482 SPHENO-PALATINE GANGLION. 



flattened ganglion situated within the orbit, between the optic nerve 

 and the external rectus muscle ; it is in close contact with the optic 

 nerve, and is surrounded by adipose tissue, which renders its dissection 

 somewhat difficult. 



Its branches of distribution are the ciliary, which arise from its an- 

 terior angles by two groups : the upper group, consisting of about four 

 filaments ; and the lower, of five or six. They accompany the ciliary 

 arteries in a waving course, and divide into a number of filaments 

 which pierce the sclerotic around the optic nerve, and supply the tu- 

 nics of the eye-ball. A small filament is said by Tiedemann, to ac- 

 company the arteria centralis retinae into the centre of the globe of the 

 eye. 



Its branches of communication are three, one, the long root, which 

 proceeds from the posterior superior angle to the nasal branch of the 

 ophthalmic nerve ; a short thick branch, the short root, from the poste- 

 rior inferior angle to the inferior division of the third nerve ; and a 

 slender filament, the sympathetic root, which passes backwards to the 

 cavernous sinus, and communicates with the carotid plexus. Occa- 

 sionally the ciliary ganglion receives also a filament of communication 

 (middle root) from the spheno-palatine ganglion; and it sometimes 

 sends a twig to the abducens nerve. 



The SPHKNO-PALATINE GANGLION (Meckel's) 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, 

 internal, 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 anterior dental and palatine nerves. By this junction an enlarge- 

 ment is formed, the naso-palatine ganglion (Cloquefs), which distri- 

 butes filaments to the mucous membrane of the palate, immediately 

 behind the incisor teeth. 



The descending brandies 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 



