XIX. 



THE EAR AND HEARING. 



A. The Ear. 



Material. The ear of some animal, as a dog, or a large model of 

 the human ear. 



Study a large model of the human ear. 



Note: 



I. THE EXTERNAL EAR. 



a. The concha, or expansion on the outside of the head. 



b. The passage leading into the head, or external auditory 

 meatus. 



c. The drum, or tympanic membrane at the inner end of 

 the passage. 



II. THE TYMPANUM, OR MIDDLE EAR. 



a. The Eustachian tube leads from the middle ear to the 

 pharynx. What is its use ? 



b. The three bones of the ear. 



1. The malleus, or hammer, is in contact with the 



drum. 



2. The incus, or anvil-bone, rests against the malleus. 

 * 3. The stapes, or stirrup-bone, is the innermost bone. 



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