SYMPATHETIC CARDIAC SERVES 



155 



pare this reading with the former one. What conclusions 

 can yon draw? 



3. If the animal is in fair condition, isolate the right 

 subclavian vein at the apex of the chest (see Figs. 133 and 

 184). Tie tightly two ligatures around the vein and sec- 

 tion the vessel between the ligatures. Pick up the ansa 

 subclavia (annulus Vieussenii) and stimulate some of the 



Depressor nerve 

 (running with 

 the vagus trunk 

 on the right) 



Union between 

 middle cervical 

 ganglion and 

 vagus nerve 



Fibers from 

 spinal cord 

 to stellate 

 ganglion 



Right 

 stellate 

 (inf. cervical) 

 ganglion 



Communicating 

 branches between 

 the vagus and the 

 stellate ganglion 



-Vagus trunks-ff 

 Ceik * - IK 



. 

 athetic cords 



Depressor nerves 

 Separate on 

 the left) 



Middle cervical 

 ganglia 



Recur rent-i 



laryngeal 



nerves 



Ansa 

 subclavia 



Cardiac 

 fibers 



Union between 

 middle cervical 

 ganglion and 

 vagus nerve 



Left stellate 

 inf. cervical) 

 ^ganglion 



Fibers from 

 spinal cord to 

 stellate gang. 



t> 

 Depressor nerve 



Cardiac nerves 



from the 

 stellate ganglion 



Fig. 148. The innervaticm of the heart in the cat. (After Boehm. ) 



small fibers passing from the ganglia or the anterior loop 

 of the annulus toward the heart. These will probably be 

 derived from the vagus and the heart will then be slowed. 

 Pick up some others of the small fibers lower down and 

 stimulate them. You will probably find a fiber which does 

 not cause any slowing of the heart and no immediate effect 

 may follow its stimulation. But if you get a pure sympa- 

 thetic cardiac fiber, stimulation of this nerve will, after a 



