THE MIDDLE EAR. 



427 



The ossicles of the tympanum are the malleus, incus, 

 and stapes. They constitute a chain of bones, which trans- 

 mit the vibrations of sound from the membrana tym- 

 pani to the internal ear. The malleus presents a head, 

 neck, and three processes. The head articulates with the 

 incus. The handle is the vertical process attached to the 

 membrana tympani. The processus gracilis gives attach- 

 ment to the laxator tympani muscle. It passes outward 

 nearly at right angles to the handle, and lies in the Glase- 



FIG. 186. I. THE MECHANICS OF THE AUDITORY OSSICLES. II. SECTION 

 OF THE MIDDLE EAR. 



I. a. malleus: h, incus: am. long process of incus; s, stapes : the arrows show the direc- 

 tion of motion. II. G, external auditory canal ; M. t., membrana tympani ; C, tympanum ; 

 H, malleus ; L S., superior ligament : S, stapes. 



rian fissure. The short process is a tubercle on the root 

 of the handle. It gives attachment to the tensor tympani. 

 The incus presents a body and two processes. The 

 body articulates with the malleus. The processes are : 

 the long and short, at right angles with one another. 

 The short process is attached to the posterior wall ; the 

 long process, parallel with the handle of the malleus, 

 terminates in the lenticular process, which articulates 

 with the head of the stapes. 



