THE SENSES. 177 



to it. Air impregnated with the vapor of camphor was injected into the 

 frontal sinus through a fistulous opening, and odorous substances have 

 been injected into the antrum of Highmore; but in neither case was any 

 odor perceived by the patient. The purposes of these sinuses appear to 

 be, that the bones, necessarily large for the action of the muscles and other 

 parts connected with them, may be as light as possible, and that there 

 may be more room for the resonance of the air in vocalizing. The former 



FIG. 355. Nerves of the outer walls of the nasal fossae. 3-5. 1, network of the branches of the 

 olfactory nerve, descending upon the region of the superior and middle turbinated bones; 2, external 

 twig of the ethmoidal branch of the nasal nerves ; 3, spheno-palatine ganglion ; 4, ramification of the 

 anterior palatine nerves; 5, posterior, and 6, middle divisions of the palatine nerves; 7, branch to the 

 region of the inferior turbinated bone; 8, branch to the region of the superior and middle turbinated 

 bones; 9, naso-palatine branch to the septum cut short. (From Sappey, after Hirschfeld and 

 Leveille.) 



purpose, which is in other bones obtained by filling their cavities with 

 fat, is here attained, as it is in many bones of birds, by their being filled 

 with air. 



Other Functions of the Olfactory Region. All parts of the nasal 

 cavities, whether or not they can be the seat of the sense of smell, are 

 endowed with common sensibility by the nasal branches of the first and 

 second divisions of the fifth nerve. Hence the sensations of cold, heat, 

 itching, tickling, and pain; and the sensation of tension or pressure in the 

 nostrils. That these nerves cannot perform the function of the olfactory 

 nerves is proved by cases in which the sense of smell is lost, while the mu- 

 cous membrane of the nose remains susceptible of the various modifications 

 of common sensation or touch. But it is often difficult to distinguish the 

 sensation of smell from that of mere feeling, and to ascertain what belongs 

 to each separately. This is the case particularly with the sensations, 

 excited in the nose by acrid vapors, as of ammonia, horse-radish, mustard r 

 etc., which resemble much the sensations of the nerves of touchj and the- 

 difficulty is the greater, when it is remembered that these acrid vapors 

 VOL. II. 12. 



