THE AUTONOMIC NERVOUS SYSTEM 



881 



stellatum for the fore limb, and the lower lumbar and upper sacral 

 ganglia for the hind limb. When they are stimulated, the muscular 

 fibers surrounding the sweat glands contract and squeeze out the sweat. 



SITUATION OF BLOOD 

 VESSELS 



Head and neck. 



Heart. 



Anterior extremity. 



Posterior extremity. 



Kidney. 



Spleen. 



Abdominal viscera. 



Pelvic viscera. 



SITUATION OF MOTOR 

 GANGLION CELLS 



Superior cervical ganglion. 



Ganglion stellatum and in- 

 ferior cervical ganglion. 



Ganglion stellatum. 



6th lumbar, 7th lumbar, and 

 1st sacral ganglion. 



Kenal ganglion. 

 Semilunar ganglion. 



Superior mesenteric ganglion 

 and semilunar ganglion. 



Inferior mesenteric ganglion. 



ROOTS CONTAINING CONNECTOR 

 NERVES 



1, 2, 3, 4, 5, thoracic; 2, 3, 4, give 

 maximum effect. 



I, 2, 3, 4, 5, thoracic; 2, 3, give 

 maximum. 



4, 5, 6, 7, 8, 9, thoracic, and 10 

 slightly. 



II, 12, 13. thoracic; 1, 2, lumbar 

 and' 3 slightly. 



4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 

 thoracic; 1, 2, 3, 4, lumbar. 



3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 

 thoracic; 1, 2, 3, lumbar. 



6, 7, 8, 9, 10, 11, 13, thoracic; 1, 2, 

 3, lumbar. 



1, 2, 3, 4, lumbar. 



(Gaskell) 



The ganglia for the pilomotor fibers are more widespread (extending 

 from the fourth thoracic to the coccygeal ganglia) ; but the connector 

 fibers are again strictly confined to the thoracicolumbar region. Stimu- 

 lation of these fibers causes movement of the hairs, or on hairless animals, 

 the condition called " goose skin." 



The Motor Nerves of the Muscles Surrounding the Segmental Duct. 

 It will be observed that the connector fibers to the abdominal and pel- 

 vic viscera are collected into two special nerve trunks, the greater and 

 the lesser (or lumbar) splanchnics. The collateral ganglia (semilunar 

 and superior and inferior mesenteries) with w r hich these connect, have 

 nothing to do with the segmental nerves, but their nerve cells send fibers 

 (postganglionic) which supply the various viscera not only with vaso- 

 motor fibers but also with the "sympathetic" fibers, which we have seen 

 exercise such an important control over their glandular and muscular 

 functions. 



All of the fibers contained in the lumbar splanchnics do not, however, 

 have their cell stations in the inferior mesenteric ganglia, but run 

 through it and proceed in the hypogastric nerves to find their effector 

 cells on the musculature of the various structures that are developed 

 from the Miillerian and Wolffian ducts i. e., of the ureters, uterus, Fal- 



