1 6 THE INVOL UNTAR Y NER VO US S YSTEM 



All these collateral ganglionic masses are connected with the 

 central nervous system by means of the splanchnic nerves. It 

 was once thought that, just as the rami communicantes connected 

 the central nervous system with the ganglia of the lateral chain, 

 so the splanchnics connected the ganglia of the lateral chain with 

 the collateral ganglionic masses. Milne Edwards gave the name 

 rami efferentes to the whole set of nerves, which were held to 

 connect these two groups. There is, however, in reality no such 

 connexion, the splanchnic nerves are simply rami communicantes 

 direct from the central nervous system to the cells of the col- 

 lateral chain, the fibres of which lie along the lateral or main 

 chain for part of their course and so appear to spring from the 

 ganglia of that chain. 



The splanchnic nerves are divided into two very distinct 

 groups, an upper or superior group, which contains the largest 

 ner ve the splanchnic nerve proper and connects with the 

 superior mesenteric, semilunar, and renal ganglia, and a lower 

 or inferior group, consisting of three to four nerves which 

 connect with the inferior mesenteric ganglion. The whole set 

 may be called the abdominal splanchnic nerves, and in consider- 

 ation of their relation to the roots of the spinal cord it is often 

 convenient to speak of the superior group as the thoracic 

 splanchnics and of the inferior group as the lumbar splanchnics. 



The lateral ganglia (Fig. 4) form a segmentally arranged 

 chain corresponding to the segmental spinal nerves, each 

 ganglion sending sympathetic fibres to its corresponding nerve 

 and to its corresponding spinal segment. The upper ganglia 

 in the thoracic region have become fused to form the large 

 ganglion stellatum ; and the ganglia of the cervical region have 

 fused to form the inferior and superior cervical ganglia, the 

 latter of which supplies the three foremost cervical nerves, the 

 rest being supplied by sympathetic fibres from the inferior cervical 

 ganglion and from the ramus vertebralis, a striking grey ramus 

 from the ganglion stellatum, which supplies the four lower cervical 

 nerves and corresponding spinal segments. 



The evidence up to this point is clear, that the so-called sym- 

 pathetic system consists of an out-flow from the spinal cord of 

 fine medullated efferent nerves, which terminate in or around 

 nerve cells, whose fibres (sympathetic or post-ganglionic) proceed 

 to and supply the peripheral organs. Although I was strongly 



