CHAPTER II. 



OLFACTORY NERVES OLFACTION. 



Nasal fossae Schneiderian and olfactory membrane Physiological anatomy of 

 the olfactory nerves Olfactory bulbs Olfactory cells and terminations of the 

 olfactory nerve-fibres Properties and functions of the olfactory nerves 

 Cases of anosmia in the human subject Mechanism of olfaction Relations 

 of olfaction to the sense of taste Reflex acts through the olfactory nerves. 



THE nerves directly connected with the senses of olfac- 

 tion, vision, and audition, are but slightly, if at all, endowed 

 with general sensibility. As regards the olfactory nerves, the 

 parts to which they are distributed are so fully supplied with 

 branches from the fifth, that it is difficult to determine the 

 fact of their sensibility or insensibility to ordinary impres- 

 sions. These nerves, however, are distributed to the mucous 

 membrane of that portion of the nasal cavity endowed with 

 the special sense of smell. Before taking up their physiolo- 

 gical anatomy, we shall describe briefly the parts to which the 

 olfactory sense is probably confined. 



Nasal Fossae. The two irregularly-shaped cavities in the 

 middle of the face, opening in front by the anterior nares 

 and connected with the pharynx by the posterior nares, are 

 called the nasal fossae. The membrane lining these cavities 

 is generally called the Schneiderian mucous membrane, 1 and 

 sometimes, particularly by the French, the pituitary mem- 



1 Some authors distinguish the olfactory membrane, lining the upper part of 

 the nasal fossse, from the rest, calling the membrane lining those parts not en- 

 dowed with the sense of smell, the Schneiderian membrane. (KOLLIKER, Hand- 

 buck der Gewebelehre, Leipzig, 1867, S. 741.) Most writers, however, apply the 

 term Schneiderian membrane to the general lining membrane of the fossae. 



