CHAPTER XXII. 

 THE SYMPATHETIC NERVE SYSTEM. 



The sympathetic nerve system consists of a number of ganglia 

 united one to another by intervening cords of nerve-fibers. These 

 ganglia may for convenience of description be divided into three 

 groups : viz., the vertebral or lateral, the pre- vertebral or collateral, 

 and the peripheral or terminal. 



The vertebral ganglia are arranged in the form of chains, one on 

 each side of the vertebral column. The number of ganglia in the 

 chain varies in animals of different and in animals of the same 

 species. In man the number varies from 20 to 22. Each chain may 

 be divided into a cervical, a thoracic, a lumbar, a sacral, and a 

 coccygeal portion. The cervical portion is usually described as con- 

 sisting of three ganglia a superior, a middle, and an inferior. This 

 statement is open to question, however, as the middle one is fre- 

 quently absent and the inferior one is regarded by some anatomists 

 as belonging to the pre-vertebral series. The thoracic portion con- 

 sists of ten or eleven ganglia, the lumbar and sacral portions of four 

 each and the coccygeal portion of one, the so-called ganglion impar. 



The pre-vertebral ganglia are also united in the form of a chain 

 situated in the abdominal cavity. The ganglia constituting this 

 chain are known as the semilunar, the renal, the superior and inferior 

 mesenteric, and hypogastric. 



The peripheral ganglia are in more or less close relation with the 

 tissues and organs in different parts of the body. As members of 

 this group may be mentioned the ciliary or ophthalmic, the spheno- 

 palatine, the otic, the submaxillary and the sublingual ganglia; the 

 ganglia in walls of the heart, the respiratory organs, the intestines, 

 bladder, etc. 



The general arrangement of the sympathetic ganglia, their inter- 

 connecting cords and branches, is shown in Figs. 258 and 259. 



Structure of the Ganglia. Each ganglion consists of a capsule 

 or stroma of connective tissue in which are contained large numbers 

 of nerve-cells, nerve-fibers medullated and non-medullated, and 

 blood-vessels. The nerve-cells give origin to two or more dendrites, 

 which, perforating a nucleated capsule by which each cell is sur- 

 rounded, branch and rebranch and interlace to form a pericapsular 

 plexus. Each cell gives origin also to an axon, which as it leaves 

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