306 
SURGERY AND TRANSPLANTATION 
RECURRENT 
CARDIAC 
RT. STELLATE 
GANGLION 
CRRNIOYAGAL 
RT. LATERAL 
Figure 8. — Regional Denervation of the Canine Heart. 
Rt. Lateral View of Heart 
parasympathetic innervation of sinus node 
thetic innervation to the AV node. Our data con- 
firm these findings as well as delineate a second 
site of entry of sympathetic and parasympa- 
thetic innervation of the AV node. Sympathetic 
fibers of right-sided origin (Figure 9) reach 
the AV node from the junction of the inferior 
vena cava with the left atrium through the 
caudovagal nerve and occasionally the right 
thoracic vagus nerves. Right-sided sympathetic 
fibers reach the AV node along the great vessels 
through the recurrent cardiac and craniovagal 
nerves. Sympathetic fibers of left-sided origin 
reach the AV node through three sites of entry 
(Figure 10). The VLCN sends fibers along the 
left atrium to the AV node. The innominate 
nerve passes posterior to the heart and reaches 
the AV node by entering at the junction of the 
inferior vena cava with the left atrium. Both 
the VLCN and VMCN send fibers along the 
great vessels to reach the AV node. 
The parasympathetic fibers of right and left- 
sided origin enter the heart in two areas: at 
the junction of the inferior vena cava with the 
left atrium, and along the superior margin of 
the left atrium presumably from the pre- 
tracheal plexus (Figures 11 and 12). Of left- 
sided origin, the left thoracic vagus sends 
parasympathetic fibers to the AV node both 
along the junction of the inferior vena cava 
with the left atrium and at the superior margin 
of the left atrium (Figure 11). Parasympa- 
thetic fibers of right-sided origin reach the AV 
node through the craniovagal and caudovagal 
nerves as well as through the right thoracic 
vagus nerve by entering at the superior margin 
of the left atrium, while fibers from the recur- 
