374 



GANGLION. 



Notwithstanding these and other high au- 

 thorities, the researches of many recent writers, 

 which have thrown so much new and valuable 

 light on the mutual relations of the component 

 parts of the nervous system, leave little room 

 for doubting the identity of these two sub- 

 stances. The analogy of the whole nervous 

 system tends to prove that this peculiar matter 

 is nothing else than the grey substance ; in the 

 Gasserian ganglion, indeed, the resemblance is 

 so striking that no doubt of their identity can 

 be entertained. This view of the subject was 

 taken by \Vins!ow, Johnstone, and others ; 

 and lately the existence of grey matter has 

 been admitted by Dr. l ; letcher, an assumption, 

 indeed, which is the basis of his hypothesis, 

 that the ganglionic syslem of nerves is the im- 

 mediate seat of irritability.* 

 . II. Fibres. This is a most important branch 

 of the present inquiry, because a knowledge 

 of the connexions of these bodies with the other 

 parts of the nervous system and with each 

 other, as well as of the internal disposition of 

 their fibres, is indispensable to the investigation 

 of their functions. The subject may be re- 

 solved into two questions, a. What is the 

 arrangement of the fibres in the ganglia '! 

 b. What is the nature of the fibres which are 

 connected with the ganglia ? 



a. The internal disposition of the nervous 

 filaments, owing to the very intimate relations 

 subsisting between them and the grey matter, 

 is difficult to determine; and hence it has 

 happened that great difference of opinion pre- 

 vails on this point. I shall in the first place 

 describe the arrangement in the most simple 

 of these organs, and for that purpose shall 

 select that of the portio major of the fifth pair. 

 On insjiection it is seen that the large coarse 

 fibrils of the nerve on approaching the ganglion 

 begin to spread out from each other, and although 

 in its interior they are, as we have already 

 observed, encrusted by the grey matter, yet, 

 on scraping this away, the fibres may be seen 

 still passing on uninterruptedly, but becoming 

 more and more separated from each other. 

 It is this disposition which Scarpa has aptly 

 enough compared to a rope the two ends of 

 which remain twisted, whilst in the middle 

 the component threads are unfolded and pulled 

 asunder. A similar, but less distinct arrange- 

 ment exists in the spinal ganglia. 



Although the continuity of the fibres through 

 the ganglion is easily demonstrated, yet it 

 would be wrong to conclude that this passage 

 is all that happens ; for in the first place the 

 three branches of the trigeminal nerve which 

 emerge from, are decidedly larger than the 

 trunk of the same nerve which passes into 

 the ganglion. Their physical qualities are also 

 altered, especially as relates to their colour, 

 which, instead of having the whitish aspect 

 common to the proper fibres of the cerebro- 

 spinal axis, is for some distance of the reddish 

 hue proper to the ganglionic syslem ; and 

 again it would be in opposition to all our 

 notions of the properties of the grey matter 



* Rudiments of 1'hvsiol. st. ii, a. p. 87. 



to imagine that the fibres do not maintain 

 intimate connexions with that substance, by 

 which means its influence, whatever it may be, 

 is communicated to those threads. 



In the sympathetic ganglions the internal 

 formation is much more intricate ; and it is 

 especially in reference to these bodies that so 

 much diversity of opinion prevails among 

 anatomists. The researches of Monro,* Scarpa,f 

 and Lobstein,J as well as ocular inspection, 

 prove that some fibres undoubtedly pass without 

 interruption through the ganglion. 



On making a section of the first cervical 

 ganglion, previously hardened by alcohol, 

 tibtes will be perceived, which, although se- 

 parated from each other by irregular interstices 

 filled with grey matter, are still continued 

 uninterruptedly from one to the other ex- 

 tremilv. There are, however, besides these, 

 other fibres, which are so complex that it is 

 almost impossible to demonstrate their exact 

 disposition. 1 believe, however, that, inde- 

 pendently of those fibrils which run through 

 the ganglion, there are some which terminate 

 in, and others which arise from the grey matter 

 in its interior. 



Fig. 171. 



Superior cervical ganglion of the great inteecottal 

 nerve of the right side. 



a, Trunk of the great intercostal nerve a little 

 below the foramen caroticum. 6, Trunk of the 

 nerve below the superior cervical ganglion. 

 c, c, c, c. The branches which from Ihe three 

 superior cervico-spinal nerves run to join the su- 

 perior cervical ganglion of the great intercostal 

 nerve, d, d, d, Nerves issuing from the superior 

 cervical ganglion. e t Nervous hbriform stratum of 

 the ganglion. /, Reticulated plexus produced by 

 the mingling of the nervous fibres. g t Reticulated 

 or plexiform nervous filaments. h, Nervous 

 filaments variously mingled with others connected 

 with the neighbouring cerebral and spinal nerves. 

 i, The nervous filaments of which the trunk of 

 the intercostal nerve below the superior cervical 

 ganglion is composed. 



* Obs. on Nerv. Sys. p. 54. 



t I., c. p. 14, Tab. 1. fig. 1,2,3, 4. 



} L. c. Tub. tcrtia. 



