642 SYMPATHETIC AND OTHER SYSTEMS OF NERVES. 



curari. Whether these fibres arise from a cranial nerve, or reach the 

 fifth nerve from the sympathetic, has not been investigated. 



Sympathetic Fibkes supplying the Thoeacic and 

 Abdominal Visceea, 



Thoracic viscera. — The relations of the sympathetic nerves to the 

 heart and lungs have been already noticed in previous articles in this 

 volume, so that I need only mention a few points here. 



The accelerator fibres for the heart proceed from a rather more 

 anterior series of the spinal nerves than do the vasomotor fibres for the 

 lungs. The accelerator fibres are contained chiefly in the second, third, 

 and fourth thoracic nerves, some fibres also at times being present in 

 the first and fifth. 1 The vasomotor fibres for the lungs arise, according 

 to Bradford and Dean, from the third to the seventh thoracic nerves 

 inclusive. 2 



The fibres proceed partly by strands leaving the ganglion stellatum, 

 forming what is sometimes called the nervus accelerans, and partly by 

 strands leaving the inferior cervical ganglion. The nerve cell connection 

 of the pre-ganglionic fibres has not been worked out, but it is probable 

 that the majority end in connection with the cells of the ganglion stella- 

 tum, and the minority in connection with the cells of the inferior cervical 

 ganglion. Assuming that the accelerator fibres do end in the ganglion 

 stellatum, we have the curious fact that, whilst the origins of the nerve 

 fibres supplying the external carotid and the heart are practically the 

 same, the nerve cells with which the nerve fibres are connected have 

 become widely separated, and that the first, second, and usually also 

 the third thoracic nerves are connected with no cells of the ganglion 

 stellatum, except those supplying the thoracic viscera. 



Upper abdominal viscera.— The nerve fibres to the upper abdo- 

 minal viscera run by way of the splanchnic nerves, the solar ganglia 

 and the bundles of nerve fibres accompanying the coeliac, the superior 

 mesenteric, and the renal arteries. The splanchnic nerves on each side 

 consist of the main splanchnic, and of two or three smaller nerves. 

 When there are three nerves only, as is generally the case, they are 

 sometimes spoken of as the great, the small, and the smallest splanchnic. 

 Not infrequently the term " splanchnic nerve " is used to include all 

 three nerves. 



The solar ganglia, which, it will be remembered, are pre-vertebral 

 ganglia, consist of a group of ganglia joined by nerve strands. These 

 are in close connection with the coeliac, superior mesenteric, and renal 

 arteries. From the ganglia proceed nerve fibres, which accompany and 

 innervate the arteries, and innervate also the organs to which the 

 arteries run. The fibres which accompany the arterial trunks arise in 

 large part, though by no means wholly, from different ganglionic 

 masses, so that we may speak of the cceliac ganglia, the superior 

 mesenteric ganglia, and the renal ganglia, as sending their fibres in the 

 main to their respective arteries. Certain of the renal ganglia are close 

 to the hilum of the kidney, but it is convenient to include them in the 

 solar ganglia. 



The several abdominal organs, with the exception of the kidney, 



1 Of. Phil. Trans., London, 1892, vol. clxxxiii. p. 107. 



2 Proc. Roy. Soc. London, 1889, vol. xlv. p. 369. 



