NASAL CAVITIES 401 



Nerves and Vessels on the Lateral Wall of the Nasal 

 Cavity : 



Nerves of Smell, . Olfactory nerves. 



fi. Lateral nasal branches of anterior ethmoidal. 



I 2. Nasal branch of anterior superior alveolar. 

 13- 



Nerves of Common! 3. Posterior superior nasal branches from spheno- 

 Sensation, . .1 palatine ganglion and from the nerve of the 



pterygoid canal. 



^4. Two posterior inferior nasal branches from the 

 anterior palatine nerve. 



The olfactory nerves are from twelve to twenty fine filaments 

 which spring from the lower surface and the extremity of the 

 olfactory bulb, and, passing through the apertures in the cribri- 

 form plate of the ethmoid into the nasal cavity, they separate 

 into a lateral and a medial group. To each nerve an invest- 

 ment from the cerebral membranes is given. The medial or 

 septal nerves were described on p. 392. The lateral nerves 

 descend in the muco-periosteum on the lateral wall of the nasal 

 cavity. At first lodged in shallow grooves or minute bony 

 canals, they soon divide into bunches of branches which spread 

 out over the upper concha and the region immediately below. 

 The dissection of these nerves is exceedingly difficult, but in 

 a well-preserved part they can generally be partially displayed. 



The posterior superior nasal nerves^ which come from the 

 spheno-palatine ganglion and from the nerve of the pterygoid 

 canal, are minute filaments, but the dissector should nevertheless 

 endeavour to trace them to their distribution upon the lateral 

 wall. They enter the nose through the spheno-palatine foramen, 

 which is situated at the posterior end of the superior meatus. 



The best plan to adopt for their display is to trace the largest of the 

 group, the naso- palatine nerve, which has already been exposed on the nasal 

 septum, laterally across the roof of the nasal cavity. This will lead the 

 dissector to the foramen, and by carefully dissecting the muco-periosteum 

 in its neighbourhood the other nerves of the group may be detected as they 

 enter the nasal cavity. 



They are distributed to the muco-periosteum over the upper 

 and middle conchse, and the posterior part of the septum. 



The inferior nasal nerves are two in number ; they both 

 arise from the anterior palatine nerve. 



Make a vertical incision, through the muco-periosteum over the posterior 

 part of the medial pterygoid lamina, and carefully raise the membrane 

 from the posterior part of the lateral wall of the nasal cavity. 



The upper of the two inferior nasal nerves will be found 

 emerging through a small aperture in the perpendicular part 

 VOL. II 26 



