444 



SYMPATHETIC NERVE. 



tomists, the sympathetic was described as a nerves, reinforced by fibres sent to it from 

 continuation of the fifth and sixth cranial the dift'erent-cerebro spinal nerves along its 



membrane. The number of processes varies between 

 three and twelve ; by speedily branching they may 

 be increased threefold and upwards. The number 

 is regulated by the number of nerves connected 

 with the ganglion ; and hence it is smaller in the 

 main cord than in the solar plexus. The processes 

 have in general the optical and chemical properties 

 ot the axis C3'linder of the uerve-libres. In the 

 solar plexus there are found, however, ganglion 

 cells whose processes are distinguished from one 

 another in a similar manner to those of the ganglion 

 cells in the electric lobes of the torpedo. Besides the 

 multipolar ganglion cells, bipolar cells are also ob- 

 served in the plagiostoinata and mammalia. They 

 differ from those of the spinal ganglia, however, in 

 this, that both processes branch, thus coming to 

 agree essentially with the multipolar cells. The 

 same holds of the unipolar cells which, in the ani- 

 mals mentioned, are sometimes found along witli 

 multipolar, and which in the batrachia and osseous 

 fishes, as well as in the head of the mammalia, 

 almost alone constitute the sympathetic ganglia. 

 In transverse or longitudinal sections of the thoracic 

 or abdominal sympathetic ganglia in the mammal 

 or plagiostome, the simple (generally very broad) 

 processes of such a unipolar cell are seen after a short 

 course to divide into numerous fibres, which pass 

 oft' from one another in different directions. That 

 all the processes take a peripherical course cannot, 

 according to Kemak, be demonstrated, and is, from 

 what follows, improbable. 



He has ascertained, namely, that in the mam- 

 malia the multipolar ganglion-cells of the ganglia 

 in the main cord of the sympathetic in the abdomen 

 and thorax become continuous by means of their 

 processes with the axis cylinder of nerve-fibres with 

 dark borders, of such, too, as pass from the spinal 

 ganglia into the ganglia of the main cord. In man 

 and in the mammal, each ganglion in the main 

 cord is connected, by at least two branches, with 

 spinal nerves. The under branch (ramus com- 

 municans sympatliicus s. revehens) is, according to 

 his observations, gray, contains very fine (the fibres 

 of Bidder and Volkmann) nerve-fibres, and very 

 many ganglion-fibres: it joins a spinal nerve for 

 peripherical distribution after it has at its place of 

 entrance, sometimes close to the spinal ganglion, 

 formed another ganglion consisting of multipolar 

 cells. The upper branch (ramus communicans 

 spinalis, s. adveheus) is white : it contains the fibres 

 which, according to Wiitzer, &c., may be followed 

 to both roots of the spinal nerves. Eemak has as 

 yet succeeded in seeing fibres of this branch enter 

 merely into the anterior root ; the remainder, gene- 

 rally the smaller number, are lost in the spinal 

 ganglion. The sensory fibres destined for the sym- 

 pathetic nerve must, therefore, as it appears, be- 

 come connected with cells of the spinal ganglia 

 before they pass into the main cord of the sympa- 

 thetic. The fibres of this spinal communicating 

 branch either pass directly into the ganglia of the 

 main cord, or they form in part separate white 

 bundles, which apply themselves to the cord, and 

 are lost in the next ganglion behind. Since, now, 

 as transverse sections of the glangia in the main 

 cord show, all entering spinal fibres become con- 

 nected one after another with multipolar glanglion- 

 cells, it follows that if the anterior roots of the 

 spinal nerves contain merely motor fibres, the 

 posterior merely sensory, the multipolar cells in 

 the ganglia of the main cord are found as well in 

 the course of sensory as of motory nerve-fibres. 

