688 



PHYSIOLOGY OF SPECIAL NERVES 



to the third to the eighth cervical nerves and the first to the third (fourth) 

 thoracic nerves: they make their exit through the fifth to the eighth thoracic 

 roots. Vasomotor and sweat nerves for the fore paw are contained in the fourth 

 to the ninth thoracic roots. They unite with cells in the stellate ganglion, from 

 which postganglionic fibers are given off to the brachial nerves, the latter like 

 the pilomotor fibers running in the posterior branches of those nerves. This 

 ganglion also sends accelerator nerves to the heart and possibly vasomotor nerves 

 to the lungs; but it is not yet conclusively proved that these nerves actually 

 proceed from cells in the stellate ganglion. 



Those spinal nerve roots which send out fibers to the chain ganglia lying 

 distally to the stellate ganglion, each supply three, four or more ganglia. The 

 postganglionic fibers (pilomotor and vasomotor) unite with the corresponding 

 spinal nerves and accompany their dorso-cutaneous branches to the skin. 



The vasomotor and sweat nerves to the hind paw pass out probably in the 

 twelfth thoracic to the second lumbar nerve roots; they unite with the sixth 

 lumbar to the second sacral ganglia to be continued in the cutaneous branches 

 of the spinal nerves. 



The inhibitory and vasomotor nerves contained in the splanchnic are con- 

 nected for the most part with cells in the solar plexus and have no relay station 

 in the chain ganglia. They proceed from all roots between the fifth thoracic 

 and second lumbar nerves. 



The organs of the pelvis receive nerves both from the lumbar sympathetic 

 and the sacral (cf. page 393). The former arise from all roots between the 

 twelfth thoracic and fifth lumbar, and traverse the sympathetic cord either 

 to the inferior mesenteric ganglion or to the sacral ganglia. Those entering 

 the inferior mesenteric ganglion unite for the most part with its cells, but to 

 a less extent also with ganglion cells situated in the peripheral organs. Most 

 of the sympathetic nerves to the external genital organs are connected with 

 cells in the sacral ganglia. 



The autonomic fibers passing out through the first to the third sacral roots 

 and uniting to form the nervi erigentes connect with the cells of ganglia strewn 

 along their course and lying for the most part in the immediate vicinity of 

 the organs for which they are destined. 



GANGLIA OF THE SYMPATHETIC SYSTEM 



On the basis of his experiments upon animals and on the basis of 

 comparative anatomy, Langley has constructed the above table illustrating 



