THE SYMPATHETIC NERVE. 483 



cases, several of the terminating filaments run into the anterior 

 coronary plexus.* 



The Posterior Branches are more numerous ; but run only a 

 short course, when they are merged in the anterior pulmonary 

 plexus formed by the par vagum. 



The Inferior Branches are the largest and the most abundant. 

 Some of them follow the pulmonary artery until its entrance 

 into the lungs, others are distributed upon the pulmonary veins; 

 but the greater number of them are arranged into two plexuses 

 called Coronary, from their observing the course of the corona- 

 ry arteries. The posterior coronary plexus is larger than the 

 other. It reaches the base of the heart, along the pulmonary 

 artery, and has its filaments distributed principally to the left 

 auricle and left ventricle, observing the course of the left corona- 

 ry artery and of its branches. The anterior coronary plexus gets 

 in front of the heart, between the aorta and the pulmonary ar- 

 tery. It anastomoses freely at its superior part with the other, 

 and is then distributed to the right auricle and ventricle, along 

 Che course of the right coronary artery and of its branches. 



Of the Thoracic Ganglions of the Sympathetic* 



These ganglions are twelve in number, and are placed on or 

 near the heads of the ribs, at the commencement of each in- 

 tercostal space, and are only covered by the pleura. Their 

 shape is irregular, and they differ also in size, being always 

 smaller than the cervical ganglions. The chord of the sympa- 

 thetic is continued, successively, from one ganglion to another, 

 so that they form a complete chain by their connexion with each 

 other. 



From each ganglion there proceeds one or more external 

 branches, which go outwards to anastomose with the intercostal 

 nerve of the corresponding part. Each ganglion also detaches 

 one or more internal branches or filaments to the adjacent parts 



* Scarpa. 



