Part 22

This extensibility of the fibrous system is subjected to an uniform law, which is unknown to the extensibility of most of the other systems; it can only take place in a slow, gradual and insensible manner. Thus when it is too quickly put into action, two different phenomena take place, which equally suppose the impossibility of its extending suddenly, as for example, a muscle, the skin, the cellular texture, &c. do. 1st. If the fibrous organ makes a resistance greater than the effort which it experiences, then it does not yield, and different accidents result from it. We have many examples of this, in the inflammatory swellings that appear under the aponeuroses of the limbs, under those of the cranium, within the fibrous sheaths of the tendons, &c. Then these fibrous organs not being able to stretch with the same rapidity as the subjacent parts which swell, compress painfully these swollen parts, and sometimes even expose them to gangrene; this is what takes place in those strangulations so frequent in surgical practice, and which require different operations to relieve them. 2d. If the fibrous organ is inferior in its resistance to the sudden effort which it experiences, it breaks instead of yielding; hence the rupture of the tendons, the tearing of the fibrous capsules and of the ligaments in luxations, that of the aponeuroses in certain very rare cases reported by different authors, &c. &c. We easily understand that the great resistance with which the fibrous texture is endowed, is principally owing to the impossibility of yielding suddenly to the impulse that is given to it.

In the slow and gradual extension of the fibrous organs, we observe that often instead of becoming thinner and enlarging at the expense of their thickness, they increase, on the contrary, in this dimension. The albuginea of a scirrhous testicle, the sclerotica of a dropsical or cancerous eye, the periosteum of a ricketty bone, &c. show us this phenomenon, the reverse of which is sometimes observed, as in the distensions of the abdominal aponeuroses produced by pregnancy, by ascites, and also in hydrocephalus, &c.

The contractility of texture is accommodated in the fibrous system, to the degree of its extensibility; as it cannot suddenly be distended, it cannot suddenly contract when it ceases to be distended. This fact is remarkable in the division of a tendon, of a portion of aponeurosis, of a ligament laid bare in a living animal, in an incision of the dura-mater, to discharge blood effused under it, &c. In all these cases, the edges of the division undergo a separation hardly perceptible; thus in the rupture of the tendons, the separation being produced, not by the contraction of the divided extremities, but only by the motions of the limb, the contact is effected by the position in which in the natural state this tendon is not drawn: whilst in a divided muscle, not only this position is necessary, but that in which there is the greatest possible relaxation, and yet oftentimes contact is not effected. If whilst a muscle is stretched, we cut its tendon in a living animal, the end attached to the fleshy fibres separates a little from the other by the retraction of these fibres; but that which is attached to the bone remains immoveable, so that there is then but one cause of separation to this, whereas there are two in a divided fleshy part. If we cut a tendon when the muscle is relaxed, its ends remain in place.

The contractility of texture is evident, however, at the end of some time, in the fibrous system, especially when the organ has been first stretched; for, when it is divided in its natural state, it is always hardly any thing. The sclerotica after the puncture of the eye, or after the amputation of the anterior half of this organ, and the evacuation of its humours, the tunica albuginea, the peculiar coat of the spleen and that of the kidney, after the resolution of a tumour that had stretched their respective organs, the fibrous capsules after the discharge of the fluid of articular dropsies, the abdominal aponeuroses after the first and even the second accouchement, the periosteum after the resolution of exostoses, &c. gradually contract and resume their original forms.

III. _Vital Properties._

There is never in the fibrous system animal contractility, nor sensible organic contractility. Organic sensibility and insensible organic contractility are found there as in all the other organs.

The animal sensibility exists in it in the natural state; but it appears in a peculiar way, of which no system in the economy, I believe, offers an example and which no one has precisely pointed out. The ordinary agents that put it in action, such as the different stimulants, mechanical, chemical, &c. cannot develop it here, unless the organ is in an inflammatory state. The tendons, the aponeuroses, the fibrous membranes, the ligaments, &c. laid bare in operations, in experiments upon living animals and irritated in various ways do not occasion any pain. What has been written on the sensibility of the periosteum, the dura-mater, &c. taken in this sense is evidently contrary to observation. But if the fibrous organs are exposed to a sudden and violent extension, then the animal sensibility is evident in it to the greatest degree; this fact is particularly remarkable in the ligaments, the fibrous capsules, the aponeuroses, &c.

