1088 



PHYSIOLOGY 



ganglion, whence they run up through the second ganglion and 

 the annulus of Vieussens to the first ganglion ; they then pass 

 into the cervical sympathetic strand to the ganglion trunci vagi ; 

 here they join the vagus and pass down with the true vagus fibres 

 to the heart. 



In the dog (Fig. 448) the sympathetic fibres leave the spinal cord by 

 the anterior roots of the second and third dorsal nerves, run in the 

 white rami communicantes to the stellate ganglion, and thence by the 



>-Juq. Ganql. Vagus 



Vago-symparhe-Hc 



Subclav. art". 



N.1II. 



Splanchn. n. 

 Inl-esl-. arf 



FIG. 447. Sympathetic chain of frog (right side) to show connection with 

 vagus nerve. The sympathetic ganglia with their branches are black. 

 Of .the peripheral branches only the splanchnic nerve is represented. 

 (Modified from ECKER.) 



I 



annulus of Vieussens to the inferior cervical ganglion. Cardiac 

 branches convey the sympathetic fibres to the heart and are given off 

 from the stellate ganglion, the inferior cervical ganglion, and from the 

 trunk of the vagus. 



By the nicotine method it is possible to trace out the cell con- 

 nections of these fibres. As they leave the cord they are medullated 

 nerve fibres, similar to the other fibres making up the visceral outflow 

 throughout the dorsal region ; the white fibres pass along the ramus 

 comrnunicans to the stellate ganglion, where they end, forming 

 synapses with the cells of the ganglion. Here fresh relays of fibres, 



