296 ENDOCRINE GLANDS 



PHYSIOLOGY OF THE THORACIC-LUMBAR, OR TRUE 

 SYMPATHETIC PART OF THE SYSTEM. 



The functions of this part are more general than that 

 of the rest of the vegetative system. The sympathetic 

 controls: 1. The smooth muscles of the blood vessels; 

 2. The smooth muscles of the skin; 3. The secretion 

 of the sudorific glands; 4. The smooth muscles sphinc- 

 ters of the gastro-intestinal tract from the stomach to the 

 rectum; 5. The muscles of the ureter, vesical trigone 

 and sphincter of the urethra; 6. The smooth muscles 

 of the genital organs in the two sexes, and the retractor 

 penis; 7. In the occular region the irido-dilator and the 

 muscle of Mueller. 



Furthermore, we must add to the functions of the true 

 sympathetic: acceleration of the heart, shortening of the 

 cardiac systole. From the point of view of general metab- 

 olism there are many changes, the most simple being 

 glycosuria and one of the most complicated the regulation 

 of body heat; finally, we must not forget the inhibitory 

 phenomena of the contraction of muscle, which counter- 

 balances the excito-motor innervation of the cranio pelvic 

 system of the vagus and pelvic plexus. 



This enumeration of the various functions of the 

 sympathetic would be of very little use if we did not go 

 more fully into details. 



As regards the vaso-motor system, there is nothing very 

 particular to say ; but as regards the gastro intestinal tract, 

 leaving aside temporarily the inhibition to contraction, 

 there are certain interesting facts in so far as the innerva- 

 tion of the smooth muscle sphincters are concerned. 



We know that the true sympathetic gives to a certain 

 part of the gastro-intestinal tract an innervation antago- 

 nistic to that of the vagus, but it is perfectly evident that 





