W. p. GEIS AND M. P. KAYE 
307 
Figure 9. — Regional Denervation of the Canine Heart. 
Rt. Lateral View of Heart 
sympathetic innervation of AV node, rt.-sided origin 
rent cardiac nerve, the caudovagal nerve and 
the right thoracic vagus nerve enter at the 
junction of the inferior vena cava with the left 
atrium (Figure 12). 
Sympathetic innervation of the sinus node 
enters the heart along tv^^o pathv^ays (Figure 
1 7). The recurrent cardiac nerve, right stellate 
cardiac nerve, VMCN, and VLCN all send sym- 
pathetic fibers along the intra-pericardial SVC 
to the sinus node. The VLCN and the VMCN 
also send fibers subjacent to the adventitia of 
the aorta and pulmonary artery to reach the 
sinus node. Parasympathetic fibers to the sinus 
node enter the heart along the superior margin 
j of the LA, the SVC, and the inter-atrial groove. 
The left vagus nerve, the craniovagal nerve, the 
caudovagal nerve and the recurrent cardiac 
nerve all send fibers along the SVC. Both the 
left and right thoracic vagus nerves send fibers 
along the inter-atrial groove, v^hile the cranio- 
vagal nerve also sends fibers to the sinus node 
via the superior margin of the LA (Figure 8). 
SUMMARY 
These data demonstrate the sites of entry of 
autonomic cardiac nerves to the heart. The 
physiological consequences of interruption of 
these neural pathways have been discussed. 
Awareness of the pathways of these neural 
elements must be considered when the technical 
aspects of cardiac manipulation and implanta- 
tion of recording devices are undertaken. 
