440 THORACIC GANGLIA. 



Jaryngeal, At the root of the neck it divides into several branches, -\\hick 

 pass some before and some behind the subclavian artery; it communicates 

 \vith the superior and inferior cardiac, and with the pneumogastric and 

 recurrent nerves, and descends to the bifurcation of the trachea, to the 

 great cardiac plexus. 



The Inferior cardiac nerve (nervus cardiacus minor) arises from the in- 

 ferior cervical ganglion, communicates freely with the recurrent 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, situ- 

 ated 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 pneumogastric, and gives off nu- 

 merous 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 and descendens noni nerve, and first 

 thoracic ganglion. 



The Anterior cardiac plexus is situated in front of the ascending aorta, 

 near its origin. It is formed by the communications of filaments that pro- 

 ceed from three different sources, namely, from the superior cardiac nerves, 

 crossing the arch of the aorta ; from the cardiac ganglion beneath the 

 arch ; and from the great cardiac plexus, passing between the ascending 

 aorta and the right auricle. The anterior cardiac plexus supplies the an- 

 terior 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 ascend- 

 ing aorta, near 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 posterior 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 grey 

 colour and pearly lustre of the other sympathetic ganglia ; they rest upon 

 the heads of the ribs, and are covered in by the pleura costalis. The two 

 first ganglia and the last are usually the largest. 



Their branches are superior, inferior, external, and internal. 



The superior and inferior are prolongations of the substance of the gan- 

 glia rather than branches ; the former to communicate with the ganglion 

 above, the latter with that below. 



vical ganglion. 11. The inferior cervical ganglion. 12. The roots of the great splanch- 

 nic mvrve, arising: from the dorsal ganglia. 13. The lesser splanchnic nerve. 14. The 

 lenal plexus. 15. The solar plexus. 16. The mesenteric plexus. 17. The lumbar 

 ganglia. 18. Tho sacral ganglia. 19. The vesical plexus. 20. The rectal plexus. 21. 

 Tbe ivimba; plexus, (cerebro-spinal.) 



