PAR VAGUM. 503 



back part of the larynx and the contiguous surface of the 

 pharynx. 



There is a difference in the arrangement of the recurrentsyon 

 the different sides, in consequence of one winding round the 

 aorta, while the other winds round the subclavian artery. 



The superior laryngeal nerve is the proper nerve of sensa- 

 tion to the larynx, and is chiefly distributed on its mucous mem- 

 brane. The recurrent is the nerve of motion to this organ, and, 

 as above described, is mainly spent upon its muscles. 



After sending off the recurrents, each trunk of the Par 

 Vagum proceeds behind the ramifications of the trachea ; but 

 previously detaches some small branches, which are joined by 

 twigs from the intercostal and from the recurrent, and form a 

 plexus upon the anterior part of the vessels going to the lungs. 

 This Anterior plexus, after sending off some minute branches 

 to the cardiac nerves and the pericardium, transmits its branches 

 with the bronchia and the blood-vessels, into the substance of 

 the lungs. 



Some of the branches which proceed from the par vagum, 

 pass down on the posterior part of the trachea, and enter into 

 the membrane which forms it, and the mucous glands which are 

 upon it ; and some pass to the oesophagus. 



When the par vagum is behind the great vessels of the lungs, 

 a number of branches go off transversely, and are also joined 

 by some fibres from the sympathetic. These form the Posterior 

 pulmonary plexus ; the ramifications from which proceed into 

 the substance of the lungs, and are principally spent upon 

 the ramifications of the bronchia. It has been said,* that the 

 small twigs into which they divide, very generally penetrate 

 into the small ramifications of the bronchia, and are spent 

 upon their internal membrane. The branches of the posterior 

 pulmonary plexus are more numerous than those of the 

 anterior. 



Soon after sending off the nerves of the pulmonary plexus, 

 the Par Vagum proceeds downwards upon the oesophagus ; 

 the left nerve being situated anteriorly, and the right posteri- 



* See Buisson, in the continuation of the Descriptive Anatomy of Bichat. 



