DETERMINING THE STATUS PRAESEXS. 27 



J Occurrence of the Different Qualities of Percussion- 

 Sounds. 



According to the above classification there are three kinds 

 of percussion-sounds: The full (pulmonary resonant), the 

 tympanitic, and the flat. 



1. The full sound is found over normal lung, the air in 

 the alveoli, and the lung tissue, and thoracic walls vibrating. 

 When the intestines are so distended with gas that when per- 

 cussed their walls vibrate with their contents, a full sound is 

 emitted. 



2. The tympanitic percussion-sound has a varied origin. 

 It is heard : 



a. Over cavities containing air which communicate with 

 the outside world, their walls being either firm or yielding : 

 trachea, caverns in the lung communicating with bronchi. The 

 pitch of the sound depends upon the size of the cavern and its 

 communicating opening. 



b. Over enclosed air-containing cavities, hence over the 

 stomach and bowels. 



c. When air-containing lung tissue is surrounded by 

 solidified portions as occurs in beginning hepatization, edema, 

 atelectasis and tumors of the lung. 



3. The flat (femoral, dull) sound is heard when percuss- 

 ing over solid tissues which do not contain air. As the most 

 forcible percussion does not produce vibrations at a point more 

 than 7 cm below the surface, dullness can be noted over the 

 normal lung when the chest walls are covered with heavy 

 muscles, fat, or edematous swellings. 



An over-loud sound is emitted when the base of the 

 cecum in the horse or the paunch in the ox is percussed, these 

 organs being greatly distended with gas. 



The sound is dulled when air-containing parts of limited 

 'dimensions are percussed (borders of the lung, and under 



