THE TENTH, VAGUS, OR PNEUMO GASTRIC NERVE 



into two branches, one of which communicates with the posterior auricular nerve, 

 while the other supplies the integument at the back part of the pinna and the 

 posterior part of the external auditory meatus. 



The Pharyngeal Branch (ramus pharyngeus), the principal motor nerve of the 

 pharynx, arises from the upper part of the ganglion of the trunk of the vagus. 

 It consists principally of filaments from the vagal accessory portion of the spinal 

 accessory nerve; it passes across the internal carotid artery to the upper border 

 of the Middle constrictor of the pharynx, where it divides into numerous filaments 

 which join with those from the glossopharyngeal the superior laryngeal (its 

 external branch), and sympathetic, to form the pharyngeal plexus (plexus pharyn- 

 geus), from which branches are distributed to the muscles and mucous membrane 

 of the pharynx and the muscles of the soft palate, except the Tensor palati. From 

 the pharyngeal plexus a minute filament is given off, which descends and joins 

 the hypoglossal nerve as it winds around the occipital artery. 



TO EXTERNAL AUDITORY 



MEV|US AND 

 \(OF 



ARNOLDS FORAMEN 



TO POSTERIOR 



AURICULAR OF 



FACIAL 



OSSOPHARYNGEAL 



AURICULAR BRANCH 

 OF VAGUS 



ARTERIOSUS 



FIG. 745. Plan of Arnold's nerve. (W. Keiller.) 



FIG. 746. Relations of vagus and recurrent laryn- 

 geal nerves to the great vessels. (W. Keiller.) 



The Superior Laryngeal Nerve (n. laryngeus superior) (Figs. 743 and 744) is 

 larger than the preceding, and arises from the middle of the ganglion of the 

 trunk of the vagus. In its course it receives a branch from the superior cervical 

 ganglion of the sympathetic. It descends by the side of the pharynx behind the 

 internal carotid artery, where it divides into two branches, the external and internal 

 laryngeal. 



The external laryngeal branch (ramus externus] (Fig. 744), the smaller, descends 

 by the side of the larynx, beneath the Sternothyroid, to supply the Cricothyroid 

 muscle. It gives branches to the pharyngeal plexus and the Inferior constrictor, 

 and communicates with the superior cardiac nerve, behind the common carotid. 



The internal laryngeal branch (ramus interims) descends to the opening in the 

 thyrohyoid membrane, through which it passes with the superior laryngeal artery, 

 and is distributed to the mucous membrane of the larynx. A small branch com- 

 municates with the recurrent laryngeal nerve. The branches to the mucous 

 membrane are distributed, some in front to the epiglottis, the base of the tongue, 

 and the epiglottidean glands; while others pass backward, in the arytenoepi- 

 glottidean fold, to supply the mucous membrane surrounding the superior orifice 

 of the larynx, as well as the membrane which lines the cavity of the larynx as 

 low down as the vocal cord. The filament which joins with the recurrent laryn- 



64 



