BRANCHES OF PNEUMO-GASTRIC NERVE. 623 



CARDIAC BRANCHES. 



Branches to the heart are given off by the pneumo-gastric nerve both in 

 the neck and in the thorax. 



The cervical cardiac branches arise at both the upper and the lower part 

 of the neck. The upper branches are small, and join the cardiac nerves of 

 the sympathetic. The loiver, a single branch, arises as the pneumo-gastric 

 nerve is about to enter the chest. On the right side this branch lies by the 

 side of the innominate artery, and joins one of the cardiac nerves destined 

 for the deep cardiac plexus ; it gives some filaments to the coats of the 

 aorta. The branch of the left side crosses the arch of the aorta, and ends 

 in the superficial cardiac plexus. 



The thoracic cardiac branches of the right side leave the trunk of the 

 pneumo-gastric as this nerve lies by the side of the trachea, and some 

 are also derived from the first part of the recurrent branch : they pass 

 inwards on the air- tube, and end in the deep cardiac plexus. The 

 corresponding branches of the left side come from the left recurrent 

 laryngeal nerve. 



PULMONARY BRANCHES. 



Two sets of pulmonary branches are distributed from the pneumo-gastric 

 nerve to the lung ; and they reach the root of the lung, one on its fore part, 

 the other on its posterior aspect. The anterior pulmonary nerves, two or 

 three in number, are of small size. They join with filaments of the 

 sympathetic ramified on the pulmonary artery, and with these nerves 

 constitute the anterior pulmonary plexus. Behind the root of the lung the 

 pneumo-gastric nerve becomes flattened, and gives several branches of much 

 larger size than the anterior branches, which, with filaments derived from 

 the second, third, and fourth thoracic ganglia of the sympathetic, form the 

 posterior pulmonary plexus. Offsets from this plexus extend along the rami- 

 fications of the air-tube through the substance of the lung. 



CESOPHAGEAL BRANCHES. 



The oesophagus within the thorax receives branches from the pneumo- 

 gastric nerves, both above and below the pulmonary branches. The lower 

 branches are the larger, and are derived from the cesophageal plexus, formed 

 by connecting cords between the nerves of the right and left sides, while 

 they lie in contact with the oesophagus. 



GASTRIC BRANCHES. 



The branches distributed to the stomach (gastric nerves) are the terminal 

 branches of bath pneumo-gastric nerves. The nerve of the left side, on 

 arriving in front of the oesophagus, opposite the cardiac orifice of the 

 stomach, divides into many branches : the largest of these extend over the fore 

 part of the stomach ; others lie along its small curvature, and unite with 

 branches of the right nerve and the sympathetic ; and some filaments are 

 continued between the layers of the small omentum to the hepatic plexus. 

 The right pneumo-gastric nerve descends to the stomach on the back of the 

 gullet and distributes branches to the posterior surface of the organ : a part 

 of this nerve is continued from the stomach to the left side of the coeliac 

 plexus, and to the splenic plexus of the sympathetic. 



Summary. The pneumo-gastric nerves supply branches to the upper part 

 of the alimentary canal, viz., the pharynx, oesophagus, and stomach with 

 the liver and spleen ; and t6 the respiratory passages, namely, the larynx, 



