412 ANATOMY IN A NUTSHELL. 



mis. stomach, and heart. It is the longest of all the cranial nerves. Its super- 

 ficial origin is from the groove between the olivary and restiform bodies below 

 that <>f the glosso-pharyngeal nerve by eight or ten fasciculi (Plate CLXXXVII). 

 Its deep origin is in the floor of the fourth ventricle from the nucleus vagi 

 beneath the ala cinerea below ami continuous with the nucleus of origin of the 

 glosso-pharyngeal. The origin of the sensory fibers of the tenth nerve is in the 

 ganglion of the root and the ganglion of the trunk. Van Gehuchten says that 

 the only sensory nucleus of the tenth is in the fasciculus solitarius. The nerve 

 now passes over the flocculus to the middle compartment of the jugular fora- 

 men, passing behind the glosso-pharyngeal in the same sheath with the spinal 

 accessory. After leaving the jugular foramen it is connected with the accessory 

 part of the spinal accessory and has an enlargement called the ganglion of the 

 trunk. The accessory part of the spinal accessory nerve sends most of its branches 

 into the pharyngeal and superior laryngeal branches of the tenth, while some of 

 its fibers join the ganglion of the trunk. The tenth nerve now passes down the 

 neck in the carotid sheath to the root of the neck. This sheath contains the in- 

 terna] jugular vein externally, the common carotid artery internally, and the 

 tenth nerve between them but on a plane posterior. The relations of this 



SHEATH ARE AS FOLLOWS: 



Ix Front. — A few filaments descending from the loop of communication 

 between the descendens and communicans hypoglossi. 



Behind. — (1) The inferior thyroid artery, (2) The recurrent laryngeal 

 nerve. (3) The sympathetic nerve. 



On the inner side. — (1) Trachea, (2) Thyroid gland, (3) Lower part of 

 the larynx (more prominent in the female). 



The ganglion of the root is a small gray mass about five millimetres in 

 diameter and is situated in the jugular foramen. It is connected with the 

 superior cervical ganglion of the sympathetic and the spinal accessory nerves. 

 It gives off an auricular branch by which it is connected with the facial and the 

 glosso-pharyngeal nerves. It also gives off a recurrent meningeal branch. 



The ganglion of the trunk is below the base of the skull and in front of the 

 internal jugular vein and is about seventeen millimetres long. It is connected 

 with the accessory part of the spinal accessory nerve, with the hypoglossal nerve, 

 ami with the superior cervical ganglion of the sympathetic, and with the loop 

 between the firsl and second cervical nerves. The branches it gives off are (1) 

 a pharyngeal, (2) a superior laryngeal, (3) a superior cardiac (Plates CCXXII- 

 ( (XX I II. 



The right pneuinogastric nerve passes downward between the first part of 

 the subclavian artery and the subclavian vein beside the trachea, behind the 

 righl innominate vein, and behind the root of the right lung. It helps to form 

 the posterior pulmonary plexus. It now passes downward in two cords which 

 run on the oesophagus and communicate with the pneumogastric nerve of the 

 opposite side making the oesophageal plexus. The two divisions of the 

 pneumogastric nerve mute into one trunk behind the (esophagus and passing 

 through the oesophageal opening in the Diaphragm, is distributed to the pos- 

 terior surface ot' the stomach and to the solar plexus and its divisions. 



