General Anatomy, Applied to Physiology and Medicine, Vol. 1 (of 3)

by Xavier Bichat

The form of the ganglions is extremely irregular. In general they are round; but sometimes they are long, as the superior cervical; sometimes the ganglion is a species of triangular body, with obtuse and round ends, as the ophthalmic; sometimes the form is semilunar, like that which has this name, &c. Generally these forms are very variable, as I have said; the most uniform is that of the superior cervical.

Embedded in a quantity of cellular texture, all the ganglions are separated by it from the neighbouring organs. Almost all of them are so disposed, that they experience but little motion from these organs, and cannot receive it from any of the vessels that enter them. Those situated along the vertebral column especially, present this phenomenon, very different from that which takes place at the brain, whose functions are essentially connected with the constant agitation that the blood imparts to it, and very different from that which we observe in the plexuses of nerves coming from these same ganglions.

II. Organization.

The ganglions have generally in the adult a reddish colour very different from that of the nerves; sometimes they are greyish. When opened, they present a soft, spongy texture, resembling considerably at first view that of the pretended lymphatic glands.

This texture has nothing in common with the cerebral substance, nor with that which occupies the canal of the nervous coat. These two last should rather be ranked in the class of fluids, as I have said; their substance is a pulp, a real jelly. Thus they have not any of the properties of solids. They do not harden like horn; the kind of hardening, the result of the contact of alkohol, of the acids, and of caloric, is wholly different from the horny hardening. It is analogous to the hardening of the white of an egg. On the contrary, the texture of the ganglions hardens like horn in an evident manner, a phenomenon which is characteristic of all the solids, except the epidermis, the nails, and the hair, which make a separate class. Treated by the acids, the ganglions, after wrinkling, hardening like horn and hardening gradually, soften and become fluid.

Boiling produces a phenomenon nearly analogous; 1st. horny hardening and hardening at the instant the water boils; 2d. continuance of this state for half an hour; 3d. softening gradually brought on; when this last is complete, the effect of the boiling is finished. In this state, the ganglions are all different from the nerves submitted to the same experiment. I have observed also in veal, that they have a very different taste from that of the nerves, a method of research which should not be neglected in attempting to ascertain the difference of the nature of the organs. In fact, as we do not yet know the difference of the principles which enter into the composition of each, we should be satisfied with the difference of the qualities.

The alkalies act a little upon the ganglions, which they tend to dissolve, and which they do partly dissolve, if they are very caustic. But this solution is infinitely less prompt and less easy than that of the cerebral pulp by the same re-agents. The ganglions resist putrefaction as much and even more than the nerves; this forms also a very remarkable difference between them and the cerebral substance. In general, we cannot establish any kind of analogy between them.

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.