1008 THE NERVE SYSTEM 



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

 ing filaments to the splenic plexus and a considerable branch to the coeliac plexus. 



On the left side the vagus nerve enters the thorax 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 posterior pul- 

 monary plexus (plexus pulmonalis posterior), and along the anterior surface of the 

 oesophagus, where it unites with the nerve of the right side in forming the cesopha- 

 geal plexus. It passes to the stomach, distributing branches over the anterior 

 surface of that viscus, some extending over the fundus, and others along the lesser 

 curvature. Filaments from these branches enter the gastrohepatic omentum and 

 join the hepatic plexus. 



The ganglion of the root or the jugular ganglion (ganglion jugulare) is of a 

 grayish color, circular in form, about 4 mm. or ^ inch in diameter. 



Branches of Communication. To this ganglion the accessory portion of the 

 spinal accessory nerve is connected by several delicate filaments; it also communi- 

 cates by a twig with the petrous ganglion of the glossopharyngeal, with the facial 

 nerve by means of its auricular branch, and with the sympathetic by means of 

 an ascending filament from the superior cervical ganglion. 



The ganglion of the trunk or the inferior ganglion (ganglion nodosum) is a 

 plexiform cord, cylindrical in form, of a reddish color, and about an inch (2 cm.) 

 in length; it involves the whole of the fibres of the nerve, and passing through it 

 is the vagal accessory portion of the spinal accessory nerve, which blends with 

 the vagus below the ganglion, to be then continued principally into its pharyngeal 

 and superior laryngeal branches. 



Branches of Communication. This ganglion is connected with the hypoglossal, 

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

 and second cervical nerves. 



Branches of Distribution. The branches of the vagus are: 



In the jugular fossa . j Meningeal or dural. 



( Auricular. 



| Pharyngeal. 

 In the neck J Superior laryngeal. 



I Recurrent laryngeal. 



I Cervical cardiac. 



( Thoracic cardiac. 



In the thorax .... \ Anterior or ventral pulmonary. 



Posterior or dorsal pulmonary. 



v (Esophageal. 

 In the abdomen .... Gastric. 



The Meningeal or Dural Branch (ramus meningeus) is a recurrent filament 

 given off from the ganglion of the root on the jugular foramen. It passes back- 

 ward, and is distributed to the dura lining the posterior fossa of the base of the 

 skull. 



The Auricular Branch or Arnold's Nerve (ramus auricularis) (Fig. 745) arises 

 from the ganglion of the root, and is joined soon after its origin by a filament 

 from the petrous ganglion of the glossopharyngeal ; it passes outward behind the 

 jugular vein, and enters a small canal on the outer wall of the jugular fossa. 

 Traversing the substance of the temporal bone, it crosses the facial canal or 

 aquaeductus Fallopii about 4 mm. ( inch) above its termination at the stylo- 

 mastoid foramen; here it gives off an ascending branch, which joins the facial. 

 The continuation of the nerve reaches the surface by passing through the auricular 

 fissure between the mastoid process and the external auditory meatus, and divides 



