THE SYMPATHETIC NERVES. 



35? 



THE SYMPATHETIC NERVES. 



The nerves of the sympathetic system are distributed to the internal viscera, 

 together with other glandular organs of the body, to the heart and blood-vessels. 



Fig. 228. DIAGRAMMATIC OUTLINE OF THE SYMPATHETIC CORD OF 



ONE SIDE IN CONNECTION WITH THE SPINAL NERVES. (Allen 



Thomson. ) 



The full description of this figure will be found at p. 275. 



On the right side the following letters indicate parts of the 

 sympathetic nerves, viz., a, superior cerviccil ganglion, com- 

 municating with the upper cervical spinal nerves, and continued 

 below into the great sympathetic cord ; b, middle cervical gang- 

 lion ; c, d, lower cervical ganglion united with the first dorsal ; 

 d f , eleventh dorsal ganglion ; from the sixth to the ninth dorsal 

 ganglia the origins of the great splanchnic nerve are shown, and from 

 the tenth that of the small splanchnic nerve ; /, first lumbar 

 ganglion; ss, first sacral ganglion. In the whole extent of the sym- 

 pathetic cord the twigs of union with the spinal nerves are shown. 



and to the unstriped muscles of the body generally. 

 Some organs, however, receive nerves also from the 

 cerebro-spinal system directly, as the lungs, the heart, 

 and the upper and lower parts of the alimentary 

 canal ; and those viscera which are not supplied 

 directly in this way receive fibres derived originally 

 from cerebro-spinal nerves through their sympathetic 

 plexuses. 



This division of the nervous system consists of a 

 somewhat complicated collection of ganglia, cords and 

 plexuses, the parts of which may, for convenience, be 

 classified in two groups, viz., the principal gangliated 

 cords, and the great prevertebral plexuses, with the 

 nerves proceeding from them. The ganglia of union with 

 cranial nerves, viz., the ciliary, spheno-palatine, otic, and 

 submaxillary ganglia, which agree in their connections 

 and structure with the ganglia of the sympathetic 

 system, have already been described in connection 

 with the fifth nerve. 



The foundation of the sympathetic is constituted 

 by medullated fibres, for the most part of very small 

 size (2'fyi and less), which pass by means of the white 

 rami communicantes from certain of the cerebro-spinal 

 nerves, into the cords and ganglia of the sympathetic. 

 Here some of the fibres terminate in arborisations 

 around the cells of the ganglia of the great sympa- 

 thetic cord (vertebral or lateral ganglia of Gaskell), 

 while others, which frequently run for a variable 

 distance either upwards or downwards in the cord, 

 pass by the rami efferentes to the prevertebral plexuses, 

 where they may end similarly in the ganglia of those 

 plexuses (prevertebral or collateral gang lia, Gaskell), or 

 they may be continued on to the secondary plexuses, to 

 break up in the ganglia close to or in the organs 

 supplied (terminal ganglia, Gaskell). Some of the 

 medullated fibres also pass through the several 

 plexuses to the viscera or other parts without being 



