Part 21

The texture of the ganglions appears in nowise fibrous; there is absolutely no linear, filamentous appearance, &c. upon simple inspection. Homogeneous, if we may so say, in its nature, it presents every where an uniform aspect when cut in slices. However the celebrated Scarpa has considered the ganglions as resulting from a kind of expansion of the nerves, into an infinite number of extremely delicate fibres, which interlace with each other, and which become very distinct by maceration. I have not repeated all his experiments, which appear to me extremely difficult. I refer then to his work, and to the plates it contains. I would observe only that there is certainly something else in the ganglions, besides a simple division of the nerve into extremely fine threads. In fact, mere inspection is sufficient to establish between them the greatest difference. There is as evident a demarcation between the ganglions and the nerves, as between those of the brain and the brain itself. 1st. Difference of colour, reddish or greyish tinge in some, white in others; 2d. difference of consistence, of external qualities, &c.; 3d. difference of properties. If the nerves coming from the spinal marrow make only an expansion, in their passage, in the ganglions, by delicate filaments, there would then be only a difference of form and not of nature; the properties would be the same. Why then are they so different as I shall prove hereafter? Why, as a nerve goes from a ganglion, does it not communicate more voluntary motions? 4th. Why has not nature placed ganglions in the nerves of the extremities as in those of the other parts? If there is only a division of the nerve into finer filaments, in the ganglion, why is there not a proportion between the filaments that enter on one side, and those that go out at the opposite? In fact, those that enter into the superior cervical above, if they only expanded their filaments in this ganglion, and united afterwards to form those that go off below, would be equal in respect to size to those that go from it; all the ganglions would exhibit this constant relation between the nerves of one side and those of the opposite; now, it is sufficient to examine them to be convinced that an inverse arrangement exists. 6th. The ganglions ought always to be in proportion to the size of the nerves which form them by spreading their fibres. Why then are the intercostal ganglions so small, and the trunks that unite them, or rather that give origin to them and which go from them afterwards as we see in the usual manner, so large? Why on the contrary, is the superior cervical ganglion so large, and its branches so small? 7th. How can be explained the frequent interruptions between the ganglions in man, which are constant in many animals, if there is a continuity between the nervous filaments that enter the ganglions above, and those that go from them below? 8th. How does it happen that the ganglions and their nerves do not follow an exact proportion as to development with the cerebral nerves, if these form them by expanding? 9th. Why has not pain the same character in each species of nerves?

I have no opinion as to the nature or the functions of the ganglions, because I have no fact to support me; but there is certainly something more in their texture, than a mere expansion of nervous filaments. Scarpa admits a peculiar matter which separates these filaments; but this substance ought to predominate considerably, as the ganglion surpasses in size the nerves which are thought to give origin to it. Now I have never seen this substance; I do not know what it is; all is solid when the ganglion is cut. I think then by admitting, even to a certain extent, the internal arrangement that this author has observed in the ganglions, we cannot describe these organs in the point of view in which he has presented them.

We know but little of the alterations that diseases produce in the texture of the ganglions. I have already many times examined in diseases of the heart, of the liver, of the stomach, the intestines, the ganglions that send nerves to these viscera; they have never appeared to me to have undergone any change. In cancers of the stomach in the very last stage, in which all the cellular texture is engorged, and in which all the lymphatic glands are considerably swelled, I have always found the semi-lunar ganglion untouched, except however in one case where it was enlarged and its density a little increased. At another time I found this same ganglion of the size of a small nut, with a cartilaginous substance in its centre, resembling the stone of it, in the body of a man brought to the Hôtel Dieu on account of periodical mania. Some authors have thought, and I suspect the same thing also, that the hysteric paroxysms, which begin by a contraction at the epigastric region, and in which the patient feels a ball mount up even to the throat, arise from some affections of the semi-lunar ganglions, from the solar plexus and the communications which go from ganglion to ganglion, even to the neck. However two bodies that I have opened lately, exhibited no alteration, though during life the subjects had been frequently attacked with these paroxysms; but they may arise evidently from the ganglions and the epigastric plexuses, without their being altered in their structure, as a number of cerebral affections leave after them no trace in the brain. This point deserves particular examination.

It does not appear that the texture of the ganglions is surrounded by a peculiar membrane. The cellular texture is only condensed in their neighbourhood; it then becomes very consistent, and much contracted around them. It there has the nature of the sub-mucous, the sub-arterial textures, &c.; it never contains fat. There is then truly around the ganglions, as around the arteries, under the mucous surfaces, &c. the two kinds of cellular texture of which we have spoken in treating of the organization of this texture, and which differ so essentially from each other in their nature, and even in their properties. It is the second kind, which is analogous to the sub-arterial texture, &c. which forms the peculiar membrane admitted by some authors.

