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SYMPATHETIC NERVES. 



THE Sympathetic system consists of a series of ganglia, extending 

 along each side of the vertebral column from the head to the coccyx, 

 communicating with all the other nerves of the body, and distributing 

 branches to all the internal organs and viscera. 



It communicates with the other nerves immediately at their exit 

 from the cranium and vertebral canal. The fourth and sixth nerves, 

 however, form an exception to this rule ; for with these it unites in the 

 cavernous sinus ; and with the olfactory, optic, and auditory, at their 

 ultimate expansions. 



The branches of distribution accompany the arteries which supply 

 the different organs, and form communications around them, which 

 are called plexuses, and take the name of the artery with which they 

 are associated: thus we have the mesenteric plexus, hepatic plexus, 

 splenic plexus, &c. All the internal organs of the head, neck, and 

 trunk are supplied with branches from the sympathetic, and some of 

 them exclusively ; hence it is considered a nerve of organic life. 



It is called the ganglionic nerve from the circumstance of being 

 formed by a number of ganglia ; and from the constant disposition 

 which it evinces in its distribution, to communicate and form small 

 knots or ganglia. 



There are five sympathetic ganglia in the head ; viz., the ganglion of 

 Ribes ; the ciliary or lenticular; the spheno-palatine, or Meckel's ; the 

 otic, or Arnold's^ and the submaxillary : three in the neck ; superior, 

 middle, and inferior: twelve in the dorsal region ; four in the lumbar 

 region ; and four or five in the sacral region. 



Each ganglion may be considered as a distinct centre giving off 

 branches in four different directions, viz., superior or ascending to 

 communicate with the ganglion above ; inferior or descending, to com- 

 municate with the ganglion below ; external to communicate with the 

 spinal nerves ; and internal, to communicate with the sympathetic 

 filaments of the opposite side, and to be distributed to the viscera. 



CRANIAL GANGLIA. 



Ganglion of Ribes, 

 Ciliary, or lenticular ganglion, 

 Spheno-palatine, or Meckel's ganglion, 

 Otic, or Arnold's ganglion, 

 Submaxillary ganglion. 



The GANGLION OF RIBES is a small ganglion situated upon the 

 anterior communicating artery, and formed by the union of the sympa- 

 thetic filaments, which accompany the ramifications of the two anterior 

 cerebral arteries. These filaments are derived from the carotid plexus, 

 at each side ; and through their intervention, the ganglion of Ribes is 



