762 



THE EAK. 



which is continued downwards from the saccule of the vestibule like the 

 neck of a flask, and enters the membranous canal abruptly nearly at a right 

 angle to it. Thus the cavity of the canalis membranacea is rendered con- 

 tinuous with that of the saccule. 



Fig. 519. THE LEFT LABYRINTH OF 

 A CHILD AT BIRTH, PARTIALLY 

 OPENED ON ITS OUTER SIDE TO SHOW 

 THE COMMENCEMENT OF THE MEM- 

 BRANOUS CANAL OF THE COCHLEA 

 (slightly altered after Reich ert). f 



The external or horizontal canal has 

 been removed; cs, superior canal; cp, 

 posterior canal ; a s, membranous am- 

 pulla and tube of the superior canal 

 cut short ; a 7i, that of the external or 

 horizontal canal ; h, undilated end of 

 the horizontal canal in front of the 

 common opening of the superior and 

 posterior canals ; p s, united superior 

 and posterior canals ; u, utriculus ; s, eacculus ; c c, vestibular part or commencement 

 of the membranous canal of the cochlea ; c r canalis reuniens connecting it with the 

 sacculus ; c, cochlea. 



It is necessary to explain that, although the canalis membranacea was described by 

 Reissner so long ago as in 1851, yet, owing to some confusion having arisen between 

 the membrane of .Reissner and the membrana tectoria described by Corti, whose 

 work appeared at the same time, the nature of this canal has until comparatively 



Fig. 520. DISTRIBUTION 

 OF THE COCHLEAR 

 NERVES IN THE LAMINA 

 SPIRALIS (after Henle). 



A, part of the modiolus 

 and spiral lamina showing 

 the cochlear nerves form- 

 ing a network, viewed from 

 the base ; 1, the twigs of 

 the nerve issuing frem the 

 tractus spiralis foramino- 

 sus ; 2, the branches of 

 the nerve entering by the 

 central canal of the modi- 

 olus ; 3, wide plexus in 

 the bony lamina spiralis ; 

 4, close plexus at its 

 border ; 1 1, labium tym- 

 pauicum; zi, zona interna ; 

 z e, zona externa ; 1 8 p, 

 ligamentum spirale. 13, 

 part of the nerves ex- 

 tracted and more highly 

 magnified ; 2, twigs of the 

 nerve from the modiolus 

 close to the lamina spiralis 

 ossea ; y s, spiral gangli- 

 form enlargement of the 

 nerve (habenaria gan- 

 glionaris) ; f s, nerve-fibres 



running spirally along the gangliforra swelling (Henle) ; 3, wide plexus ; 4, close plexus 



of nerve -fibres as in A. 



