nu: <;I;I:.\T sYMr.iTiii"rn' \i-:n\-nrs SYSTEM. T-',. 



I?ut sometimes, also, this rnmuscule cannot bo distinguished, and the sub- 

 1 cord serins to bo abruptly terminated by the filament of com- 

 munication from the last sacral pair. 



FUNCTIONS. The functions of the sympathetic are yet but little known, 

 notwithstanding the labours of many physiologists, at whose head must bo 

 placed Claude Bernard. In a physiological condition, this nerve possesses 

 an extremely obscure sensibility, but which may become very acute in 

 pathological cases. It conveys to organs the unconscious motor exci- 

 tations originating in the spinal cord; and through the filaments it 

 furnishes to the vessels the vaso-motor nerves it holds under its control 

 the circulatory phenomena, especially in the capillary plexuses, causing 

 these canals to dilate or contract, and thus diminish or accelerate the flow 

 of blood in them. By this action on the blood-vessels, it may have a 

 secondary influence on the nutrition of the organs to which these vessels 

 arc distributed. 



DIFFERENTIAL CHARACTERS IN THE GREAT SYMPATHETIC OF OTHER THAN 

 SOUPED ANIMALS. 



In all the domesticated mammals, the general disposition of the great sympathetic is 

 very similar; so that there are but few and slight differences to note. 



In the Or, the cervical filament does not arise from the lower extremity of the 

 superior ganglion, but from its middle portion ; it is divisible into two or three filaments 

 fr a certain d'stnu-e, after which it lies beside the pncumogiistric. The rumubcule 

 that leavt-s the lower end of the cervical g.mglion is very large, and reaches the division 

 of the common carotid; that which accompanies the internal c-arotid artery is also of a 

 considerable size. (Ruminants have 13 thoracic and 6 lumbar ganglia.) 



In the Dog, the cervical sympathetic cord is closely united with the pnenmogastric, 

 nnd it is not possible to separate them from each other, as can be done in Solipeds and 

 Ruminants. (In the Carnivora there are 13 thoracic and 7 lumbar ganglia.) 



The 1'i'j has a superior cervical ganglion, which is fusiform and very long ; at its 

 lower extremity it gives off several filaments, one of which lies beside the pneumogastric 

 in the cervical region, but separates from it to join the middle cervical ganglion; the 

 - pa>s to the tenth nerve, and are confounded with it at the g-.mgliouic enlargement 

 it shows In-hind tho pharynx. At the entrance- to the chest, a branch separates from 

 the pneunn'ira.-tric, passes along with the axillary arteries, and finally enters the heart. 

 This branch is perhaps formed by the filaments of the sympathetic that joined tho 

 pneumogastric at the upper part of the neck. (The inferior cervical ganglion, according 

 t" I., yh. is completely isolated from the thoracic ganglion. The Pig has H thoracic 

 and 7 lumbar ganglia.; 



COMPARISON OF THE GREAT SYMPATHETIC OF MAN WITH THAT OF ANIMALS. 



It is divided ami disposed as in animals. The cervical portion is composed of a 



superior fusiform ganglion, from which emerge many branches which have been studied 



with the greatest eare. Tln-r.- ar- .l.-.-ril.. -.1 : l. Superior or intercraniul branches ; 2, 



al or anastomosing branches with the first four spinal nerves; 3, Internal or 



al branches, which mix with the pharyngeal and laryngeal filaments of the 



pin iimogastric ; 4, Anterior or external camtidt-al liram-hes. which pass t> the common 



carotid and the middle of a small ganglion, the inten-arotid; 5, Posterior, muscular, or 



osseous branches. All these are present in tho Hors< . A < -r\ieal tilament and twu 



inferior ganglia middle and inferior complete this region, of which there is nothing 



mop- l lx- .-aid. 



The thi >racic portion is absolutely identieiil in it.- di-]*isition with that of animals; it 

 gives rise to a great splanchnic nerve, and terminates in the scrnilmmr ganglia. 



Then,- are no differences to note in the Itimlmr and sacral poiHottt, which we have 

 , d as the pelvic. 



