404 HEAD AND NECK 



pterygo-palatine or pharyngeal nerve). They are distributed 

 to the muco-periosteum of the posterior part of the roof of 

 the nasal cavity, to the adjacent parts of the wall of the 

 pharynx, to the sphenoidal air sinus, and to the pharyngeal 

 part of the auditory tube. 



The descending branches are the palatine nerves, and with 

 them are incorporated the posterior inferior nasal nerves. 

 The palatine nerves are three in number, anterior (O.T. great 

 or posterior palatine), middle, and posterior. As a rule these 

 spring by a common trunk from the lower aspect of the 

 ganglion. The trunk descends in the pterygo-palatine canal, 

 which has been opened up already, but to expose the 

 nerves a dense fibrous investment must also be removed. 

 The nerve-trunk will then be seen breaking up into its con- 

 stituent parts. 



Dissection. Trace, in the first instance, the two smaller nerves viz., 

 the middle and posterior palatine branches. These leave the main canal 

 and enter the small palatine canals, which conduct them through the 

 pyramidal process of the palate bone. Before opening these up it is well 

 to secure the nerves as they emerge from the lower openings of the canals. 

 This can very readily be done, by dissecting posterior to the hamulus of 

 the medial pterygoid lamina and gently separating the soft parts from 

 the under aspect of the pyramid of the palate bone. As the dissection 

 is being made from the inside, the middle palatine nerve will be first en- 

 countered, and it will be seen to pass posteriorly into the soft palate, 

 under cover of the tendinous expansion of the tensor veli palatini. 1 This 

 must be divided, in order that the nerve may be followed to its distribu- 

 tion. The posterior palatine nerve will be found issuing from its canal a 

 short distance to the lateral side of the preceding nerve. It is distributed 

 to the soft palate in the neighbourhood of the tonsil. It is smaller than 

 the middle palatine nerve, and is sometimes absent. The large anterior 

 palatine nerve should now be followed onwards to the hard palate. To 

 do this the lower part of the palatine canal must be opened up by removing 

 a small portion of the posterior and lateral part of the horizontal plate of 

 the palate bone. 



The anterior palatine nerve is the largest branch of the 

 spheno-palatine ganglion. It descends through the pterygo- 

 palatine canal, accompanied by the great palatine branch of 

 the internal maxillary artery ; it enters the palate through the 

 great palatine foramen and runs anteriorly, in a groove on the 

 lower aspect of the hard palate, towards the incisive foramen. 

 It supplies the gum, the mucous membrane, and the glands 

 of the vault of the mouth ; and, in the neighbourhood of the 

 incisive foramen, it communicates with the naso-palatine 



1 The present is a good opportunity to observe the corrugated or wrinkled 

 appearance of the tendon of the tensor palati, as it passes under the hamulus. 



