THE HEAD AND NECK 



»«59 



stated, with the deep poles of the olfactory cells. The olfactory 

 nerves are destitute of a medullary sheath. 



Nerves of Ordinary Sensation. — These axe derived from the ophthalmic and 

 superior maxillary divisions of the fifth creinial nerve, and are as follows : 



1. Superior nasal nerves. 



2. Nasal branches of the Vidian 



nerve. 



■I. Inferior nasal nerves. 



4. Internal branches of the nasal 



nerve. 



5. Nasal branch of the anterior 



superior dental nerve. 



6. Naso-palatine nerve. 



The superior nasal nerves are derived from Meckel's ganglion. They enter 

 the superior meatus through the spheno-palatine foramen, and are distributed 

 to the mucous membrane (i) over the superior and middle conchae, (2) over 

 the upper and back part of the septum nasi, and {3) within the posterior 

 ethmoidal cells. 



The nasal branches of the Vidian nerve pierce the floor of the pterygoid or 

 Vidian canal, and are distributed to the mucous membrane over the back 

 part of the roof of the nasal fossa and the adjacent part of the septum. 



Posterior Ethmoidal Artery 

 Spheno- Palatine Artery y 



AnteriOT EthnKudal Artery 



Soft Palate 



Fig. 517. — The Arteries of the Nasal Septum (Hirschfeld and 



Leveille). 



The inferior nasal nerves arise from the great or anterior descending pala- 

 tine branch of Meckel's ganglion, as that nerve traverses the posterior pala- 

 tine canal. They enter the nasal fossa through foramina in the vertical plate 

 of the palate bone, and are distributed to the mucous membrane over the 

 greater part of the inferior concha, and the corresponding parts of the middle 

 and inferior meatus. 



The internal branches of the nasal nerve are two in number, septal and 

 external. The septal branch is distributed to the mucous membrane over 

 the anterior and upper part of the septum, and the external branch to that 

 over the anterior portions of the middle and inferior conchae, and over the 

 Outer wall in front of these. 



The nasal branch of the anterior superior dental nerve is distributed to the 

 mucous membrane over the anterior part of the inferior meatus and the 

 adjacent part of the floor of the nasal fossa. 



