PHYSIOLOGY FOR BEGINNERS 



a ligament, while the longer process articulates with the third 

 bone, the stapes or stirrup bone. The stapes, which is exactly 

 like a stirrup, lies nearly horizontally ; the top of the arch of 

 the stirrup is attached to the incus, and the foot-plate of the 

 stirrup fits into the fenestra ovalis, and is attached to the 

 membrane covering it. Two small muscles pass from the 

 wall of the cavity to the ossicles : one is attached to the 

 handle of the malleus, and its action tightens the tympanic 



FIG. 104.- Diagram of the auditory ossicles and the parts of the internal ear. 

 E.M, external auditory canal ; Ty.M, tympanic membrane ; Ty, middle ear 

 cavity; Mail, malleus; Inc, incus; Sip, stapes; /'.<?, fenestra ovalis; F.r, 

 fenestra rotunda ; En, Eustachian tube; M.L, membraneous labyrinth, one 

 semicircular canal represented; Sca.M, canal of the cochlea; Sca.V, the part 

 of the cavity of the cochlea above the canal of the cochlea ; Sea. T., the part 

 below. 



membrane ; the other is attached to the arch of the stapes, 

 and its action tightens the membrane closing the fenestra 

 ovalis. 



The Internal Ear. The essential part of the organ of 

 hearing that in which the auditory nerve ends consists of a 

 membrane in the form of a closed bag, consisting of different 

 parts, each of a peculiar and complicated form. The mem- 

 braneous bag, with its different parts, lies in a cavity of 



