342 THE CIRCULATION OF THE BLOOD. [CHAP. XXVlll. 



These nerves form by their frequent anastomosis a plexus called the 

 cardiac plexus. It is situated upon the aorta and pulmonary 

 artery, just as they have issued from their respective ventricles, 

 and is commonly described as consisting of two portions the 

 superficial cardiac plexus, which corresponds to the concavity of 

 the arch of the aorta, and lies in front of the right branch of the 

 pulmonary artery; the deep cardiac plexus, which is much the 

 larger portion, and lies behind the arch of the aorta between it 

 and the bifurcation of the trachea. To the formation of these 

 plexuses, branches derived from the vagus and the sympathetic on 

 both sides contribute. 



The greatest part of the nerves which emanate from these 

 plexuses entwine around and accompany the right and left coronary 

 arteries, forming the anterior and posterior coronary plexuses. 

 From these, nerves pass to the auricles and ventricles, but chiefly 

 to the latter. A ganglion, described first by Wrisberg, and called 

 after him ganglion cardiacum Wrisbergii, is generally found in 

 front of the left auricle, and behind the aorta. Scarpa has also 

 described gangliform enlargements of the nerves on the anterior 

 surface of the ventricles, to one of which, situated on the anterior 

 surface of the horse's heart, half-way down the anterior groove, 

 he refers under the name of "cardiaci sinistri ganglion insigne."* 

 It is probable, however, that none of these latter enlargements are 

 truly ganglionic in their nature. 



Remak describes numerous microscopic ganglia on the nerves of 

 the heart of the calf. We have seen some of these small ganglia 

 upon the surface of the auricles in the calf's heart, although we 

 have not succeeded in detecting them on the surface of the ven- 

 tricles, nor in the substance of the septum, as delineated by Remak. 

 We can vouch for the truly ganglionic nature of those which we 

 have seen from the unequivocal existence of vesicular matter in 

 them.f 



Some elaborate dissections of the nerves of the heart have lately 

 been made by Dr. Robert Lee, J from which it appears that the heart 

 is more largely supplied with nerves than had been hitherto sup- 

 posed, and that a larger number go directly to the muscular 

 structure of the heart, independently of the arteries, than had been 

 admitted by previous anatomists. Upon these nerves numerous 



* Scarpa, Tabulae Anatomicse. Ticin. 1 794. Tab. vii. fig. 1. 



t Remak, Neurologischen Erlauterungen. Muller's Archiv. 1844. Tafel xii. 



% Phil. Trans. 1849. 



