SPHENO-PALATINE GANGLION 405 



nerve. As it passes down the pterygo- palatine canal the 

 posterior inferior nasal branches, which were enclosed in 

 its sheath, leave it and enter the nasal cavity (p. 401). 



In tracing the anterior palatine nerve in the palate, 

 the dissector should note the numerous glands which are 

 placed under the mucous membrane of the vault of the 

 mouth, and the manner in which these indent the bone. 1 



Dissection. Considerable difficulty will be experienced in exposing the 

 nerves in the pharyngeal and pterygoid canals, which are very inaccessible. 



To open up -the pharyngeal canal the sphenoidal process of the 

 palate bone must be cautiously removed with the bone forceps, and then 

 the dissector should proceed to open up the pterygoid canal (O.T. Vidian), 

 which traverses the root of the pterygoid process. As the bone is very 

 hard and brittle at this point, the dissection must be effected very carefully. 



The nerve of the pharyngeal canal belongs to the posterior 

 superior nasal group (p. 403). 



Nervus Canalis Pterygoidei (O.T. Vidian}. The nerve 

 of the pterygoid canal is formed by a junction between the 

 great superficial petrosal branch of the facial and the great 

 deep petrosal branch of the carotid plexus. It traverses the 

 pterygoid canal, and joins the posterior aspect of the spheno- 

 palatine ganglion, of which it may be considered to repre- 

 sent both the motor and sympathetic root. In the canal it 

 is invested by a strong fibrous envelope, and when this is 

 removed it may sometimes be noticed to break up into a 

 fine plexus which surrounds the accompanying artery. It 

 has already been seen to give some fine filaments to the 

 muco-periosteum of the nose. 



The Rami Orbitales. The orbital branches of the ganglion 

 are exceedingly minute ; they pass anteriorly through the 

 inferior orbital fissure to supply the periosteum of the orbit. 



Termination of Internal Maxillary Artery. The internal 

 maxillary artery breaks up into its terminal branches in the 

 pterygo-palatine fossa. They are 



1. Posterior superior alveolar (p. 271). 



2. The infra-orbital (p. 388). 



3. The descending palatine. 



4. The spheno-palatine. 



The Descending Palatine Artery. The descending palatine 



1 An equally good method of tracing the anterior palatine nerve is to 

 remove the palatal processes of the palate and maxilla with the bone 

 forceps, and then to display the nerve and artery on the upper surfaces of 

 the mucous membrane and glands. 