 From these cells there pass off in the peripherical 

 direction both broad nerve-fibres with dark borders, 

 and fine fibres (fibres of Bidder and Volkmann), 

 likewise others in which no dark borders can be 

 observed. All these peripherical fibres may be 

 named sympathetic, in opposition to the spinal 

 fibres with which they are connected by means of 



the multipolar ganglion-cells. There are no grounds 

 for the assumption that (human) sympathetic fibres 

 exist which do not stand in connection with spinal 

 fibres, and consequently not in connection with the 

 great central organs of the nervous system. So 

 also in the nerves passing off from the sj'iupathetic 

 ganglia to organs no spinal fibres have as yet been 

 demonstrated in whose course no sympathetic gan- 

 glion-cells are found. 



By the above results, it is merely established 

 that in the sympathetic ganglia the angles of 

 branching, or points where sensory and motor fibres 

 divide, contain ganglion-cells. The ganglia are not, 

 however, thereby established to have the function 

 of central organs, so far as we make them depend- 

 ant on the conflux of sensory and motor fibres, and 

 so long as there is no ground for supposing that 

 among the peripherical fibres passing from a sen- 

 sory or motor sympathetic ganglion-cell, as well 

 sensory as motor fibres are found. Ganglion-cells 

 have been observed by Leydig in the angles of 

 branching of sensory fibres in CarinariaMediterranea. 

 In the angles of branching of motor fibres gan- 

 glion-cells are onlj r known in the great central 

 organs. This of itself gives ground for the ques- 

 tion, whether the sympathetic ganglia have the 

 function of central organs ; that is, whether in 

 them there are distinct sensory and distinct motor 

 cells, or whether each multipolar cell serves as a 

 medium of connection between sensory and motor 

 fibres. On the spinal communicating branches, 

 the question has not hitherto been determined, 

 because they are too long, and a trustworthy 

 microscopic distinction between the two kinds of 

 fibres is wanting. On the other hand, other obser- 

 vations favour the view that the multipolar cells 

 are connected both with motor and sensory fibres. 

 In ganglion-cells whose long axis is the same as 

 the long axis of the ganglion, there are frequently 

 seen two fibres entering at one pole and two pass- 

 ing off from the other. If all four fibres were of 

 the same kind, the cell would then form an anas- 

 tomosis between fibres of the same kind, as has only 

 once hitherto been observed by Leydig, as a variety 

 of the bipolar cells in the Casserian ganglion of 

 Chimsera monstrosa. If, moreover, in a small 

 multipolar ganglion taken from the solar plexus of 

 a mammal (ox), the number and direction of the 

 nerves passing to and from it be compared with the 

 number and the direction of the processes of the 

 cells, as seen on a transverse or longitudinal section 

 of the ganglion, the fullest correspondence is found 

 to exist between them ; that is, in such a multipolar 

 ganglion each ganglion-cell is connected with 

 nerve-fibres of all the nerves which are connected 

 with the ganglion. That in these cases, each of 

 the nerves entering or leaving the ganglion con- 

 tains only sensory or only motor fibres is, however, 

 improbable for this reason, that in other multipolar 

 sympathetic ganglia, for example, the ciliary, 

 otic, and spheno-palatine, we know that the enter- 

 ing nerves contain sensory as well as motor fibres. 



If the sympathetic ganglion-cells serve as con- 

 necting media between sensory and motor fibres, 

 then the impressions made upon sympathetic sen- 

 sory fibres may be transferred by these ganglion- 

 cells to sympathetic motory ; through the medium 

 of the spinal sensory communicating fibres they 

 will also be enabled to act upon the great central 

 organs (brain and spinal cord), and thence through 

 the spinal motory upon the sympathetic ganglion- 

 cells and their motor processes. Besides the sym- 

 pathetic sensory and sympathetic motory fibres, the 

 assumption of a third set of sympathetic fibres, 

 serving immediately for nutrition, is not required 

 by any fact m physiology, since it is possible to ex- 

 plain the dependence of nutrition upon the nerves 

 by the action of the latter upon the contractile 

 walls of the blood-vessels. 





