Our Surroundings 



well adapted to catch and converge sound waves. It encloses the 

 auditory canal, or passage, which at its inner end is covered with 

 a membrane called the ear drum, or tympanic membrane. This 

 membrane receives the sound waves and transmits them through 

 the middle ear to the cochlea, the real organ of hearing. 



The middle ear is a small chamber in the bones of the head, 

 located at the inner end of the auditory canal and separated from 

 it by the ear drum. Immediately in contact with the ear drum 

 and connecting it with the inner ear is a chain of three small 

 bones which, because they resemble a hammer, an anvil, and a 

 stirrup, have been given these names. A passage, called the 

 Eustachian tube, connects the middle ear with the mouth and 

 thus protects the ear drum by equalizing the air pressures on its 

 two sides. For this reason, it is well to have the mouth open 

 during loud, sudden noises, such as explosions. 



In a bony cavity immediately beyond the middle ear lies the 

 inner ear, consisting of two parts, the semi-circular canal, and 

 the cochlea, a spiral tube full of liquid which transmits sound. 

 Sound waves set the ear drum vibrating and this movement is 

 carried through the three bones of the middle ear to the cochlea, 

 through the liquid in the cochlea to delicate nerve cells on its 

 inner surface, and from them through the auditory nerve to the 

 brain. 



Precautions for the care of the ears. 



1. Keep the ear openings clean and dry. 



2. Do not try to remove ear wax with a pin on other hard 

 instrument. 



3. In case a seed or other foreign body gets into the ear, 

 have a doctor remove it. An insect can usually be removed with- 

 out difficulty by the use of water or sweet oil. 



4. In case of very loud noises, open the mouth so as to 

 equalize the air pressure on the ear drums. 



5. Do not blow the nose too violently, since disease germs 

 may be driven through the Eustachian tube into the middle ear 

 and cause serious infection. 



6. In case of earache make outside heat applications hot 

 water bags or heated flannel. 



