THE EAR. 



363 



The scala tympani is a blind canal, having at one extremity 

 the membrane which covers the fenestra rotunda, and at the 

 upper part terminating in. the cupula of the cochlea, where it 



Lsp 



PlO. 162. Section of the cochlea of a human embryo at the fourth month, a. a, a, cartilaginoo* 

 incaoement of the cochlea; 6. fr, perichondrium ; c, mncuid tissue matrix of the modiolug; d, d, cartila- 

 ginous septa of the individual turns of the cochlea ; e 4 , sections of the ductus cochleariR ; /, /,. Reiss- 

 ner's membrane ; g, membrana tectoria. eomewlint lifted up from the subjacent parts ; A, rudiment of the 

 stria Tascularis ; <, rudiment of the subsequent organ of Corti ; L up, lamina spiralis ; Ol, Of,, ganglion 

 spirale with variono efferent and afferent bundles of nerves; ST, scala tympani; SV, scala vest.ibuli; 

 AT,, (SK,, ST t , miiccid tissue where later the scala; of the last cochleal turn will be. i 1 -'. Waldeyer. 



is said to enter into communication with the scala vestibuli 

 by a minute opening, the helicotrema. 



The scala vestibuli stands in direct communication with the 

 perilymphatic space of the vestibular sacs, while the ductus 

 cochlearis is in communication with the saccule by means of 

 a slender canal (the canalis reuniens). The walls of the two 

 scalse are formed of a thin periosteum, on the surface of which 



