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SYMPATHETIC NERVE. 



formed by the branches of the sympathetic 

 which pass down in front of the arteria in- 

 nominata on the right side, and the arch of 

 the aorta on the left side, corresponds to what 

 is termed by some the superficial cardiac 

 plexus, while the portion formed by the 

 branches of the sympathetic and vagus which 

 descend behind the arch of the aorta between 

 it and the trachea, is termed the deep cardiac 

 plexus. The branches which proceed from 

 the cardiac plexus are the following: () 

 Numerous filaments pass off from the upper 

 part of the plexus and surround the arch of 

 the aorta, as well as the large arterial trunks 

 which spring from the same. (6) Others pass 

 along the right and left pulmonary arteries, 

 and terminate in the pulmonary plexus, (e) 

 Offsets are also sent along the coronary ar- 

 teries, forming the anterior and posterior 

 coronary plexuses. The anterior coronary 

 plexus is chiefly derived from the superficial 

 portion of the cardiac pk-xus, and accom- 

 panies the anterior or right coronary artery 

 and its divisions ; the posterior coronary 

 plexus, chiefly derived from the left side of 

 the deeper portion of the cardiac plexus, is 

 situated at first behind the aorta and pulmo- 

 nary artery ; it then passes in front of the left 

 division of the pulmonary artery to the base 

 of the heart, and reaches the posterior co- 

 ronary artery, around which it forms an inter- 

 lacement of filaments. Numerous filaments 

 are distributed by it to the left side of the 

 heart, especially to the left ventricle : the 

 filaments of the anterior coronary plexus are 

 chiefly distributed to the right ventricle. The 

 nerve filaments which leave the coronary 

 plexuses do not all accompany the branches 

 of the coronary arteries, as was formerly sup- 

 posed; by far the greater number of them run 

 separately from the vessels, and are distributed 

 to the muscular substance of the heart. As 

 regards the arrangement of the nerves on 

 leaving the coronary plexuses, they appear to 

 be much more numerous on the ventricles 

 than the auricles. The filaments distribut- 

 ed to the former are very numerous ; they 

 are directed from the base to the apex of the 

 ventricle; those on the anterior surface passing 

 obliquely downwards from left to right, those 

 on the posterior surface from right to left ; 

 they thus in general cross obliquely the direc- 

 tion of the muscular fibres of the ventricles, 

 and often also that of the blood vessels. 

 Where they cross the latter, especially in the 

 heart of the young ox, they appear to bifur- 

 cate, so as to enclose the vessel in a loop ; 

 and at this point there is frequently, as is re- 

 presented by Dr. Lee, a small enlargement 

 which occasionally contains ganglionic matter.* 

 In their course along the surface of the ven- 

 tricles, neighbouring filaments frequently unite, 

 there being here also small ganglionic enlarge- 

 ments. According to Dr. Lee there are dis- 

 tinctly visible on the anterior surface of the 



* Dr. Lee, on the Ganglia and Nerves of the 

 Heart. Phil. Trans. 1849. 



young heifer's heart about ninety of these 

 ganglia or ganglionic enlargements. The left 

 ventricle appears to be more abundantly sup- 

 plied with nerves than that of the right side : 

 on the former they can be traced, extending 

 from base to apex, on the surface of the 

 latter they generally extend but a little way 

 down, when they sink into the muscular 

 substance. 



2. Plexus of the Thoracic Aorta. This con- 

 sists of delicate filaments which are derived 

 from the thoracic portion of the gangliated 

 chain of the sympathetic; several filaments also 

 pass between it and the cesophageal plexus. 

 Above, it is continued into the cardiac plexus, 

 from which it derives some branches, and below 

 it accompanies the vessel through the aortic 

 opening in the diaphragm, to terminate in 

 the coeliac plexus. 



C. Abdominal Plexuses of the Sympathetic 

 The abdominal plexuses of the sympathetic 

 are larger and more numerous than those oc- 

 curring in any of the other cavities of the 

 body. They correspond in number with the 

 branches of the abdominal aorta, and accom- 

 pany them in their course to the different 

 viscera. From the plexuses occurring on the 

 larger arteries, off-sets pass, which form a 

 number of subsidiary plexuses upon the smaller 

 vessels. The chief abdominal plexuses are the 

 coeliac, superior mescnteric, renal, inferior mesen- 

 teric, and superior and inferior hypogastric 

 plexuses. 



1 . The cceliac, solar, or epigastric plexus 

 is the largest of the plexuses of the sympa- 

 thetic. It is situated in the upper part of the 

 cavity of the abdomen, on both sides of the 

 aortic opening in the diaphragm, extending 

 across the anterior part of the aorta, and 

 is covered in front by the stomach. It sur- 

 rounds the cceliac axis, and extends down- 

 wards as far as the origin of the superior 

 mesenteric artery. It usually contains two 

 ganglia; these present a somewhat crescentic 

 form, and have on this account been termed 

 the semilunar ganglia. They are situated one 

 on each side of the plexus towards its upper 

 part, and are commonly surrounded by a num- 

 ber of smaller ganglia. The solar plexus 

 receives the splanchnic nerves, also some 

 branches from the posterior gastric plexus of 

 the pneumogastric ; it likewise receives fila- 

 ments from the plexus which has been de- 

 scribed as surrounding the thoracic aorta, as 

 well as others from the three or four upper 

 lumbar ganglia. The offsets from the plexus 

 present the same plexiform arrangement as 

 the plexus itself, and are named according to 

 the arteries which they accompany ; they are 

 the phrenic, or diaphragmatic, superior coro- 

 nary, hepatic, splenic, and renal plexuses. 



(a) The diaphragmatic plexuses are two 

 in number, a right and left, and consist of 

 several delicate filaments derived from the 

 upper part of the semilunar ganglia. They 

 often present several small ganglionic en- 

 largements, and accompany the diaphragmatic 

 arteries, sinking with them into the muscular 



