THE EAR, HEARING, TASTE AND SMELL 189 



between the mucous membrane lining the inside of the drum 



membrane and the membrane proper, and is firmly attached to 



the latter near its center and keeps the membrane dragged in 



there so as to give it its peculiar 



concave form, as seen from the 



outside. The incus has a body 



and two processes, and is much 



like a molar tooth with two fangs. 



On its body is an articular hollow 



to receive the head of the malleus ; 



its short process (/&) is attached by 



ligament to the back wall of the 



tympanum; the long process (JZ) 



is directed inwards to the stapes; 



On the tip of this process is a little .. Fip. 70. The auditory ossicles of 



r the right ear, seen from the front. M, 



knob, which represents a bone (OS malleus; J, incus; S, stapes; Mcp, 



j. 7 \ i j. i i'f head of the malleus ; Me, neck of 



OrOlCUlare) distinct in early life, ditto -Ml, long process; Mm, handle; 



<?tnnoej (K} i p-v-tromplv liko a Jc ' bod y> Jb > short, and Jl, long 



' a process of incus; J'pl, os orbiculare; 



stirrup, and its base (the footpiece SC P> head of stapes. 

 of the stirrup) fits into the oval foramen, to the margin of which 

 its edge is united by a fibrous membrane, allowing of a little play 

 in and out. 



From the posterior side of the neck of the malleus a ligament 

 passes to the back wall of the middle ear: this, with the ligament 

 imbedding the slender process and fixed to the front wall of the 

 cavity, forms an anteroposterior axial ligament, on which the 

 malleus can slightly rotate, so that the handle can be pushed in 

 and the head out and vice versa. If a pin be driven through 

 Fig. 70 just below the neck of the malleus and perpendicular to 

 the paper it will very fairly represent this axis of rotation. Con- 

 nected with the malleus is a tiny muscle, called the tensor tympani; 

 it is inserted on the handle of the bone below the axis of rotation, 

 and when it contracts pulls the handle in and tightens the drum 

 membrane. Another muscle (the stapedius) is inserted into the 

 outer end of the stapes, and when it contracts fixes the bone so 

 as to limit its range of movement in and out of the fenestra ovalis. 



The Internal Ear. The labyrinth consists primarily of cham- 

 bers and tubes hollowed out in the temporal bone and inclosed 

 by it on all sides, except for the oval and round foramina on its 



