202 THE BLOOD VASCULAR SYSTEM 



Nerve Supply. The nerve supply of the vascular system is by means 

 of fine branches from the cerebrospinal and sympathetic systems. In the 

 heart these minute nerve trunks end in the various cardiac ganglia, 

 most of which are found in the connective tissue of the heart, e.g., the 

 coronal plexuses about the orifices of the aorta and pulmonary artery. 

 From these ganglia sensory nerve fibers are distributed to the endocar- 

 dium and epicardium, and motor fibers to the myocardium. The most of 

 the former are connected with the vagus, the latter with the sympathetic 

 trunks. Through both the vagus and the sympathetic trunks are dis- 

 tributed also efferent cerebrospinal fibers : the accessory nerve through 

 the vagus contributes 'inhibitory' fibers, the cervical spinal nerves through 

 the inferior cervical ganglia contribute 'acceleratory' fibers. 



From the cardiac ganglia branches pass to form a coarse plexus in 

 the connective tissue between the muscle bundles, the perimysial plexus, 

 from the branches of which a fine plexus is distributed to the endo- 

 mysium. The terminal branches end in relation with the surface of the 

 muscle fibers. 



The pericardium contains numerous encapsulated nerve endings 

 (corpuscles of Golgi and Mazzoni). According to Martynoff (Arch, 

 mikr. Anat., vol. 84, 191-i) unencapsulated endings also are present, of 

 three types : coils, dendriform terminal ramifications, and modified den- 

 driform endings. He describes also naked terminal filaments ending on 

 the bases of the mesothelial covering cells. 



The Hood-vessels are similarly supplied, minute ganglia occurring 

 here and there in the adventitia or adjacent connective tissue. From 

 these ganglia sensory branches are distributed to the adventitia and in- 

 tima and motor branches to the tunica media. Naked nerve fibrils can bo 

 traced to the smallest blood-vessels, and even in the capillaries terminal 

 fibrillse are found in relation with the endothelial wall. 



