SPHENO-PALATINE GANGLION. 435 



receives also a filament of communication (middle root) from the spheno- 

 palatine ganglion ; and it sometimes sends a twig to the abducens nerve. 



The SPHENO-PALATINE GANGLION (MeckePs) the largest of the cranial 

 ganglia of the sympathetic, is very variable in its dimensions. It is 

 situated in the spheno-maxillary fossa. 



Its branches are divisible into four groups ; ascending, descending, in- 

 ternal, and posterior. 



The branches of distribution are the internal and the descending. The 

 internal -branches are the nasal and the naso-palatine. The nasal or 

 spheno-palatine nerves, four or five in number, enter the nasal fossa through 

 the spheno-palatine foramen, and are distributed to the mucous membrane 

 of the superior meatus, and superior and middle spongy bones. Besides 

 these, several branches issue through small openings in the palate and 

 sphenoid bone, and supply the mucous membrane of the upper part of the 

 pharynx and the Eustachian tube. 



The naso-palatine nerve (Scarpa) enters the nasal fossa with the nasal 

 nerves, and crosses the roof of the nares to reach the septum, to which it 

 gives several filaments. It then curves downwards and forwards to the 

 naso-palatine canal, and enters the anterior palatine canal, where it joins 

 with its fellow of the opposite side, and receives filaments from the ante- 

 rior dental and palatine nerves. By this junction an enlargement is 

 formed^the naso-palatine ganglion (Cloquet's), which distributes filaments 

 to the mucous membrane of the palate, immediately behind the incisor 

 teeth. 



The descending branches are the three palatine nerves, anterior, middle, 

 and posterior. 



The anterior palatine nerve, the largest of the three, descends from the 

 ganglion through the posterior palatine canal, and emerges at the posterior 

 palatine foramen. It then passes forwards in the substance of the hard 

 palate to which it is distributed, and communicates with the naso-palatine 

 ganglion and with its branches. While in the posterior palatine canal this 

 nerve gives off several branches, which enter the nose through openings 

 in the palate bone, and are distributed to the middle and inferior meatus, 

 the inferior spongy bone, and the antrum. 



The middle palatine nerve descends through the same canal to the pos- 

 terior palatine foramen, and distributes branches to the tonsil, soft palate, 

 and uvula. 



The posterior palatine nerve, the smallest of the three, quits the other 

 nerves to enter a distinct canal, from which it emerges by a separate open- 

 ing behind the posterior palatine foramen. It is distributed to the hard 

 palate and gums near the point of its emergence, and to the tonsil and 

 soft palate. 



^ The branches of communication are the ascending and the posterior. 

 The ascending branches are, one or two to join the superior maxillary 

 nerve; one to the abducens nerve; one to the ciliary ganglion constituting 

 its middle root ; and occasionally two filaments to *he optic nerve within 

 the orbit. The posterior branch is the Vidian or pieiygoid nerve. 



The Vidian* nerve passes directly backwards from xhe spheno-palatine 



* Guido Guidi, latinized into Vidus Vidius, was professor of anatomy and medicine 

 in the College of France in 1542. His work is posthumous, and -vas published m 



