ORGAN OF SMELL. 



150 



membrane is the seat 

 of the secretion of 

 nasal mucus, which, 

 doubtless, performs a 

 part in olfaction as im- 

 portant as the secretion 

 from the mucous mem- 

 brane of the mouth 

 does in gustation. 



The same nerve is 

 not distributed over 

 the whole of this mem- 

 brane. In some 

 parts, the olfactory, 

 ethmoidal, or' first 

 pair can be traced ; in 

 others, we see only 

 filaments of the fifth 

 pair. The first of 

 these have not always 

 been regarded as the 

 nerves of smell. An- 

 ciently, 



to be 



Fig. 59. 



View of the Olfactory Nerve, with its Distribution on the Septum 

 Nasi. The nares have been divided by a longitudinal section 

 made immediately to the left of the septum, the right nares 

 being preserved entire. 



tuita or phlegm, which 

 was supposed to be se- 

 creted by the brain. 



ful 



1. The frontal sinus. 2. The nasal bone. 3. The crista galli pro- 

 n p cess of the ethmoid bone. 4. The sphenoidal sinus of the left sido. 

 5. The sella turcica. 6. The basilar process of the sphenoid and occi* 

 pital bones. 7. The posterior opening of the right nares. 8. The 

 _% . opening of the Eustachian tube in the upper part of the pharynx. 9. 



for the passage Of pi- The soft palate, divided through its middle. 10. Cut surface of the 

 hard palate, a. The olfactory peduncle, b. Its three roots of origin. 

 c. Olfactory ganglion, from which the filaments proceed that spread 

 out in the substance of the pituitary membrane, d . The nasal nerve, 

 a branch of the ophthalmic nerve, descending into the left nares from 

 the anterior foramen of the cribriform plate, and dividing into its ex- 



. ternal and internal branch, e. The naso-palatine nerve, a branch of 



At the present Clay, the spheno-palatine ganglion distributing twigs to the mucous rnem- 

 c\ } f brane of the septum nasi in its course to (/) the anterior palatine fora- 

 LOE- men, where it forms a small gangliform swelling (Cloquet's ganglion) 



Onlv aS regards by its union with its fellow of the opposite side. g-. Branches of the 

 f , . & naso-palatine nerve to the palate, h. Posterior palatine nerves, i, i. 



their origin; some de- The septum nasi. 

 riving them from the 



anterior lobes of the brain; others from the corpora striata, which 

 have, in consequence, been called thalami nervorum ethmo'idalium; 

 and others, again, with Willis and Gall, 1 and with probability, referring 

 them, like every other nerve of sense, to the medulla oblongata. M. 

 B^clard affirms, that in a hydrocephalic patient, where a part of the 

 brain had been destroyed by disease, he actually saw this origin. 2 The 

 nerve proceeds directly forwards until it reaches the upper surface of 

 the cribriform plate of the ethmoid bone, where it divides into a number 

 of filaments, that pass through the foramina in the plate, and attain the 

 nasal fossae; where they are dispersed on the upper and middle part of 

 the Schneiderian membrane; but cannot be traced on the lower. Most 

 anatomists are of opinion, that here they constitute, with vessels of 

 exhalation and absorption, the papillae; whilst others, as Scarpa, not 

 having been able to trace them thither, have been of opinion, that the 

 filaments interlace to constitute a kind of proper membrane. Our 



1 Recherches snr le Systeme Nerveux en general et stir celui du Cerveau en particulier, 

 par F. J. Gall et G. Spurzheim, Paris, 1809. 



a Adelon, Physiologic de THomme, edit, cit., i. 330. 



