Chapter X: Part 10

1st. The tendons are found at the origin, insertion or middle of the muscles. They are either simple, in the form of elongated cords, as in the peronæus, the tibialis, and almost all the muscles, or compound, as in the rectus, the flexors, &c.

2d. The ligaments strengthen the osseous or cartilaginous articulations, around which they are found. They have regular fasciæ, as the lateral ligaments of the elbow, the knee, the jaw, &c.; or irregular fasciæ, as those of the pelvis.

III. _Table of the Fibrous System._

We can in the following table present at a single view the classification of the fibrous organs that I have just pointed out.

┌ ┌Fibrous Membranes.
│ │Fibrous Capsules.
│ │ ┌Partial.
│Of a membranous │Fibrous Sheaths. └General.
│ form. │ ┌Partial.
│ │ ┌For covering └General.
FIBROUS │ │Aponeuroses │
ORGANS. │ │ │ ┌With a broad surface.
│ └ └Of Insertion│In an arch.
│ └With separate fibres.
│
│ ┌Tendons ┌Simple.
│In the form │ └Compound.
│ of fasciæ. └Ligaments ┌With regular fasciæ.
└ └With irregular fasciæ.

Though the numerous organs which enter into this classification, belong to very different apparatus, though they seem to be spread here and there in the economy, without holding together at all, and though all appear insulated, yet they are almost all continuous and connected; so that we may consider the fibrous system, like the vascular and cerebral nervous systems, that is to say, as having a common centre, from which all the different organs go that form its divisions.

This common centre of the fibrous system appears to me to be the periosteum, not that I pretend that like the heart or the brain, it sends out radiations upon the organs that go from it, but because anatomical inspection shows us that all the fibrous organs are intimately connected with it, and by its means communicate with each other; the following observations are a proof of this.

1st. Among the fibrous membranes, that of the corpus cavernosum intermixes with the periosteum below the ischium; the dura-mater is continued with it through the foramina at the base of the brain; by uniting itself by the lamina which accompanies the optic nerve to the sclerotica, it joins to it this membrane, and thus serves as an intermediate organ for them. 2d. All the fibrous capsules above and below the articulation intermix with the periosteum. 3d. Wherever fibrous sheaths exist their fibres intermix with those of the periosteum. 4th. All the aponeuroses either of covering or insertion have a similar intermixing. 5th. Wherever the tendons are expanded, they are also confounded with this membrane. 6th. At the two extremities of the ligaments it unites also its fibres to theirs. There are none scarcely except the albuginea, the perichondrium of the larynx, the membranes of the spleen and the kidney, that form an exception to this general rule.

The fibrous system should be considered then in a general manner, that is to say, as extending itself everywhere, belonging at the same time to many organic apparatus, distinct in each by its form, but continuous in the greatest number, having everywhere communications. This manner of describing it will appear still more natural, if we consider that the periosteum, the general boundary of the different portions of this system, is itself everywhere continuous, and at the place where the articulations divide it, the fibrous capsules and the ligaments serve, as we have said, to reunite it.

We understand from this use of the periosteum in relation to the fibrous system, what the advantage is of its situation upon the bones which offer it a solid support, and give the same also to the organs of which it is the boundary.

ARTICLE SECOND.

ORGANIZATION OF THE FIBROUS SYSTEM.

In the midst of the varieties of form that we have just examined, the general organization of the fibrous organs is always nearly the same. I shall now consider this organization; I shall treat elsewhere of the varieties it experiences in each part. It arises from the union of a peculiar texture and of the vascular, cellular systems, &c.

I. _Of the Texture peculiar to the Organization of the Fibrous System._

Every fibrous organ has for a base a fibre of a peculiar nature; hard, but slightly elastic, insensible, scarcely at all contractile, sometimes in juxta-position and parallel to each other, as in the tendons and the ligaments, sometimes crossed in various directions, as in the membranes, the capsules, the fibrous sheaths, &c. but everywhere the same, everywhere of a white or greyish colour, and of a remarkable resistance.

This resistance of the fibrous texture enables all the organs that it composes to support the greatest efforts. Thus these organs are all destined to uses which require this faculty in them. The ligaments forcibly retain the articular surfaces in their proper relation. The aponeuroses confine the muscles and oppose their displacement. The tendons constantly exposed to the contraction of these organs, are at every instant placed between the strong power that they represent and the more or less considerable resistance situated at the extremity of the muscles, &c. Such is this resistance, that it is often greater than that of the bones themselves. We know that by muscular efforts alone, the patella, the olecranon process and the os calcis are sometimes broken; now this could not happen, if the extensor tendons, which corresponded to these different bones, were of a texture that could be more easily torn.

It is to this resistance that must be attributed the following phenomena: 1st. We experience the greatest difficulties in making luxations in the dead body, principally in the articulations called enarthrodial. 2d. In the living subject the external efforts are rarely sufficient to produce them; it is necessary that the powerful action of the muscles should be added. 3d. The punishment formerly employed, of drawing the limbs of criminals by attaching horses to them, was much more terrible, because the resistance of the ligaments made it continue longer; almost always the horses were unable to produce the separation of the extremities; it was necessary that a cutting instrument should assist their efforts. 4th. Weights suspended to a tendon do not break it unless they are enormous; thus the best strings to be employed in the arts would be these textures of the fibrous organs, if drying did not take from these organs their softness and flexibility, if moisture did not alter them, &c. 5th. We cannot without great efforts tear an aponeurosis, especially those of any thickness, as the fascia lata, the albuginea, the dura-mater, &c.

