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pharynx. There are two other openings in the bony wall of 

 the cavity of the middle ear, but both of these are closed by 

 membranes ; one is oval and called the fenestra ovalis, and 

 the other is round and called the fenestra rotunda. They 

 lead to the internal ear. Stretching across the cavity of the 

 middle ear from the tympanic membrane to the fenestra ovalis 

 is a chain formed by three very delicate bones. These are the 

 auditory ossicles. 



The first of these is somewhat hammer-shaped, and is called 



FIG. 103. The parts of the car. 



Co, external ear: R. i\f, external auditory canal': '/>.,!/, tympanic membrane ; Inc. 

 Mall, Incus malleus ; A.S.C, f.S.C, E.S.C, the three semicircular canals; 

 Coc, cochlea; En, Eustachiau lube; /..I/, canal through which the auditory 

 nerve rcaclio the internal car. 



the malleus. The part like the handle of the hammer is 

 attached vertically to the inner side of the tympanic membrane, 

 and the rounded head of the hammer articulates with the 

 second bone, the incus or anvil bone. The malleus has also 

 a short, slender process attached by a ligament to the bony 

 wall of the middle ear. The incus has a broad concave head, 

 into which the head of the malleus fits, and two processes ; 

 the shorter process is attached to the wall of the middle ear by 



