984 NEUROLOGY 



communicantes to the corresponding ganglia. The rami communicantes are o: 

 considerable length, and accompany the lumbar arteries around the sides of the 

 bodies of the vertebrae, passing beneath the fibrous arches from which some of the 

 fibers of the Psoas major arise. 



Of the branches of distribution, some pass in front of the aorta, and join the aortic 

 plexus; others descend in front of the common iliac arteries, and assist in forming 

 the hypogastric plexus. 



THE PELVIC PORTION OF THE SYMPATHETIC SYSTEM (PARS 

 PELVINA S. SYMPATHICI). 



The pelvic portion of each sympathetic trunk is situated in front of the sacrum, 

 medial to the anterior sacral foramina. It consists of four or five small sacral 

 ganglia, connected together by interganglionic cords, and continuous above with 

 the abdominal portion. Below, the two pelvic sympathetic trunks converge, and 

 end on the front of the coccyx in a small ganglion, the ganglion impar. 



Gray rami communicantes pass from the ganglia to the sacral and coccygeal 

 nerves. No white rami communicantes are given to this part of the gangliated 

 cord, but the visceral branches which arise from the third and fourth, and sometimes 

 from the second, sacral, and run directly to the pelvic plexuses, are regarded as 

 white rami communicantes. 



The branches of distribution communicate on the front of the sacrum w r ith the 

 corresponding branches from the opposite side; some, from the first two ganglia, 

 pass to join the pelvic plexus, and others form a plexus, which accompanies the 

 middle sacral artery and sends filaments to the glomus coccygeum (coccygeal body), 



THE GREAT PLEXUSES OF THE SYMPATHETIC SYSTEM. 



The great plexuses of the sympathetic are aggregations of nerves and ganglia, 

 situated in the thoracic, abdominal, and pelvic cavities, and named the cardiac, 

 celiac, and hypogastric plexuses. They consist not only of sympathetic fibers 

 derived from the ganglia, but of fibers from the medulla spinalis, which are con- 

 veyed through the white rami communicantes. From the plexuses branches are 

 given to the thoracic, abdominal, and pelvic viscera. 



The Cardiac Plexus (Plexus Cardiacus) (Fig. 838). 



The cardiac plexus is situated at the base of the heart, and is divided into a super- 

 ficial part, which lies in the concavity of the aortic arch, and a deep part, between 

 the aortic arch and the trachea. The two parts are, however, closely connected. 



The superficial part of the cardiac plexus lies beneath the arch of the aorta, 

 in front of the right pulmonary artery. It is formed by the superior cardiac branch 

 of the left sympathetic and the lower superior cervical cardiac branch of the left 

 vagus. A small ganglion, the cardiac ganglion of Wrisberg, is occasionally found 

 connected with these nerves at their point of junction. This ganglion, when 

 present, is situated immediately beneath the arch of the aorta, on the right side 

 of the ligamentum arteriosum. The superficial part of the cardiac plexus gives 

 branches (a) to the deep part of the plexus; (6) to the anterior coronary plexus; 

 and (c) to the left anterior pulmonary plexus. 



The deep part of the cardiac plexus is situated in front of the bifurcation of 

 the trachea, above the point of division of the pulmonary artery, and behind the 

 aortic arch. It is formed by the cardiac nerves derived from the cervical ganglia 

 of the sympathetic, and the cardiac branches of the vagus and recurrent nerves. 

 The only cardiac nerves which do not enter into the formation of the deep part 