Lay bare an articulation in a dog, that of the leg, for example; dissect carefully the organs that surround it; remove the nerves especially, so as to leave nothing but the ligaments; irritate these with a chemical or mechanical agent; the animal remains unmoved and gives no sign of pain. Then stretch these ligaments, by twisting the articulation, the animal in an instant throws himself down, is convulsed, cries out, &c. Finally cut these ligaments so as to leave only the synovial membrane which exists here without the fibrous capsule, and twist these two bones in an opposite direction; the twisting ceases to be painful. The aponeuroses, the tendons even laid bare and drawn in an opposite direction, produce the same phenomenon. I have frequently repeated these experiments which prove incontestably what I have advanced, viz. that the animal sensibility of the fibrous system, incapable of being brought into action by the ordinary means, is very evident in the distensions of which they are the seat. Observe that this manner of being excited is analogous to the functions that it performs. Separated in fact by its deep position from every external excitement which can act upon it chemically or mechanically, it has no need, like the cutaneous system for example, of a sensibility which would transmit the impression of it; on the contrary, the most of these organs, as the ligaments, the fibrous capsules, the tendons, &c. being very subject to being distended, stretched and twisted in the violent motions of the limbs, it was necessary that they should communicate to the brain this kind of irritation, the excess of which might without this become injurious to the articulations or the limbs. Observe how nature accommodates the animal sensibility of each organ to the different excitements it may experience, to those especially which would become dangerous if the mind was not informed of them; for this vital power is the essential agent by which the animal watches over its preservation.

It is to this sort of sensibility of the fibrous system that must be principally attributed, 1st, the acute pains that attend the production of luxations; 2d, those more severe ones which patients experience in the extensions necessary to reduce them, especially when, as in those of long standing, we are obliged to employ considerable force; 3d, the intolerable suffering of the punishment that consisted in drawing a criminal with four horses; 4th, the painful sensation which arises from twisting, which is occasioned by a stretching of the spinal column and consequently of its ligaments, by turning the head too quickly, &c.; 5th, the acute pain that those experience immediately before the accident who break a tendon, a pain which ceases in part when the rupture takes place; 6th, that less sensible pain which we feel when any tendon, the tendo Achillis for example, is from a bad position too much stretched; 7th, the great increase of pain that is experienced, when a swelling exists under an aponeurosis, which being unable to yield, is very powerfully raised; 8th, the painful sensation we feel in the ham when we wish to force the extension of the leg, by which we stretch the two oblique ligaments destined to confine this extension, &c. &c.

It is without doubt to the insensibility of the fibrous organs to one kind of excitement, and their sensibility to another, that must be referred the contradictory results of the experiments of Haller on the one part, and those of his antagonists on the other, upon the dura-mater.

_Character of the Vital Properties._

The vital activity is much greater in the fibrous, than in the osseous and cartilaginous systems. This is proved very evidently, 1st, by the degree of animal sensibility which we have just observed in it, and which is foreign to the other two systems; 2d, by the much greater disposition of this system to become the seat of pains more or less frequent, and especially of inflammation, &c.; 3d, by the much more acute character that this affection has in it, as we see in acute rheumatism, which principally affects the fibrous parts of the great articulations of the axilla, the hip, the knee, the elbow, &c. the aponeurotic part of muscles, &c.; 4th, moreover, by the great mobility of rheumatic pains, which go with astonishing quickness from one place to another, which consequently suppose a great quickness in the alteration of the vital forces of the different parts of this system; 5th, by the greater rapidity of its cicatrization; thus by laying bare fractures made for the purpose in animals, I have constantly observed that the fleshy granulations coming from the periosteum and the medullary organ, are all formed, whilst those furnished by the bone itself have hardly commenced. I would observe in regard to this cicatrization, that the parts of the fibrous system in which the greatest number of blood vessels enter, as the periosteum, the fibrous membranes, the capsules, &c. are the most capable of this phenomenon, which takes place with much more difficulty in those where little or scarcely any blood goes, as in the tendons, the ends of which are very slow in uniting; 6th, we may finally be convinced of the difference of vitality of the fibrous system and that of the preceding ones, by the progress of an exostosis compared with that of periostosis, or a swelling of the dura-mater, &c. Yet there is still in respect to the vitality a remarkable slowness in this system. We see it especially in certain affections of the limbs, in which gangrene takes place, and makes, like the inflammation that precedes it, rapid progress in the cellular texture, the muscles, &c. whilst that, as I have said, the tendons that have been laid bare do not alter until some time after, and are remarkable for their whiteness in the midst of the general blackness or lividity.

The fibrous system presents a remarkable phenomenon; it is that it hardly ever contributes to the formation of pus. I do not know that after inflammations of this system, purulent collections have been ever observed. Rheumatism, which is ranked with the phlegmasiæ, is never accompanied by these collections; some gelatinous extravasations only have been found around the tendons. That which was formerly taken for a suppuration of the dura-mater in wounds of the head, is very evidently a purulent oozing from the arachnoides, analogous to that of all the other serous membranes. Why does this system refuse, or produce pus with so much difficulty, or why is it not as much disposed to do it as most of the other systems? I know not. Nor do I know that in the midst of the cartilages collections of this fluid have been found. The inflammations of the cartilaginous system are remarkable, because they rarely or never terminate by suppuration.

