430 



PRACTICAL ANATOMY. 



of the auditory nerve to the cochlea ; it terminates in 

 the apex of the cochlea (called the cupola) in a funnel- 



T . shaped dila- 

 tation, defi- 

 cient at one 

 side. The 

 spiral canal 

 of the coch- 

 lea is about 

 one and a 

 half inches 

 long, de- 

 creases in 

 size as it 

 ascends, and 



terminates in the rounded 

 apex, the cupola. It 



Cc 



is about one-tenth inch 

 diameter, and pre- 



111 



sents at its commence- 

 ment: 1. the fenestra 

 rotunda, which commu- 

 nicates with the tympa- 

 num. 2. The foramen 

 ovale, which communi- 

 cates with the vestibule. 

 3. The opening of the 

 aquaeductus cochlea. 



The spiral canal is 

 divided by an osseo- 

 membranous partition 

 into an upper canal, the scala vestibuli, and a lower 

 canal, the scala tympani. Along the circumference 

 of the lower portion of the scala vestibuli is the scala 



FIG. 188. SCHEME OF THE LABYRINTH 

 AND TERMINATION OF THE AUDITORY 

 NERVE. 



I. Transverse section of a turn of the cochlea. II. 

 A, ampulla of a semicircular canal ; a, p, auditory cells ; 

 p. provided with a fine hair; T, otoliths. III. Scheme 

 of the human labyrinth. IV. Scheme of a bird's laby- 

 rinth. V. Scheme of a fish's labyrinth. 



