CRANIAL GANGLIA. 425 



SYMPATHETIC SYSTEM. 



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 distribu- 

 ting 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 six sympathetic ganglia in the head: viz., the ganglion 

 of Ribes ; the ciliary or lenticular ; the naso-palatine, or Cloquet's ; 

 the spheno-palatine, or Meckel's ; the submaxillary; and the otic, or 

 Arnold's : 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 

 communicate with the ganglion below; external to communicate 

 with the spinal nerves ; and internal, to communicate with the sym- 

 pathetic filaments of the opposite side, and to be distributed to the 

 viscera. 



'W 



<yS CRANIAL GANGLIA. 



_ i f , . Ganglion of Ribes, 



/ / , Ciliary, or lenticular ganglion, 



g. ^^ Naso-palatine, or Cloquet's ganglion, 



Spheno-palatine, or Meckel's ganglion, 

 n Submaxillary ganglion, 



Otic, or Arnold's ganglion. 



6 



1. THE GANGLION OF RIBES is a small ganglion situated upon the 

 anterior communicating artery, and formed by the union of the 



54 



