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VETERINARY PHYSIOLOGY 



mentors and accelerators of the heart's action. ^Vhen they 

 are cut the heart beats slower, therefore they are constantly 

 in action. When the peripheral end is stimulated, the rate 

 and force of the heart are increased. 



1. Course of the Fibres. — These are small medullated 

 fibres, which leave the spinal cord by the anterior roots of 



Fig. 182. — Simultaneous Tracing from Auricles and Ventricles. A., during 

 stimulation of the vagus ; B., during stimulation of the sympathetic. 

 Each downstroke marks a systole, each upstroke a diastole. (From 

 Roy and Adami. ) 



the 2nd, 3rd, and 4th dorsal nerves, and in most animals pass 

 to the stellate ganglion where they have their cell stations 

 (fig. 181). From the cells in this ganglion, non-medullated 

 fibres run on in the annulus of Vieussens, and from this and 

 from the inferior cervical ganglion, they pass out apparently 

 directly to the muscular fibres of the heart. 



