SYMPATHETIC NERVE. 



427 



the supposed communication between the 

 sympathetic and pituitary body in mammals 

 and birds, but failed to convince himself that 

 any such communication exists, (e) Arterial 

 branches, accompanying the branches of the 

 internal carotid arteries. These are described 

 by Chaussier* and Ribes as passing not only 

 along the anterior and middle cerebral arteries, 

 but also along the branches of the ophthalmic 

 artery, forming minute plexuses upon them. 

 One of these plexuses is described by these 

 authors, as well as by Rusel-j- and Langenbeck, 

 as accompanying the central artery of the 

 retina into the eyeball. Ribes has also traced 

 filaments from the cavernous plexus upon the 

 anterior communicating arteries, by means of 

 which the sympathetic cords of either side 

 are united, there being at their point of 

 junction a small ganglionic enlargement ; this 

 arrangement has been denied by Lobstein and 

 others. 



3. External Carotid Plexus. The external 

 carotid plexus formed as already mentioned 

 by the union of the nervi molles from the su- 

 perior cervical ganglion, commences at the 

 origin of the external carotid artery. There 

 is sometimes a ganglionic enlargement present, 

 which from the fact of being situated at the 

 point of bifurcation of the common carotid 

 artery, was termed by Arnold the intercaro- 

 tidean ganglion. The external carotid plexus 

 extends along the artery of the same name, 

 encircling it with numerous branches, on 

 which frequently occur small ganglionic en- 

 largements. At its commencement numerous 

 communications are formed between it and 

 the branches of the glosso-pharyngeal and 

 vagus nerves, which go to form the pharyngeal 

 plexus. It also forms connections with the 

 upper cardiac nerve, and, higher up, as it 

 passes with the artery through the parotid 

 gland, branches are given off for the supply of 

 this organ, and also others, which become 

 connected with the facial and auriculo-tem- 

 poral nerves. Offsets are sent from it along 

 the divisions of the external carotid artery, 

 forming a number of plexuses around them, 

 which are named according to the arterial 

 branches which they accompany. One of 

 these accompanies the superior thyroid artery 

 into the substance of the thyroid gland : it 

 communicates with the superior laryngeal and 

 upper cardiac nerves. Another accompanies 

 the ascending pharyngeal artery, and is inti- 

 mately connected with the pharyngeal plexus. 

 The lingual plexus encircles the artery of the 

 same name, giving off filaments to the sub- 

 lingual gland, and forming communications 

 with the lingual branches of the glosso-pha- 

 ryngeal nerve. The facial plexus surrounds 

 the facial artery and its branches, one or two 

 filaments, which accompany the submental 

 artery, pass to the submaxillary gland, and 



* Memoires de la Societe Me'd. d'Emulation, 

 vol. vii. p. 97, 



f Tiedemann's Zeitsclirift. fur Physiol. baud ii. 

 p. 227. 



communicate with the ganglion of the same 

 name. Small plexuses accompanying the occi- 

 pital and posterior auricular arteries seem to 

 terminate chiefly in the parotid gland. Most 

 of the branches which accompany the super- 

 ficial temporal artery appear to pa'ss along the 

 arteries going to the ear and eyelids. Nu- 

 merous filaments, presenting here and there 

 ganglionic enlargements, proceed upwards on 

 the external carotid artery as far as its divi- 

 sion into the temporal and internal maxillary 

 arteries ; many of these appear to terminate 

 in the parotid gland, while others accompany 

 the temporal and internal maxillary arteries. 

 Of the latter, one is described by Arnold as 

 emanating from the plexus surrounding the 

 middle meningeal artery, and passing to the 

 posterior part of the otic ganglion. Subsidiary 

 branches accompany the different divisions of 

 the internal maxillary artery. 



From the external carotid plexus several 

 filaments pass downwards upon the common 

 carotid artery, forming, with others derived 

 from the middle cervical ganglion, a plexus 

 around the vessel, which accompanies it and 

 forms communications with the inferior thyroid 

 plexus, as well as with the superior cardiac 

 nerve and cardiac plexus. 



B. Thoracic Plexuses of the Sympathetic. 

 The plexuses occurring in the thorax in con- 

 nection with the sympathetic are the cardiac 

 plexus, and the plexus surrounding the 

 thoracic aorta : it also contributes to the 

 formation of the pulmonary and oesophageal 

 plexuses. 



1. Cardiac Plexus. The cardiac plexus is 

 formed by the union of the cardiac branches 

 of the sympathetic already described, and by 

 numerous filaments derived from the recurrent 

 laryngeal, as well as from the vagus nerve it- 

 self; a branch from the descendens noni nerve 

 accompanies the superior cardiac nerve, and 

 also terminates in the plexus. The superior 

 cardiac nerves, the branches from the recurrent 

 laryngeal and vagus nerves terminate in the 

 upper part of the plexus ; the middle cardiac 

 branches of both sides terminate commonly 

 in its middle portion, while the inferior cardiac 

 branches, with some of those derived from 

 the recurrent laryngeal nerve, end chiefly in 

 its lower part. The plexus is asymmetrical, 

 and is situated in the upper part of the tho- 

 racic cavity, extending from the transverse 

 portion of the arch of the aorta to the base 

 of the heart : it consists of a widely-meshed 

 network of moderately fine filaments, some 

 presenting a greyish, others a more or less 

 white appearance. About the centre of the 

 plexus, behind the arch of the aorta and in 

 front of the bifurcations of the trachea, at 

 the point of division of the pulmonary artery 

 there is commonly present a ganglionic en- 

 largement. This which is termed the cardiac 

 ganglion (Ganglion cardiacum Wrisbergii), 

 presents a greyish colour and irregular shape, 

 generally more or less angular or oblong, and 

 measures from one to two lines in length. 

 That portion of the cardiac plexus which is 