By examining attentively the interior of the ganglions, we see that there is but very little cellular texture there. I have found this texture constantly destitute of fat; thus the alkalies do not form a saponaceous deposit upon them, as upon the cerebral nerves when plunged in their solution. I have examined many ganglions in this way, on account of the opinion of Scarpa, who believes that these organs are penetrated with this fluid, at least in fat people.

The ganglions receive many blood vessels. These penetrate them from all sides, run first in a kind of cellular covering that surrounds them, then entering their texture, ramify and are lost there in numerous anastomoses, and in continuation with the exhalants that carry nutritive matter. Fine injections show a great quantity of vessels in these little organs. Nutrition supposes exhalants and absorbents there.

III. _Properties._

It is difficult to analyze the properties of texture in the ganglions. As to vital properties, they cannot grow, live and be nourished without organic sensibility, and without insensible contractility of the same kind. Animal and sensible organic contractility do not exist there evidently. As to animal sensibility I have observed the following circumstance. As in opening the abdomen of an animal, of a dog, for example, he lives very well for some time, and remains even calm after the first moments of suffering; I have waited for this calm that succeeds the agitation arising from the incision of the abdominal parietes, then laid the semi-lunar ganglion bare, and irritated it powerfully; the animal is not agitated, whilst when I excite a cerebral lumbar nerve, for comparison, he cries out, raises himself up and struggles. In general it appears that the sensibility of the ganglions is infinitely less evident than that of many other organs. Certainly the skin, the mucous system, the medullary, the nervous of animal life, &c. surpass it in this respect.

Our ignorance as to the diseases that have their seat in the ganglions, the distance of those organs from external excitement, prevent our having any data as to their sympathies. I think it very probable, however, that these sympathies take a real part in hysteria, in certain kinds of epilepsy, the paroxysms of which begin, like those of hysteria, by a painful sensation at the epigastric region, in that multitude of affections called nervous, and which the vulgar confound under the name of vapours. One of the most important objects of research in the neuroses, is to determine those that have their particular seat in the nervous cerebral system and those which affect more particularly the system of the ganglions. Place on one side, palsy, hemiplegia, convulsions of infants, tetanus, catalepsy, apoplexy, the greatest part of epilepsies, all the numerous accidents that arise from engorgements, from compressions of the brain from wounds of the head, nervous affections of the sight, hearing, taste, smell, &c. and all the diseases the source of which is evidently in the head; on the other place hysteria, hypochondriasis, melancholia and all that numerous class of affections in which the abdomen and the thorax, the first especially, seem to be the spot in which the evil is seated; you will see that there is an essential difference and that the symptoms have entirely a different character. I do not say that the last kind of nervous diseases affect exclusively the ganglions; for too much obscurity hangs over these affections to pronounce any thing positive as to their seat, or their nature. Undoubtedly even the secretory, circulating, pulmonary organs, &c. can be then particularly affected in their peculiar texture and independently of the nerves they receive; but certainly it is an interesting subject of research, and there is too great a difference in the phenomena of the two orders of affections, not to present differences in their primitive seat. It is difficult to conceive that the system of the ganglions has not a great part in the last order.

That which induces me to think that the difference of the phenomena that the general order of neuroses presents us, arises particularly from the difference of the cerebral nerves and of those of the ganglions, is that their phenomena in a state of health are very different. Hallé has observed very well that the pains that are experienced in the parts in which the nerves coming from the ganglions are distributed, have a peculiar character, and that they do not resemble those that are felt in the parts where the cerebral nerves are sent. Thus the painful sensation that is experienced at the loins in affections of the womb, by vinous injection made into the tunica vaginalis, &c. a sensation that appears to me to arise from the sympathetic influence exercised by the organ affected upon the lumbar ganglions, the pains of the intestines, the burnings at the epigastric region, &c. &c. do not resemble pains of the external parts; they are deep, and go to the heart, as we often say. We know that there are colics essentially nervous, which are certainly independent of every local affection of the serous, mucous, and muscular systems of the intestines. These colics are evidently seated in the nerves of the semi-lunar ganglions, which are spread along the whole course of the abdominal arteries. They are real neuralgias of the nervous system of organic life; now these neuralgias have absolutely nothing in common with the tic douloureux, sciatica, and other neuralgias of the nervous system of animal life. The symptoms, the progress, the duration, &c. every thing is different in these two kinds of affections.

