralis ossea. 

 The peripheral portion is the lamina spiralis membranacea.* Both parts 



Membrana tectoria. 



Capillaries of the stria. 



Hair cells. 



Labium vestibulare. Sulcus spiralis 



/ 



Hensen's Claudius's 

 cells. cells. }\-?-~ 



i fb\** 



4 i# 



J -b ' 



Nerve bundle. 



Labium Inner 

 tympanicum. 



Outer 



Deiters's Membrana Connective 



, cells. basilaris. tissue. 



Pillar cells. 

 FIG. 436. PORTION OF FIGURE 435. X 240. x, Intercellular "tunnel" traversed by nerve fibers. 



are covered below by the mesenchymal epithelium of the scala tympani, 

 and above by the epithelium of the cochlear duct including its complex 

 neuro-epithelium known as the spiral organ [of Corti]. 



Where the membrana vestibuli meets the osseous spiral lamina there is 

 an elevation of tough connective tissue called the limbus spiralis (Fig. 4^5 |. 

 It consists of abundant spindle-shaped cells and blends below with the 

 periosteum of the spiral lamina. Superficially ft produces irregularly hemi- 



* The familiar term lamina spiralis membranacea employed by Professor Stohr is not 

 included among the Nomina Anatomica. In place of it is lamina basilaris. Whether the 

 latter should be considered synonymous with the former, or should refer to the entire basal 

 layer into a portion of which a lamina spiralis ossea projects, is not apparent. 



