EXAMINATION OF THE RESPIRATORY APPARATUS. 



313 



Inspection sometimes reveals deformity of the external wall of the 

 sinus. Such deformity, however, is rare, and Moussu has only 

 observed it in two cases of tuberculosis of the bones forming the 

 cranial wall. 



By percussion one detects abnormal sensibility, and partial or com- 

 plete dulness over certain areas. 



Maxillary sinus. — The maxillary sinus occupies the whole lateral 



Fig. 164. — General arrangement of the sinuses. The circular openings indicate 

 points at which trepanation is performed. 



region of the face, from the inferior extremity of the maxillary spine 

 as far as the sub-orbito-palatine region. In front its external wall 

 is very solid, but behind, below the orbit, is extremely thin. Ex- 

 ternally the sinus is largely protected by the anterior insertion of the 

 external masseter muscle, a fact which explains how rarely it is 

 injured. 



Larynx. In consequence of its deep situation, the larynx can 



