THE CONNECTING AND OTHER BRANCHES OF THE VAGUS. 607 



scriptorius (fig. 427, 10) [and it is very probably the representative of the cells of the vesicular 

 column of Clarke ( 366)]. (2) Other fibres come from the "longitudinal bundle" or 

 u respiratory bundle " lying outside the nucleus, and reaching down into the cervical enlarge- 

 ment. (3) A motor nucleus the nucleus ambiguus a prolongation of some of the cells of the 

 anterior horn of the spinal cord, gives some motor fibres. It leaves the medulla oblongata by 

 10 to 15 threads behind the 9th nerve, between the divisions of the lateral column, and has a 

 ganglion (jugular) upon it in the jugular foramen (fig. 428, VIII). Its branches contain 

 fibres which subserve different functions. 



1. The sensory meningeal branch from the jugular ganglion accompanies the 

 vaso-motor fibres of the sympathetic on the middle meningeal artery, and sends 

 fibres to the occipital and transverse sinus. 



When it is irritated, as in congestion of the head and inflammation of the dura mater, it gives 

 rise to vomiting. 



2. The auricular branch (fig. 433, au.) from the jugular ganglion receives a 

 communicating branch from the petrous ganglion of the 9 th nerve, traverses the 

 canaliculus mastoideus, crossing the course of the facial, with which it exchanges 

 fibres whose function is unknown. On its course, it gives sensory branches to 

 the posterior part of the auditory meatus, and the adjoining part of the outer ear. 

 A branch runs along with posterior auricular branch of the facial, and confers 

 sensibility on the muscles. 



"When this nerve is irritated, either through inflammation or by the presence of foreign 

 bodies in the outer ear passage, it may give rise to vomiting. Stimulation of the deep part of 

 the external auditory meatus in the region supplied by the auricular branch causes coughing 

 reflexly [e.g., from the presence of a pea in the ear]. Similarly, contraction of the blood-vessels 

 of the ear may be caused, reflexly {Snellen, Loven). 



The nerve is the remainder, of a considerable branch of the vagus which exists in fishes and 

 the larvae of frogs, and runs under the skin along the side of the body. 



3. The connecting branches of the vagus are : (1) A branch which directly 

 connects the petrous ganglion of the 9th with the jugular ganglion of the 10th ; 

 its function is unknown. (2) Directly above the plexus gangliiformis vagi, the 

 vagus is joined by the whole inner half of the spinal accessory. This nerve conveys 

 to the vagus the motor fibres for the larynx, and the cervical part of the oesophagus 

 (which according to Steiner lie in the inner part of the nerve-trunk), as well as the 

 inhibitory fibres for the heart (CL Bernard). (3) The plexus gangliiformis fibres, 

 whose function is unknown, join the trunk of the vagus from the hypoglossal, 

 superior cervical ganglion of the sympathetic, and the cervical plexus. 



4. Pharyngeal Plexus. The vagus sends one or two branches (fig. 433, 2) from 

 the upper part of the plexus gangliiformis to the pharyngeal plexus, where at the 

 level of the middle constrictor of the pharynx, it is joined by the pharyngeal branches 

 of the 9th nerve and those of the upper cervical sympathetic ganglion, near the 

 ascending pharyngeal artery, to form the pharyngeal plexus. The vagal fibres in 

 this plexus supply the three constrictors of the pharynx with motor fibres, while the 

 tensor palati (Otic ganglion, 347, III.) and levator of the soft palate (compare 

 Spheno-palatine ganglion, 347, II.) also receive motor (? sensory) fibres. Sensory 

 fibres of the vagus from the pharyngeal plexus supply the pharynx from the part 

 beneath the soft palate downwards. These fibres excite the pharyngeal constric- 

 tors reflexly, during the act of swallowing ( 156). If stimulated very strongly, 

 they may cause vomiting. (The sympathetic fibres of the oesophageal plexus give 

 vaso-motor nerves to the oesophageal vessels ; for the oesophageal branches of the 

 9th nerve see above.) 



5. The vagus supplies two branches to the larynx, the superior and inferior 

 laryngeal. 



(a) The superior laryngeal (fig. 433, 3) receives vaso-motor fibres from the 

 superior cervical ganglion of the sympathetic. It divides into two branches, external 

 and internal : (1) The external branch receives vaso-motor fibres from the same 

 source (they, accompany the superior thyroid artery), and supply the crico-thyroid 



