320 ELEMENTS OF HISTOLOGY. [Chap. xu. 



merits of the bones are, like other ligaments, made up 

 of straight and parallel bundles of fibrous connective 

 tissue. The articulation surface of the head of the 

 malleus, of the incus, of the extremity of the long 

 process of the incus, and of the stapes, are covered 

 with hyaline (articular) cartilage. 



CHAPTER XLI. 



THE INTERNAL EAR. 



458. THE osseous labyrinth consists of the vesti- 

 bule, prolonged on one side into the cochlea, and on 

 the other into the three semicircular canals, each of 

 which possesses an ampulla at one extremity. The 

 vestibule shows two divisions the fovea hemispherica 

 next to the cochlea, and the fovea hemielliptica next 

 to the semicircular canals. The cochlea consists of 

 two and half turnings twisted round a bony axis the 

 modiolus. From this a bony lamina extends towards 

 the outer wall for each turn, but does not reach it : 

 this is the lamina spiralis ossea. It extends through 

 all turns, and it subdivides the cavity of each turn 

 into an upper passage, or scala vestibuli, and a lower, 

 or scala tympani. At the top of the cochlea the two 

 scalae pass into one another by the helicotrema. The 

 scala vestibuli opens into the fovea hemispherica, 

 while the scala tympani at its commencement i.e., 

 at the proximal end of the first turn would be in 

 communication, by the fenestra rotunda, with the 

 cavum tympani, were it not that this fenestra rotunda 

 is closed by a membrane the secondary membrane. 



459. The semicircular canals start from, and return 

 to, the fovea hemielliptica of the vestibule. 



The fenestra ovalis leads from the cavum tympani 

 into the vestibule its hemispheric division ; and this 