What I have just said upon the injuries of sensation, applies also to those of motion. No kind of comparison can be made between the convulsions of the muscles that receive the nerves of animal life, and the spasmodic and irregular motions which arise in all the muscles that receive nerves from the ganglions. Nothing resembles tetanus in the heart, the intestines, the bladder, &c.

All these considerations establish striking differences between the cerebral nerves and those of the ganglions; differences upon which I can only present approximations, as we have no data as to the functions of the last.

IV. _Development._

The ganglions differ essentially from the brain in the early periods in their development, which is proportionably much less advanced than that of the brain. They are only on a level with all the other organs, whilst this is infinitely superior to them in this respect, as we have seen. By comparing the superior cervical, semilunar ganglions, &c. in the fœtus, and in the adult, it is easy to make this remark. The ganglions receive also less vessels in proportion than the brain. They do not follow the proportion of increase of the organs to which they send nerves. Thus those that furnish the genital organs, which are nearly nothing during the first years of general nutrition, are as large in proportion as those which go to the liver, the stomach, the intestines, which are characterized by an early increase. These nerves follow in this respect the same law as the ganglions, though the most are found upon the arteries, which are more or less developed according to the organs they penetrate.

The nervous system of organic life being less early in its development than that of animal life, should be subject in infancy to fewer affections; and this is what is observed. Convulsions, and most of the neuroses of the second, are, as we have seen, a peculiar appendage upon infancy. On the other hand, the particular order of nervous affections of which we have spoken, and in which it appears that the first takes the principal part, is generally less frequent at this period. All nervous diseases, whose peculiar seat seems to be at the epigastric region, in which there is so great an abundance of nerves coming from the ganglions, appear to be foreign to this age.

Another difference that distinguishes the ganglions from the brain as it respects development, is this, that in the fœtus, they are not, like it, of extreme softness. Their hardness is little inferior to what they afterwards possess in adult age.

In proportion as we advance from infancy, the organic nervous system begins to become predominant. It is towards the thirtieth or fortieth year that it appears at its maximum of action; it diminishes as we approach old age; it decays in part at this epoch. The nerves become greyish; the ganglions are hard, resisting and smaller. The neuroses that appear to belong to them are infinitely more rare. Moreover, the obscurity that rests upon the functions of this system, does not allow me to point out definitely the alterations they experience in the different ages.

V. _Remarks upon the vertebral ganglions._

In all that I have said thus far upon the ganglions, I have not noticed those which correspond with the foramina through which the nerves pass, and which some call simple ganglions. We know that at the instant each nerve goes from each of these foramina, it exhibits an evident enlargement, reddish, pulpy, analogous in its appearance to most of the ganglions. I confess, that I know not how to class these organs. We cannot deny that they have the greatest analogy in structure to the others. They are approximated in another respect, which is this, that the nerves, in going from them, form almost immediately plexuses that we have designated under the names of cervical, brachial, lumbar, and sacral, in the same way as the solar, cardiac, mesenteric plexuses, &c. are formed by the nerves of organic life, at the moment they go from their respective ganglions. However, these last nerves are conductors of very different properties. Irritate in a living animal the superior cervical ganglion, the inferior even, which is more difficult, though it may be come at, the muscles to which they send nerves will remain unmoved; the same phenomenon takes place by exciting the nerves themselves. On the contrary, every irritation of a filament coming from the vertebral ganglions, produces immediately convulsions in the corresponding muscles. The sensibility is entirely different in the two species of nerves. Besides, there is no analogy between the manner in which the nerves go in all directions from the vertebral ganglions, and that in which the other ganglions furnish theirs. In the expectation that further experiments may elucidate the subject, let us content ourselves with pointing out what is the result of accurate observation.

ARTICLE SECOND.

OF THE NERVES OF ORGANIC LIFE.

I. _Origin._

Each ganglion is, as we have seen, a centre from which go in different directions, various branches, the whole of which form a kind of little separate nervous system. The manner of the origin of these branches has but very little relation with that of the branches of the brain and of the spinal marrow. The following are some differences that distinguish it.

