INTERNAL EAR 



257 



is a narrow tube, the canalis reuniens, which runs from this duet 

 to the saccule — part of the organ for maintaining eciuihln-ium. 



The reason for the attention that has been directed to the scala 

 media is that the cochlear division of the auditory nerve, which runs 

 down the modiolus, enters only this scala, passing along the basilar 

 membrane and ending in dendrites among the hair-cells of the 

 organ of Corti. This structure is a development of the epithelium 

 lining the tube. It is set on the basilar membrane at its junction 

 with the limbus laminae spiralis, and consists of four essential 



Fig. 65. — Vertical section oi the first turn of the human cochlea (G. Retzius). 

 s.v, scala vestibuli ; s.t, scala tj'mpani ; D.C, scala media ; sp.l, spiral lamina ; n, nerve 

 fibres; /.sp, spiral ligament ; .s//-.c, stria vascularis ; ?K.f, membrana tectoria ; ft.;?;., basilar 

 membrane ; /;.;', and h.e, internal and external hair cells ; R, section of Keissner's membrane ; 

 t.C, tunnel of Corti ; Z, limbus laminae spiralis. 



elements. (1) Certain columnar cells with short stiff hair-like 

 processes projecting from their free border, the hair cells, to which 

 pass, as we have just said, branches of the cochlear nerve ; 



(2) elongated strengthening cells between the hair cells, cells of 

 Deiters, the peripheral processes of which join together to form a 

 network through which the hair-cells project {membrana reticularis) ; 



(3) stiff short fibres set one against another in the form of an arch ; 

 and (4) an exceedingly delicate membrane attached to the upper 

 surface of the spiral lamina, and lying over or fixed to both the 

 outer and the inner walls of Corti's organ {membrana tectoria). 



The arch of Corti, which lies just outside the single row of inner 



B. 17 



