OLFACTORY NERVE. 



435 



The fourth, facial and eighth nerves were considered by Sir Charles 

 Bell to form a system apart from -the rest, and to be allied in the 

 functions of expression and respiration. In consonance with this 

 view he termed them respiratory nerves, and he gave to that part of 

 the medulla oblongata from which they arise the name of respiratory 

 tract. 



FIRST PAIR. OLFACTORY. The olfactory nerve arises by three 

 roots ; an inner root from the substantia perforata, a middle root from 



Fig. 143.* 



* 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. 1. The frontal sinus. 2. The 

 nasal bone. 3. The crista galli process of the ethmoid bone. 4. The sphenoi- 

 dal sinus of the left side. 5. The sella turcica. 6. The basilar process of the 

 sphenoid and occipital bones 7- The posterior opening of the right nares. 8. 

 The opening of the Eustachian tube in the upper part of the pharynx. 9- The 

 soft palate, divided through its middle. 10. Cut surface of the hard palate. 

 . The olfactory nerve, b. Its three roots of origin, c. Its bulb, from which 

 the filaments are seen proceeding which 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 external and internal branch, e. The naso-palatine nerve, 

 a branch of the spheno-palatine ganglion distributing twigs to the mucous 

 membrane of the septum nasi in its course to (f] the anterior palatine foramen, 

 where it forms a small gangliform swelling (Cloquet's ganglion) by its union 

 with its fellow of the opposite side. g. Branches of the naso-palatine nerve 

 to the palate, h. Posterior palatine nerves, i, i. The septum nasi. 



