750 THE NERVOUS SYSTEM. 



the nerve, through which the fibres of the spinal accessory pass unchanged, being 

 principally distributed to the pharyngeal and superior laryngeal branches of the 

 vagus ; but some of the filaments from it are continued into the trunk of the vagus 

 below the ganglion, to be distributed with the recurrent laryngeal nerve, and prob- 

 ably also with the cardiac nerves. The nerve passes vertically down the neck 

 within the sheath of the carotid vessels lying between the internal carotid artery 

 and internal jugular vein as far as the thyroid cartilage, and then between the same 

 vein and the common carotid to the root of the neck. Here the course of the nerve 

 becomes different on the two sides of the body. 



On the right side the nerve passes across the subclavian artery between it and 

 the right innominate vein, and descends by the side of the trachea to the back part 

 of the root of the lung, where it spreads out in a plexiform network (posterior pul- 

 monary), from the lower part of which two cords descend upon the oesophagus, on 

 which they divide, forming, with branches from the opposite nerve, the oesophageal 

 plexus (plexus gulce); below, these branches are collected into a single cord, which 

 runs along the back part of the O3sophagus, enters the abdomen, and is distributed 

 to the posterior surface of the stomach, joining the left side of the solar plexus, and 

 sending filaments to the splenic plexus and a considerable branch to the coeliac 

 plexus. 



On the left side the pneumogastric nerve enters the chest between the left 

 carotid and subclavian arteries, behind the left innominate vein. It crosses the 

 arch of the aorta and descends behind the root of the left lung, forming the poste- 

 rior pulmonary plexus, and along the anterior surface of the oesophagus, where it 

 unites with the nerve of the right side in forming the plexus guise, to the stomach, 

 distributing branches over its anterior surface, some extending over the great 

 cul-de-sac, and others along the lesser curvature. Filaments from these branches 

 enter the gastro-hepatic omentum and join the hepatic plexus. 



The ganglion of the root is of a grayish color, circular in form, about 

 two lines in diameter, and resembles the ganglion on the large root of the fifth 

 nerve. 



Connecting Branches. To this ganglion the accessory portion of the spinal 

 accessory nerve is connected by several dedicate filaments ; it also has a communi- 

 cating twig with the petrous ganglion of the glosso-pharyngeal, with the facial 

 nerve by means of its (the ganglion's) auricular branch, and with sympathetic 

 by means of an ascending filament from the superior cervical ganglion. 



The ganglion of the trunk (inferior) is a plexiform cord, cylindrical in 

 form, of a reddish color, and about an inch in length ; it involves the Avhole 

 of the fibres of the nerve, and passing through it is the accessory portion of 

 the spinal accessory nerve, which blends with the pneumogastric below the 

 ganglion, and is then principally continued into its pharyngeal and superior 

 laryngeal branches. 



Connecting Branches. This ganglion is connected with the hypoglossal, the 

 superior cervical ganglion of the sympathetic, and the loop between the first and 

 second cervical nerves. 



The branches of the pneumogastric are 



T ^ . , f ( Meningeal. 



In the jugular fossa . . . ^ Auricu i ar . 



Pharyngeal. 



In the neck 



In the thorax 



Posterior pulmonary. 

 (Esophageal. 

 In the abdomen . . Gastric. 



Superior laryngeal. 

 Recurrent laryngeal. 

 Cervical cardiac. 

 Thoracic cardiac. 

 Anterior pulmonary. 



