CHAPTER XVII. 



SPECIAL SENSES (Continued.) 



THE SENSE OF SMELL. 



THE seat of the sense of smell resides in the cavities of the nose. 

 Kant has very aptly spoken of smell as "taste at a distance." 



The organ of smell resembles those of sight and hearing in that 

 it consists of a special nerve which ends in a specialized epithelium. 

 In this case the special nerve is the olfactory ; the specialized epithe- 

 lium is the mucous membrane of the upper portion of the nasal 

 cavity. It is in this portion the mucous membrane that the fila- 



Fig. 303. Innervation of the External Wall of the Nasal Fossa. 



(TESTUT.) 



1, Olfactory tract. 2, Olfactory bulb. 3, Branches of olfactory nerve. 5, 

 Ganglion of Meckel. 6, Pharyngeal nerve. 7, Vidian nerve. 8, 9, Spheno- 

 palatine. 10, 11, 12, 12', Palatine nerves with, 13, nasal branch. 14, 14', Termina- 

 tion of ethmoidal nerve. 15, Opening of Eustachian tube. 16, Vault of palate. 



ments of the olfactory nerve are distributed. For that reason it has 

 been termed the regio olfactoria, and comprises the upper portion of 

 the septum, the upper turbinated, and part of the middle turbinated 

 regions. All other portions of the nasal-cavity covering is known as 

 the regio respiratoria, or simply the Schneiderian membrane. During 

 ordinary respiration the currents of air in their passage in and out 

 (742) 



