432 CARDIAC GANGLION THORACIC GANGLIA. 



of communication between the superior and inferior. It is the largest 

 of the three nerves, and lies nearly parallel with the recurrent laryn- 

 geal. At the root of the neck it divides into several branches, which 

 pass some before and some behind the subclavian artery ; it com- 

 municates with the superior and inferior cardiac, and with the 

 pneumogastric and recurrent nerves, and descends to the bifurca- 

 tion of the trachea, to the great cardiac plexus. 



The Inferior cardiac nerve (nervus cardiacus minor) arises from 

 the inferior cervical ganglion, communicates freely with the recur- 

 rent laryngeal and middle cardiac nerves, and descends to the front 

 of the bifurcation of the trachea, to join the great cardiac plexus. 



The Cardiac ganglion is a ganglionic enlargement of variable 

 size, situated beneath the arch of the aorta, to the right side of the 

 ligament of the ductus arteriosus. It receives the superior cardiac 

 nerves of opposite sides of the neck, and a branch from the pneu- 

 mogastric nerve, and gives off numerous branches to the cardiac 

 plexuses. 



The Great cardiac plexus is situated upon the bifurcation of the 

 trachea, above the right pulmonary artery, and behind the arch of 

 the aorta. It is formed by the convergence of the middle and 

 inferior cardiac nerves, and by branches from the pneumogastric 

 nerve. 



The Anterior cardiac plexus is situated in front of the ascending 

 aorta, near to its origin. It is formed by the communications of 

 filaments that proceed from three different sources. 1st, from the 

 superior cardiac nerves, crossing the arch of the aorta ; 2dly, from 

 the cardiac ganglion beneath the arch ; and, 3dly, from the great 

 cardiac plexus, passing between the ascending aorta and the right 

 auricle. The anterior cardiac plexus supplies the anterior aspect 

 of the heart, distributing numerous filaments with the left coronary 

 artery, which- form the anterior coronary plexus. 



The Posterior cardiac plexus is formed by numerous branches 

 from the great cardiac plexus, and is situated upon the posterior 

 part of the ascending aorta, near to its origin. It divides into two 

 sets of branches : one set accompanying the right coronary artery 

 in the auriculo-ventricular sulcus ; the other set joining the artery 

 on the posterior aspect of the heart. They both together constitute 

 the posterior coronary plexus. 



The great cardiac plexus likewise gives branches to the auricles 

 of the heart, and others, to assist in forming the anterior and poste- 

 rior pulmonary plexuses. 



THORACIC GANGLIA. 



The Thoracic ganglia are twelve in number on each side. They 

 are flattened and triangular, or irregular in form, and present the 

 peculiar gray colour and pearly lustre of the other sympathetic 

 ganglia ; they rest upon the heads of the ribs, and arc covered in 



