262 



THE CRANIAL NERVES. 



accessory nerve, and its filaments unite in a small gang-Home enlargement which is 

 known as the ganglion of the root of the pneumo-gastric. After its passage through 

 the foramen, it is joined by the accessory part of the spinal accessory nerve, and a 

 second ganglion is formed upon it, the ganglion of the trunk of the nerve. Several 

 communications are at the same time established with surrounding nerves. 



The upper ganglion or ganglion of the root of the pneumo-gastric nerve 

 i ganglion jugular e), situated in the jugular foramen, is of a greyish colour, nearly 

 spherical, and about 4 mm. in diameter. It has filaments connecting it with other 

 nerves, viz., with the facial, the petrosal ganglion of the glosso-pharyngeal, the spinal 

 accessory, and the sympathetic. 



The lower ganglion or ganglion of the trunk of the pneumo-gastric nerve 

 (cervical ganglion, ganglion nodoswri) is placed below the base of the skull, about 

 1 cm. beyond the upper ganglion. It is of a flattened cylindrical form and reddish 

 colour, and measures from 15 to 20 mm. in length and 4 in breadth. The 



nX't 



C.r. 



Fig. 178. SECTION OF THE BULB AT ABOUT THE 

 MIDDLE OP THE OLIVE. (Schwalbe. ) 



The full description of this figure will be found 

 at p. 54 of parti. The following numbers refer 

 to the vagus and hypoglossal nerves and their 

 connections : n X, n X', two parts of the vagal 

 nucleus; f.s., funiculus solitarius ; n. am, 

 nucleus ambiguus or accessory vagal nucleus ; 

 X, bundle of vagus emerging between the resti- 

 form body and the olive ; n. XII, hypoglossal 

 nucleus ; XII, bundle of hypoglossal nerve 

 emerging between the olive and the pyramid. 



accessory part of the spinal accessory 

 nerve runs over the surface of the 

 ganglion, and is in part continued 

 directly into the pharyngeal and 

 superior laryngeal branches of the 

 vagus ; some of the accessory fibres, 

 however, become incorporated with the 

 main trunk, and enter the inferior 

 laryngeal and cardiac branches. The 



lower ganglion communicates with the hypoglossal, the spinal, and the sympathetic 

 nerves. 



The nerve-cells in both ganglia of the vagus belong to the unipolar or spinal 

 type. 



The pneumo-gastric nerve descends in the neck between, and concealed by, the 

 internal jugular vein and the internal carotid artery, and afterwards similarly between 

 the vein and the common carotid artery, being enclosed along with them in the 

 sheath of the vessels. In their passage into and through the thorax, the nerves are 

 disposed differently on the right and left sides. 



On the right side the nerve crosses over the first part of the right subclavian 

 artery at the root of the neck, and its recurrent laryngeal branch turns backwards 

 and upwards round that vessel. The nerve then enters the thorax behind the right 

 innominate vein, and descends on the side of the trachea to the back of the root of 

 the lung, where it spreads out in the posterior pulmonary plexus. It emerges from 

 this plexus in the form of two cords, which are directed to the oesophagus, and by 

 their union and subdivision on it form, with similar branches of the left nerve, the 

 oesophageal plexus. Xear the lower part of the thorax, the branches of the nerve, 

 which have thus interchanged fibres w r ith the nerve of the left side, are gathered 