_Sympathies._

All the kinds of sympathies are observed in the fibrous system. Among the animal sympathies, the following are some of sensibility. 1st. In certain periostoses which occupy but a small surface, the whole of the periosteum of the bone that remains sound, becomes painful. 2d. After a puncture, or bruise of the periosteum, the whole of the limb often swells and becomes painful. 3d. In the affections of the dura-mater, the eye is frequently affected, and cannot bear the light, a phenomenon which may also depend on the communication of the cellular texture, but which is certainly sometimes sympathetic. 4th. When we make extension to reduce a luxation, and the articular ligaments consequently suffer much, the patient often complains of pain in a very distant part of the limb, &c.

Contractility is also brought into action in the animal sympathies of the fibrous system. 1st. The puncture of the centre of the diaphragm causes, it is said, in the facial muscles, a contraction which produces a sardonic smile. 2d. The injury of the aponeuroses, the stretching of the ligaments in the luxations of the foot and the tearing of the tendons, are frequently accompanied by convulsive motions of the jaws and even well marked tetanus. 3d. A splinter fixed in the dura-mater produces contractions in the different muscles of the economy. 4th. In injuries of the albuginea and the external aponeuroses, we often observe similar phenomena.

In the organic sympathies of the fibrous system, it is sometimes the insensible organic contractility that is brought into action, and sometimes the sensible organic contractility; the following are examples of the first. 1st. The dura-mater being inflamed, the inflammation which always supposes an increase of the tonic forces or of the insensible organic contractility, is often discoverable in the pericranium and vice versa. 2d. The irritation of a considerable extent of the periosteum often makes the medullary organ inflame and suppurate. 3d. The articular ligaments being stretched by twisting, all the neighbouring parts, and frequently the whole limb, swell and become a centre of irritation in which all the vital forces of life, insensible contractility in particular, are found much more raised than usual, &c.

At other times it is the sensible organic contractility which is brought into action. 1st. We often observe in the operation for cataract by depression, that the wound of the sclerotica occasions sympathetic vomitings, risings of the stomach, intestines, &c. 2d. A violent pain in any part, in the fibrous system in particular, increases very much the sensible organic contractility of the heart and thus produces from sympathy an acceleration in the motion which it gives to the blood. 3d. I have seen a man in whom Desault reduced a luxation, and who, from the great pain which the stretching of the ligaments gave him, was unable to retain his fœces, so great was the contraction of the rectum.

We see that in these sympathies, it is sometimes the fibrous system which exerts its influence upon the others, and sometimes they exert their action upon it. It is principally when it is drawn, when the peculiar kind of animal sensibility which it enjoys is put into action that it occasions in the whole economy a remarkable sympathetic derangement. I presume the ancients considered as nerves all the white parts, the ligaments, the tendons, &c. on account of the very serious accidents they had observed from their stretching in sprains, in complicated luxations of the knee, the elbow, the ankle, luxations which can never be produced without a violent stretching of many ligaments, of aponeurotic and tendinous parts, &c. A stroke of a sabre which divides the ligaments of the tarsus, a body which bruises them, produce consequences much less serious, than a false step that twists them. This leads us to an important general consideration, the truth of which is proved by the examination of the other systems; viz. that it is the predominant vital property in a system, which is especially brought into action by sympathies. As the animal sensibility, capable of responding to the agents of distension, is here the most strongly marked, it is this that performs the principal part in the fibrous sympathies.

ARTICLE FOURTH.

DEVELOPMENT OF THE FIBROUS SYSTEM.

I. _State of the Fibrous System in the first age._

In the midst of the mucous state of the embryo, we cannot distinguish the fibrous organs. All is confounded; it is not until many other organs are formed, that we discover any traces of them. Those in the form of membranes appear at first like transparent nets; those arranged in fasciæ seem to be a homogeneous body. In general the fibres are not distinct in the first age; the aponeuroses, the fibrous membranes, the tendons, &c. do not exhibit any trace of them; all then seems to be uniform in the texture of the fibrous organs. In the fœtus of seven months, we begin to distinguish the white fibres. Few at first, and distant from each other, they gradually approximate after birth, are arranged in a parallel manner, or cross in different directions, according to the organ which they finally possess themselves of entirely at a certain age. It is especially on the phrenic centre of the diaphragm, the dura-mater, the aponeurosis of the thigh, that we easily make these observations.