Yet this resistance is sometimes overcome in the living body, and we sometimes see the rupture of the tendons of the solæus, of the small plantaris, of the extensors of the thigh, &c. How does it happen, that the softer texture of the muscle never yields, whilst that of the tendon much more compact is broken? It is because in these cases the fleshy fibres are always in contraction; consequently far from being stretched, as the tendinous fibres are which are then found, if we may so say, passive, their different portions make an effort to approximate each other; and they do in fact approximate; this gives to the muscle a density and hardness equal, and in some cases even much greater, than those of their tendon, as we can ascertain by applying the hand upon a muscle in contraction. A proof that this kind of ruptures is owing to the cause I have mentioned, is this, that if in a dead body we suspend a weight to a muscle detached from the bone at one of its extremities, it will be the fleshy and not the tendinous portion that will break.

The fibrous texture has been considered by some anatomists, as being of a nature approaching that of the muscular texture, and even as being sometimes the continuation of it. Thus they have said that the tendon was formed only by an approximation of the fleshy fibres, which, without changing their nature, only lose their redness. Thus the aponeuroses of covering have been described as an effect of the pressure of the surrounding bodies upon the most external fleshy fibres. In order to see how little foundation there is for this opinion, it is sufficient to observe, 1st, that the dura-mater, the sclerotica, the periosteum, the ligaments, are evidently of the same nature as the tendons and the aponeuroses, and that yet they differ wholly from the muscular texture; 2d, that the chemical composition, the vital properties, the apparent texture, are entirely different in the tendinous and muscular fibre; 3d, that there is no relation between their functions. There is certainly less analogy between the muscle and the tendon which receives its insertion, than between that and the bone which furnishes an attachment to it, and whose cartilaginous portion approximates it in its nature. A muscle and its tendon form an organic apparatus and not a simple organ.

What is the nature of the fibrous texture? We know not, because we do not know any of its properties that are characteristic; it has only the negative ones of those of the muscular texture which is distinguished by contractility, and of those of the nervous texture which is characterized by sensibility. We always see it in a passive state; it obeys the action that is imparted to it, and has scarcely any of its own.

It establishes a great difference between the organs in which it exists and the skin, the cellular texture, the cartilages, the serous membranes, &c.; thus it was wrong to refer all these parts to one and the same class designated by the name of the white organs, a vague term that is only founded upon external appearances, upon the approximation of analyses yet incomplete, and not upon the texture, the vital properties, the life and the functions of the organs. Fourcroy foresaw that this extremely general division would be abandoned after further experiments.

However this may be, the following are the results which the fibrous texture gives when subjected to maceration, ebullition, drying, the action of the acids, &c.

Exposed to maceration in a moderate temperature, the fibrous texture remains a long time without undergoing any alteration; it preserves its size, form and density; gradually this last diminishes; the texture softens; but it does not dilate and swell up; its fibres can then be separated from each other; we see distinctly between them the cellular texture that unites them. Finally at the end of a very long time, they become changed into a soft, whitish pulp, which appears to be homogeneous. All the fibrous organs do not soften equally quick in this way. The tendons are the first to yield to maceration. Then come the aponeuroses; among these, those which are formed by the expansion of a tendon, soften quicker than those destined to cover the limbs, as the fascia lata, for example. The fibrous membranes, the capsules and the sheaths of the same nature are more resisting. Finally the ligaments yield the slowest to the action of water which tends to soften them; yet when they come originally from a tendon, as the inferior ligament of the patella, they are more easily macerated. I have made comparatively, experiments upon all these organs; they give the results that I have stated.

Every fibrous organ plunged into boiling water, or exposed to great heat, crisps and contracts like most of the other animal textures; it diminishes in size, hence it is more solid; it becomes elastic which it is not in the natural state, and afterwards it ceases to be so when it becomes softer before passing into the gelatinous state. By placing all the parts of this system at the same time in water which is made gradually to boil, we see that this softening comes upon all at the same degree, and with nearly the same force. This force, which tends then to make the fibres of this system contract is very considerable; it is sufficient to break at the place of their attachments, those of the periosteum which it raises, by this mechanism, from all the bones that have been boiled for a length of time; to detach the interosseous ligaments, the obturator membrane, &c. when we plunge them into boiling water, with the bones to which they adhere; to contract so strongly the articular surfaces against each other, that they cannot be moved, when, surrounded with their ligaments, they have been exposed to the concentrated action of caloric.

The fibrous texture gradually softens in water, becomes yellowish, semi-transparent and finally melts in part. By boiling together all the parts of the fibrous system, I have observed that the tendons soften first, then the aponeuroses, then the membranes, fibrous capsules and sheaths, and finally the ligaments, which are, as in maceration, those that yield last. Many have already made this remark, to which I add that all do not yield equally. Those placed between the layers of the vertebræ are the most tenacious; they do not take that yellow colour, that semi-transparency, common to all the fibrous system when boiled; they remain white and tough; they appear to contain much less gelatine, and to be entirely different in their nature.

