120 INNERVATION. [CHAP. XX. 



nerve, with the cervical plexus, and with the superior cervical gan- 

 glion, in a manner sometimes very intimate. 



The following branches are given off by the vagus nerve. 



1. The Pharyngeal Branch. This is believed by some anatomists 

 to be derived altogether from the spinal accessory nerve, through 

 its anastomosis with the vagus. It forms, along with the glosso- 

 pharyngeal, some cervical nerves, and sympathetic filaments, the 

 pharyngeal plexus, and its branches seem to be distributed to the 

 muscle of the pharynx. Sometimes there are two pharyngeal 

 branches, a superior and inferior. 



2. The Superior Laryngeal Nerve, which gives off the external 

 laryngeal nerve to the crico-thyroid muscle, and is itself distributed 

 to the mucous membrane of the larynx, and sends an anastomotic 

 branch to the inferior laryngeal nerve. 



3. Cervical Cardiac Branches. These are at least two in number 

 on each side, and they pass down in front of the innominata on 

 the right and of the aortic arch on the left, and contribute to form 

 the small plexus between the aorta and pulmonary artery. 



4. The Inferior Laryngeal Nerve. This important nerve is dis- 

 tributed to all the intrinsic muscles of the larynx, except the crico- 

 thyroid. The peculiarity of its course has given it the name recur- 

 rent. It has interesting relations differing on the right and left side. 

 Arising on the left side just in front of the arch of the aorta, it 

 winds round the concavity of that vessel, and ascends between the 

 oesophagus and the trachea to the lower edge of the inferior con- 

 strictor of the pharynx. The nerve of the right side separates from 

 the trunk just above the subclavian artery, and winds round it, 

 ascending in the neck to a similar destination. 



Both recurrent nerves before their ultimate distribution give off 

 filaments to the heart, to the trachea, to the ossophagus, and to the 

 inferior constrictor of the pharynx. 



5. Inferior or Thoracic Cardiac Branches, distributed to the peri- 

 cardium, and the cardiac plexus. 



6. Anterior Pulmonary Branches, passing in front of the bronchial 

 tube at the root of the lung, and penetrating the pulmonary 

 substance, along with the ramifications of the bronchus, and of the 

 pulmonary artery. 



7. (Esophageal Branches, which are very numerous, and distri- 

 buted to the oesophagus, throughout its entire length. 



8. Tracheal Branches, to the mucous membrane and muscular 

 fibres of the trachea. 



9. Posterior Pulmonary Branches ; these go to form the posterior 



