372 



GANGLION. 



nold ; in the second order arc enurueraled the 

 thirty spinal ganglions and the ganglionic en- 

 largement of the nervus va^us and glosso-pha- 

 ryngeus; in the third division are included the 

 ganglions of the sympathetic nerve. 



The former of these arrangements is objec- 

 tionable, because offices are assigned to the 

 ganglions the existence of which has not been 

 ascertained ; and the latter is so far erroneous 

 that in this classification the ganglion of the 

 tifih pair is separated from the spinal, to which 

 it is undoubtedly similar; whilst the ophthalmic 

 and spheiio-palatine are as incorrectly divided 

 from the system of the sympathetic.* 



In endeavouring to detect that which con- 

 stitutes the essential difference among these 

 numerous bodies, we ought to pay special 

 attention to the character of the nerves which 

 are attached to the ganglions. Taking this as 

 the only rational guide, I should refer them to 

 two classes. 1. Those which are placed on 

 sentient nerves, comprising the Gasserian, the 

 ganglion of the glosso-pharyngeus, and the 

 spinal ganglions The gangliform enlargement 

 of the nervus vagus should be referred to this 

 order, inasmuch as there can be little doubt, 

 although this at present is not proved, that this 

 nerve is compounded, like the spinal nerves, of 

 motor and sentient fibrils, a surmise supported 

 by the distribution of the vagus, and still more 

 by the interesting discovery of my friend 

 Mr. Solly, of the existence of certain motor 

 fibrils in the exact part of the medulla oblon- 

 gata, whence this nerve arises.f 



2. Those which have connected with them 

 both motor and sentient nerves, and are, as I 

 believe, always in relation with contractile and 

 sensitive structures : J those, namely, of the 

 great sympathetic nerve, comprising the cer- 

 vical, the dorsal, lumbar, and sacral, together 

 with the cardiac, the semilunar and coeliac, 

 also the ophthalmic, the spheno-palatine, the 

 otic, submaxillary, and cavernous. 



These classes nearly correspond with the 



* The following is the classification of M'ullcr : 

 1. Ganglia of the posterior roots of the spinal 

 nerves, of the larger portion of the nervus trigc- 

 minus, of the nervus vagus, and ganglion jugularc 

 nervi glosso-pharyngei. 2. Ganglia of the great 

 sympathetic. 3. Ganglia which occur at the points 

 of junction of the cerebro-spinal nerves with the 

 branches of the sympathetic, comprising ganglion 

 petrosum nervi glosso-pharyngei, inturaescentia 

 gangliformis nervi facialis, ganglion spheno-pala- 

 tinum, ciliare, oticum (probably). To which should 

 be added ganglion submaxillare. Handbuch der 

 Physiol. der Meiischco. Erster Hand. p. 588. 



t According to the present opinion, the whole of 

 the fibres belonging to the nervus vagus enter into 

 the ganglion , and Bischoff imagines that this nerve 

 derives iis motor portion from the spinal accessory. 

 The intimate relations between these two nerves 

 require further investigation. 



J It cannot be too often repeated that sensibility, 

 or, to speak more correctly, the capability of being 

 excited by the contact of a physical agent, may 

 exist without being accompanied wiih conscious- 

 ness : the inner surface of the heart, of the blood- 

 vessels, and intestine arc as capable of being ex- 

 riti-d as the skin or the retina ; but the impressions 

 whirh they receive arc not usually perceived by the 

 luind. 



simple and compound ganglions of Scarpa* and 

 Meckel.t 



There are occasionally found ganglia on 

 other nerves ; thus, Mr. Swan \ has noticed one 

 on the posterior spinal nerve, where it is 

 placed under the extensor tendons of the 

 wrist. My friend Mr. Pilcher has also found 

 in two subjects a gangliform enlargement on 

 the internal nasal nerve, where it is lodged on 

 the sethmoidal bone. 



It is necessary to remark that although the 

 ganglia of the first class are placed on certain 

 of those nerves which are commonly regarded 

 as being subordinate simply to sensation, yet 

 the highly important observations of Dr. M. 

 IIall, which have, I conceive, opened an en- 

 tirely new field in physiology, render it doubt- 

 ful that those bodies are essential to the exer- 

 cise of sensation. 



Organization. Although the cerebro-spinal 

 and sympathetic ganglia present some impor- 

 tant peculiarities when contrasted with each 

 other, particularly as regards the proportions 

 of the grey and fibrous substances, still as 

 both classes possess essentially the same struc- 

 ture, they may with propriety be considered in 

 a collective manner. 



Every ganglion contains two totally distinct 

 substances which have a close relation to, and 

 are, I believe, identical with the grey and 

 fibrous matters, constituting the encephalon 

 and other parts of the nervous system. It is 

 true that the appearance of these bodies is in 

 many respects dissimilar to that of the brain ; 

 but at length it is universally admitted that 

 differences in mere physical properties are 

 unimportant, and do not constitute any test as 

 to the essential structure of an organ. In the 

 present instance the diversity may very readily 

 be understood when the difference of situation 

 is considered. The cerebral organ is enclosed 

 in a cavity, the cranium, formed of some of 

 the strongest bones of the skeleton, and hence, 

 being effectually defended from the effects of 

 motion and external pressure, all its parts are 

 soft and delicate; whilst the ganglia, placed 

 ou bones which move on each other, slightly it 

 is true, are exposed to external compression, 

 and consequently a much firmer texture is 

 required. It is for this reason that these 

 bodies are invested in a dense fibrous capsule, 

 which is to them what the cranium is to the 

 encephalon, and which furnishes in addition a 

 number of internal processes surrounding each 

 fibril, and sustaining the spherical masses 

 of grey matter. The difficulty of detecting 

 the intimate texture is by these means greatly 

 increased ; but as it is so similar to that of the 

 cerebrum, it is desirable to examine the con- 

 stituent parts according to the order observed 

 in investigating that organ. 



I. Reddish grey matter. The quantity of 

 this substance, often called the peculiar matter 

 of the ganglions, but which, as I have stated, 



Anat. Annotat. liber primus. De nerv. gang, 

 et plex. p. 9. 



t Man. d'Anat. t. i. p. 231. 



f On the Nerves, pi. xxii. fip. 3. 



$ Lcct. o'n the Ncrv. Sys. 1830'. 



