956 THE NERVOUS SYSTEM 



The jugular ganglion (ganglion of the root) is a spherical grey mass about 

 five millimetres in diameter which lies in the jugular foramen (fig. 744). It is 

 connected with the spinal accessory nerve and with the superior cervical sympa- 

 thetic ganglion, and it gives off an auricular branch, by means of which it becomes 

 associated 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. 744 and 743). It is joined by the accessory part of the spinal accessory 

 nerve, and is associated with the hypoglossal 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 laryngeal, and a superior cardiac 

 branch. Both ganglia and especially the nodosal retain numerous cell-bodies of 

 sympathetic neurones and the twigs issuing from the ganglia thus contain sympa- 

 thetic fibres. The greater part of the cell-bodies are of sensory neurones. 



Communications. — ^The vagus nerve is connected with the glosso-pharyngeal, 

 spinal accessory and hypoglossal nerves, with the sympathetic, and with the loop 

 between the first and second cervical nerves. 



(1) Two communications exist between the vagus and glosso-pharyngeal nerves: one 

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

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

 ganghon and the other from the auricular nerve to the petrosal gangUon of the glosso-pharyngeal 

 nerve. Either or both of these filaments may be absent. 



(2) Two twigs pass from the spinal accessory nerve to the gangUon nodosum, and at a 

 lower level the accessory part of the spinal accessory nerve also joins the same ganghon (fig. 

 744). The majority of the fibres of the accessory part of the spinal accessory 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 ganghon nodosum with the hypoglossal nerve 

 as the latter turns around the lower part of the ganghon (fig. 744). 



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

 of the vagus (fig. 744). 



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

 ganghon nodosum (fig. 744). 



Terminal branches. — ^These are the meningeal, auricular, pharyngeal, superior 

 laryngeal, recurrent (inferior laryngeal), cardiac, bronchial, pericardial, oesopha- 

 geal, and the abdominal 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 ganghon in the jugular 

 foramen. It receives a branch from the petrosal ganglion of the glosso-pharyngeal, enters the 

 petrous part of the temporal bone through a foramen in the lateral 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 

 sensory fibres to the posterior and inferior part of the external auditory meatus and the back 

 of the pinna. It also supplies twigs to the osseous part of the external auditory meatus and 

 to the lower part of the outer surface of the tympanic membrane. 



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

 joins the pharyngeal Ijranch of the glosso-pharyngeal on the lateral surface of the internal car- 

 otid artery, and after passing with the latter medial to the external carotid artery it turns 

 downward and medialward to reach the posterior aspect of the pharynx. Here the two nerves 

 are joined by branches from the .superior cervical ganglion of the sympathetic, with which they 

 form the pharyngeal plexus (figs. 743, 744). Branches from this plexus supply sensory fibres 

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

 palatini, uvuhe, glosso-palatinus, and pharyngo-i)!ilatinus. 



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

 nodosum, and passes (jbliciuely downward and medialward behind and medial to 

 both internal and ext(!rnal carotid arteries toward the larynx. In this course it 

 describes a curve with the convexity downward and lateralward and divides into 

 (i) a larger internal and (ii) a smaller external branch (fig. 744). Before its 

 division it is joined by twigs with the sympathetic and with the pharyngeal plexus, 

 and it gives a small branch to the internal carotid artery. 