As the fibres are developed in the fibrous organs, they have more resistance and hardness. In the fœtus and in the first years, they are extremely soft and easily yield. Their whiteness has a tinge wholly different from that of a more advanced age; they are of a pearly white. It is only gradually that they arrive at that degree of force that especially characterizes them.

It is to this softness, this want of resistance of the fibrous system in the first years, that the following phenomena must be attributed. 1st. The articulations yield at this age to motions which the stiffness of the ligaments afterwards renders impossible; all extensions can then be carried beyond their natural degree. We know that it is at this period that tumblers begin to practice; they would never be able to execute those extraordinary motions, which astonish us, if habit did not preserve in them from infancy the power of these motions. 2d. Luxations are in general rare in the first age, because the fibrous capsules yield and do not break. 3d. Sprains have then less serious consequences. 4th. The inflammatory swellings under the aponeuroses are rarely susceptible of those strangulations oftentimes so severe at the adult age. 5th. This softness of the fibrous system accommodates itself also in the tendons, the ligaments, the aponeuroses, &c. on the one hand to the multiplicity and frequency, and on the other to the want of power of the motions of the infant.

I would remark, that although the fibrous system has in the first age a softness of texture nearly uniform in all the parts that belong to the same order, yet it is more or less developed according to the regions in which it is found. In general, when it belongs to the organs that are early developed, as to the brain by the dura-mater, to the eyes by the sclerotica, &c. it has in proportion more size and thickness; but it is only in its dimensions, and not in its intimate organization, that these differences then exist.

It is probable that this mode of organization of the fibrous system has an influence, at the period of which we are treating, upon its degree of vitality and consequently upon its diseases. We know that rheumatism, which appears very probably to affect this system, is rarely the attendant of children of the first age; that in a hundred patients affected with it, there are ninety at least above the age of fifteen or sixteen years.

Subjected to ebullition, the fibrous system of the fœtus and the infant easily melts, but does not take that yellow colour, which it constantly has, when boiled in the adult age; we know that the jellies made from young animals are much whiter than those from older ones.

II. _State of the Fibrous System in the after ages._

As we advance in age the fibrous system becomes stronger and more compact; it remains stationary in the adult age, though the alternate absorption and exhalation of nutritive substances constantly continue. These two functions can scarcely be seen in the ordinary state; but the first is very apparent when from a contusion or any internal cause, the periosteum, the fibrous capsules, the ligaments, &c. swell. The second in its turn predominates, when the swelling subsides and resolution takes place.

In old persons, the fibrous system becomes more and more compact and contracted; it yields more slowly to maceration and putrefaction. The teeth of animals that feed upon it, tear it with more difficulty; the gastric juices act upon it less easily. Spallanzani has observed, that the tendons and aponeuroses of old animals were much more indigestible than those of young ones. With age, the force of the fibrous texture increases; but its softness diminishes; hence the difficulty of the motions, from its stiffness. The ligaments and the fibrous capsules do not allow the articular surfaces to separate easily from each other; the tendons bend with difficulty; when we pass externally on places where they are directly under the integuments, we perceive that they are hard, not supple, &c. It requires a long time to soften them by ebullition. The whole fibrous system becomes yellow. We should say that it approached then that state in which it is compact, semi-transparent and has the horny hardening to which desiccation reduces it; so that if we could suppose this system going through quicker than the others the different periods of its decrease, all the motions would cease from the rigidity of the ligaments, tendons and aponeuroses, though the energy of contraction might still subsist in the muscles.

III. _Preternatural Development of the Fibrous System._

We have seen that different productions belonging, by their nature, to the osseous or cartilaginous systems, are sometimes preternaturally developed in certain parts. Morbid anatomy also shows us productions, in which the fibrous appearance is very evident. I have many times made this observation in tumours of the womb, the fallopian tubes, &c. Instead of the lardy matter which is so common in these organic affections, we see one or several masses of fibres, very distinct, yellow, &c. I cannot however say that these excrescences belong essentially, by the substances that compose them, to the fibrous system, not having made upon them, experiments similar to those which I have made upon the organs of this system.

ARTICLE FIFTH.

OF THE FIBROUS MEMBRANES IN GENERAL.

After having considered the fibrous system in a general manner, as it relates to its organization, its life, its properties and its nutrition, I shall now examine it more particularly in the great divisions it offers, and which we have pointed out above. I begin with the fibrous membranes.

I. _Forms of the Fibrous Membranes._

These membranes which comprehend, as has been said, the periosteum, the dura-mater, the sclerotica, the albuginea, the peculiar membrane of the spleen, the kidneys, the corpus cavernosum, &c. are almost all destined to form external coverings, kind of sacs in which are contained the organs they invest.