SYMPATHETIC NERVE. 



445 



course. The communicating branch between 

 the carotid plexus and the sixth nerve, and 

 the deep or carotid branch of the vidian, 

 were regarded as the roots by which the 

 nerve commenced, while the different branches 

 passing between it and the other cerebral and 

 spinal nerves, were believed also to be entirely 

 composed of fibres sent by the latter to the 

 sympathetic. 



According to Bichat, the sympathetic is an 

 independent system of nerves ; the cords which 

 pass between it and the cerebral and spinal 

 nerves are not entirely composed of fibres 

 sent to the sympathetic, but are partly 

 branches transmitted by it to these nerves. 



The observations of Petit and Fontana* had 

 already shown that the communication be- 

 tween the sixth nerve and the sympathetic 

 did not consist of fibres sent by the former 

 to the latter, inasmuch as the sixth nerve 

 was found to be thicker beyond the point of 

 junction with the filament than before. 



In 1827 Retziusf showed that in the tri- 

 facial nerve in the horse there was present 

 a gray fasciculus of fibres distinct from the 

 white, and which seemed to take its origin in 

 the ganglion. Somewhat similar observations 

 were made by Varrentrap and Miillcr on the 

 branches of the trigeminus, and by Giltay on 

 the glosso-pharyngeal, vagus, and superior 

 spinal nerves of the fish, &c. It was after- 

 wards noticed by Remak that the gray por- 

 tions of the communicating branches con- 

 sisted of fibres which were sent by the 

 sympathetic to the cerebro-spinal nerves to 

 be distributed peripherically with them. On 

 microscopic examination it was found by him 

 that the sympathetic contained a large num- 

 ber of fibres presenting a peculiar structure : 

 these he regarded as the proper organic or 

 sympathetic nerve fibres, and believed that 

 while the sympathetic derived from the brain 

 and spinal cord all the tubular fibres con- 

 tained in it, the grayer portions of the rami 

 commurdcantes were composed of organic 

 or sympathetic fibres, which were sent by 

 the sympathetic to the cerebro-spinal nerves, 

 to be distributed peripherically with them. 

 The same view was also adopted by Miiller 

 and others. Valentin, as has been already 

 stated, rejecting the fibres of Remak as being 

 destitute of the properties of nerve-fibres, 

 believed that the rami commimicantcs con- 

 sisted entirely of fibres sent by the brain and 

 spinal cord to the sympathetic. Volkrnann 

 and Bidder, though agreeing with Valentin 

 in regard to the fibres of Remak, still main- 

 tained the opinion, that the rmni comnmni- 

 cantes are of a compound nature, containing 

 fibres which are sent to the sympathetic from 

 the cerebro-spinal nerves, and also others 

 which are sent to the latter by the sympa- 

 thetic, and which belong to the fine variety of 

 tubular fibres already described as probably 

 arising in part from the ganglionic corpuscles. 



* Selbstandigheit cles Sympathischen Nervensys- 

 tems vou Bidder und Volkmann, p. 29. 

 t Ibid. J Ibid. 



On examining the connection between the 

 sympathetic and cerebro-spinal nerves in the 

 frog, they find that all the anterior branches 

 of the spinal nerves communicate with the 

 sympathetic. The filament of communication 

 with the first spinal nerve at its entrance into 

 it divides into two portions, one of which 

 proceeds towards the spinal cord, the other 

 towards the periphery : when it consisted of 

 two portions, the one was directed towards 

 the centre, the other ran peripherically. Con- 

 nected with the second spinal nerve they 

 found several communicating filaments, the 

 smaller portion of the fibres of which ran 

 towards the centre, while the larger portion 

 was directed towards the periphery. The 

 fibres connected with the third nerve also 

 ran in both directions, the chief portion, 

 however, towards the centre. The fourth 

 communicating branch sent its fibres both 

 towards the centre, and also towards the 

 periphery, the portion running centrally, 

 however, being much more considerable than 

 that running towards the periphery. So 

 also in regard to the fifth ; the portion, how- 

 ever, directed towards the centre did not 

 exceed that passing peripherically so much as 

 in the former. Sometimes they found that 

 the central and peripherical portions were 

 about equal. The sixth communicating branch 

 sent about an equal portion of its fibres in 

 either direction. In regard to the seventh, 

 they found that by far the greater portion was 

 directed peripherically, while only a very 

 small bundle took the direction of the centre. 

 Between the eighth nerve and the sympa- 

 thetic there are frequently two communicating 

 filaments : their fibres are directed almost ex- 

 clusively towards the periphery, only a very 

 small portion being directed towards the 

 centre ; and sometimes even this is wanting. 

 Between the ninth nerve and sympathetic there 

 are commonly two, often also three, filaments 

 of communication with the sympathetic ; and 

 in one case they found as many as six : the 

 course of the fibres here is similar to what 

 it is in the eighth ; perhaps, however, the 

 portion sent inwards towards the centre is 

 even smaller, and not unfrequently fails alto- 

 gether. The communication with the tenth 

 nerve they found was not constant : some- 

 times three communicating filaments were 

 observed ; at others no communication ap- 

 peared to exist. When present, they always 

 ran almost exclusively in the direction of the 

 periphery. Thus, then, of the rami communi- 

 cantes in the frog there appear to be none 

 which consist of fibres entirely derived from 

 the spinal cord, while, on the other hand, some 

 of these consist almost exclusively of fibres 

 which run towards the periphery, and which 

 therefore must be regarded as exclusively 

 consisting of fibres which are sent by the 

 sympathetic to the spinal nerves. The five up- 

 per spinal nerves give to the sympathetic in 

 the frog more fibres than they receive from it, 

 while, on the contrary, the five lower receive 

 from the sympathetic more fibres than they 

 send to it. As regards the communicating 



