984 THE NERVOUS SYSTEM 



millimetres in diameter which lies in the jugular foramen (fig. 706). It is connected 

 with the spinal accessory nerve and with the superior cervical sympathetic ganglion, 

 and it gives off an auricular branch, by means of which it becomes connected with the 

 facial and glosso-pharyngeal nerves, and a recurrent meningeal branch. 



The Ganglion Nodosum (Ganglion of the Trunk) lies below the base of the skull 

 and in front of the upper part of the internal jugular vein. It is of flattened ovoid 

 form and about seventeen millimetres long and four millimetres broad (figs. 706 and 

 707). It is connected with the accessory part of the eleventh nerve, with the twelfth 

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

 between the first two cervical nerves, and it gives off a pharyngeal, a superior laryn- 

 geal, and a superior cardiac branch. 



Communications. The vagus nerve is connected with the ninth, eleventh, and 

 twelfth nerves, with the sympathetic, and with the loop between the first and second 

 cervical nerves. 



(1) Two communications exist between the tenth and ninth nerves: one between 

 their trunks, just below the base of the skull, and one, in the region of their ganglia, 

 consisting of one or two filaments. When two filaments are present one passes from 

 the jugular ganglion and the other from the auricular nerve to the petrous ganglion 

 of the glosso-pharyngeal nerve. Either or both of these filaments may be absent. 



(2) Two twigs pass- from the eleventh nerve to the ganglion nodosum, and at a 

 lower level the accessory part of the eleventh nerve also joins the same ganglion 

 (fig. 706). The majority of the fibres of the accessory part of the eleventh nerve 

 merely pass across the surface of the ganglion and are continued into the pharyngeal 

 and superior laryngeal branches of the vagus, but a certain number blend with the 

 trunk of the vagus and are continued into its recurrent laryngeal and cardiac branches. 



(3) Two or three fine filaments connect the ganglion nodosum with the twelfth 

 nerve as the latter turns around the lower part of the ganglion (fig. 706). 



(4) Fibres pass from the superior cervical ganglion of the sympathetic to both 

 ganglia of the vagus (fig. 706). 



(5) A twig sometimes passes from the loop between the first two cervical nerves 

 to the ganglion nodosum (fig. 706). 



Terminal Branches. These are the meningeal, auricular, pharyngeal, superior 

 laryngeal, inferior laryngeal, cardiac, bronchial, pericardia!, oesophageal, and the ab- 

 dominal branches. 



(1) The meningeal or recurrent branch is a slender filament which is given 

 off from the jugular ganglion. It takes a recurrent course through the jugular 

 foramen, and is distributed to the dura mater around the transverse (lateral) sinus. 



(2) The auricular branch, or nerve of Arnold, arises from the jugular ganglion 

 in the jugular foramen. It receives a branch from the petrous ganglion of the 

 glosso-pharyngeal, enters the petrous part of the temporal bone through a fora- 

 men in the outer wall of the jugular fossa, and communicates with the facial nerve 

 or merely lies in contact with it as far as the stylo-mastoid foramen. It usually 

 leaves the temporal bone by the stylo-mastoid foramen, but it may pass through the 

 tympano-mastoid fissure, and it divides, behind the pinna, into two branches, one of 

 which joins the posterior auricular branch of the facial while the other supplies sen- 

 sory fibres to the posterior and inferior part of the external auditory meat us and the 

 back of the pinna. It also supplies t \vigs to the osseous part of the external auditory 

 meatus and to the lower part of the outer surface of the membrana tympani. 



(3) The pharyngeal branches may be two or three in number. The principal 

 of these joins the pharyngeal branch of the glosso-pharyngeal on the outer surface 

 of the internal carotid artery, and after passing with the latter internal to the exter- 

 nal carotid artery it turns downwards and inwards to reach the posterior aspect 

 of the pharynx. Here the two nerves are joined by branches from the superior cervi- 

 cal ganglion of the sympathetic, with which they form the pharyngeal plexus 

 (figs. 706 and 707). Branches from this plexus supply sensory fibres to the mucous 

 membrane of the pharynx and motor fibres to the constrictores pharyngis, levator 

 palatini, uvulae, glosso-palatinus. and pharyngo-palatinus. 



(4) The superior laryngeal nerve arises from the lower part of the ganglion 

 nodosum, and passes obliquely downwards and inwards behind and internal to both 

 internal and external carotid arteries towards the larynx. In this course it describes 

 a curve with the convexity downwards and outwards and divides into (i) a larger in- 

 ternal and (ii) a smaller external branch (fig. 706). Before its division it is joined 