1st. The adhesion is much stronger; the nerve breaks any where else rather than at its origin; the opposite of this takes place in the preceding system. 2d. It does not appear that the substance of the ganglion is continued in the nerve to form the medullary substance of it, since the organization of the one and the other is very different. Sometimes, however, the ganglion is continued for a short distance in the form of a cord. This happens especially in the superior cervical, in the lumbar, the semi-lunar, &c. Then the form only is different; but it is easy at the first view to distinguish where the ganglion ends and the nerve begins. 3d. This beginning is made in a sudden manner; it is like a muscle implanted in a tendon. The best manner of seeing this arrangement to advantage is to cut longitudinally the superior cervical ganglion and the cord it sends to the inferior; the change of nature of the one and the other is then very apparent; or, if we consider the ganglion as a division of the numerous filaments of the nervous cords, we distinguish very well the sudden change that these filaments experience in passing from the cord to the nerve. 4th. The dense cellular covering that surrounds the ganglion is continued upon the nervous origin, and gives it an increase of consistence at that place. This must be carefully raised before we come to the nerve. We see then each distinct filament arising from the ganglion. After it has gone from it, sometimes it remains separate; this takes place at the semi-lunar, the lumbar, the opthalmic, whose elongations are of great delicacy. Sometimes many of these filaments unite together and form a cord as between the two cervical, as at the great and small splanchnic nerves, &c.

I have not been able by maceration, ebullition, or the action of the acids to destroy the adhesion of the nerve with the ganglion, as we destroy that of the muscle with the tendon, of this with the bone, &c.

II. _Course, Termination, Plexuses._

The nerves after going from the ganglions, are distributed in many different ways which we shall now examine.

1st. There are always some which go immediately to communicate with the system of animal life. The ophthalmic ganglion sends branches to the motores communes, and to the nasal nerve. The spheno-palatine communicates with the superior maxillary nerve; the superior cervical with all the nerves that surround it, viz. above with the motor externus, within with the great hypoglossal, the par vagum, the glosso-pharyngeal, the spinal, &c.; behind with the first cervical pairs. All the ganglions situated above each other along the vertebral column, send communications through each pair of foramina that correspond with them. The par vagum communicates with the semi-lunar, &c. It is not then any separate ganglion of the nerves of animal life; hence the common expression that designates each ganglion as arising from this or that pair, or being found in its course, is very inaccurate. Thus the opthalmic is by no means in the course of the common motor nerve. The one and the other send each a branch, which unites; or rather there is a branch of communication between the ganglion and the cerebral nerve. In general all these branches of communication with the system of animal life, are short, whitish, and of the same nature, or at least of the same appearance as the nerves of this last. They do not form any plexus in their course, rarely furnish branches, and appear to have no other use than that of establishing anastomoses between the two systems.

2d. Each ganglion sends above and below branches to the two ganglions that are contiguous to it. We have seen that the opthalmic and the spheno-palatine are exceptions to this rule. Sometimes also, as I have said, there are interruptions in other regions. Notwithstanding this, these general communications make us regard the ganglions as being connected every where, and able to receive from each other the different affections of which they can be primitively the separate seat. These branches of communication are straight as in the preceding, sometimes very fine, as between the lumbar and sacral ganglions, at other times larger, as that which is between the two cervical, superior and inferior, in some cases very large, as the great splanchnic, which is a real trunk of communication between the intercostals and the semi-lunar. The nerves that we are now considering, the last especially, have like the preceding, an arrangement exactly analogous to the cerebral nerves; they are formed of whitish cords, which are the result of filaments. The eye discovers no difference between them.

3d. Many filaments coming from ganglions, go to certain cerebral muscles, as to the diaphragm, some of those of the neck, &c.; others go to neighbouring organs only.

4th. The greatest number going from the ganglions in separate filaments, interlace in the form of a plexus with those of the contiguous ganglions, in the neighbourhood of, or upon the great vessels. The most remarkable plexus is the solar, composed by the innumerable branches that come from the semi-lunar; then we see the hypogastric, the cardiac, &c. The greater number of these plexuses are not exclusively formed by the nerves of organic life; those of the animal give some to them also, as the par vagum furnishes an example for the solar and the cardiac, as the sacral nerves afford another for the hypogastric, &c. However the nerves of organic life always predominate in these plexuses. There is only the pulmonary in which the par vagum particularly predominates, whilst the nerves coming from the inferior cervical ganglion are, if we may so say, but accessory.

The primitive plexuses resulting from the interlacing of the organic nerves at their exit from the ganglions, form a mass of irregular nerves, buried in the cellular texture, accommodated to the forms of the neighbouring organs, and wholly different from those of animal life, as of the brachial, the lumbar, &c.

In fact, the filaments at every instant, not only place themselves as in the preceding ones, at the side of each other, at every change of position; but their extremities continue; they interlace with each other, change at every point the direction, form networks, and mix so together, that it is not possible to distinguish any thing except a thousand nerves, that we might say grew up under the cloth with which we wiped the place where the plexus was found.