126 THE MEMBRANOUS LABYRINTH, BY PROF. RUDINGER. 



towards the tympanic cavity, so that the surfaces of contact are 

 somewhat smaller than at the already described anterior and 

 posterior extremities. A cartilaginous investment is, however, 

 here also present, which augments in thickness to some extent 

 towards the middle of the vestibular surface of the basis. The 

 connection with the cartilaginous investment of the margin 

 of the fenestra ovalis is established by means of a layer of 



Fig. 318. 



Fig. 318. Horizontal section through the anterior margin of the 

 base of the stapes at its attachment to the fenestra ovalis. 1, acute 

 angle made by the margin of the basis with the cartilage ; 2, base of 

 the stapes ; 3, anterior crus ; 4, margin of the fenestra ovalis invested 

 by hyaline cartilage ; 5, ligamentum baseos stapedis tympanicum ; 

 6, ligamentum baseos stapedis vestibulare ; 7, elastic fibrous layer of 

 the fenestra ovalis ; 8, the same at the base of the stapes ; 9, lacunar 

 system in the centre of the fibrous layer. The two ligaments at the 

 base of the stapes are not so sharply defined in the preparations 

 themselves as in the figure. 



elastic fibres, in the middle of which intercommunicating spaces 

 occur, though more sparingly than in that of the anterior and 

 posterior margin. 



The articulation of the stapes with the fenestra ovalis is 

 consequently neither a pure syndesmosis nor a synch ondrosis, 

 but constitutes a mode of connection that, if rightly placed in 

 the category of the other joints, would be included in the am- 

 phiarthroses, from which it differs only in the circumstance 