Exposed to the action of the air, the fibrous system loses its whiteness by the evaporation of the fluids it contains; it acquires the horny hardening, becomes yellow, in part transparent and breaks with facility. Some days after having been dried, if replunged into water, it becomes nearly as white and soft as it was before; so that we can truly say, that its white colour is owing to water alone; this phenomenon takes place especially in the tendons. I have observed also in these last another remarkable phenomenon; it is that when they have macerated for some time, and are afterwards dried, they do not become yellow in drying, but remain of a very decided white. Without doubt the whole fibrous system would do the same.

The action of sulphuric and nitric acids quickly softens the fibrous texture, and reduces it to a kind of pulp, blackish in one and yellowish in the other; at the instant we plunge this texture into the acid, it crisps and contracts as in boiling water.

The fibrous texture resists in general putrefaction less than the cartilaginous; but it yields to it more slowly than the medullary, the cutaneous, the mucous, &c. In the midst of these putrid and disorganized textures in the subjects in our dissecting rooms, we find this still untouched; it finally becomes changed also. Water in which it has been macerated gives an odour less offensive than that which has been used for the maceration of most of the other systems.

More digestible than the cartilages and the fibro-cartilages, the fibrous texture is less so than most of the others. The experiments of Spallanzani and Gosse prove this. It appears that it yields to the action of the digestive juices in the same order as to maceration, ebullition, &c.; that is, 1st, the tendons; 2d, the aponeuroses; 3d, the different fibrous membranes; 4th, the ligaments, which are the most indigestible. I would observe however that when boiling has once softened the fibrous texture, it is all digested nearly alike. Thus the cartilages are as easy, and even more so, of digestion, than the tendons, when they have become gelatinous, as Spallanzani proved upon himself, though when raw they are much more indigestible.

II. _Of the Common Parts which enter into the Organization of the Fibrous System._

The cellular texture exists in all the fibrous organs; but it is more or less abundant according as the fibres are more or less distant. In certain ligaments, it forms for the fibrous fasciæ, sheaths analogous to those of the muscles; in others, in the tendons, the aponeuroses, &c. we hardly perceive it; but everywhere it becomes very evident by maceration, by morbid affections, as, for example, by the fungi of the dura-mater, by the carcinoma of the testicle, which has seized the albuginea, by certain swellings of the periosteum, &c. In all these cases the fibrous texture relaxed, softened, preternatural, and of a spongy nature permits its fibres to separate and the cellular organ to appear. The development of fleshy granulations, the soft nature which these granulations have in certain wounds in which the fibrous organ is concerned, prove also the existence of the cellular organ there, which is in general in small quantity; this does not contribute a little to produce the resistance and the force of the organs that belong to it. Does this cellular texture contain fat? At first view we can hardly observe it, since we can scarcely distinguish this texture. Yet I have many times observed that by submitting to desiccation portions of aponeuroses, periosteum, dura-mater, &c. entirely stripped of every foreign part, when all these fluids had evaporated, and the organ had the appearance of parchment, a fatty exudation remaining on many places on its surface.

The existence of vessels varies in the fibrous system; much developed in some organs, as in the dura-mater, the periosteum, &c. they are less so in others, as the aponeuroses, and not at all in some, as the tendons. I would observe in general that it is in those in which they are the most evident, that inflammations and the different kinds of tumours are the most frequently observed. The affections of the dura-mater, the periosteum, &c. compared with those of the tendons, are a remarkable proof of this.

I do not know that absorbent vessels have been traced in the fibrous system.

The nerves appear to be equally foreign to it, notwithstanding what has been written on those of the periosteum, the dura-mater, &c. &c.

ARTICLE THIRD.

PROPERTIES OF THE FIBROUS SYSTEM.

I. _Physical Properties._

The fibrous system has but a slight degree of elasticity in the natural state; but when its different organs are taken from the body and dried, they acquire it very considerably; thus the tendons, the aponeurotic expansions, &c. which in a fresh state would be incapable of any vibration, are found to resound in instruments when they are very dry.

II. _Properties of Texture._

The properties of texture are evident in the fibrous system, but they are less so than in many others.

Extensibility is seen in the dura-mater, in hydrocephalus, in the periosteum; in the different enlargements of which the bones are susceptible; in the aponeuroses, in the swelling of the extremities, and the distension of the abdominal parietes, which, as we know, are aponeurotic as well as fleshy; in the fibrous capsules, in articular dropsies; in the tunica sclerotica and albuginea in the swelling of their respective organs.

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.

These organs are not, like those around which the serous surfaces are spread, as the stomach, the intestines, the bladder and the lungs, subject to alternate dilatations and contractions. This would not accord with their degree of extensibility. They are fitted exactly to the form of these organs, and have none of those numerous folds which we see in the serous membranes, if we except however the dura-mater. Their two surfaces are adherent; a character which distinguishes them especially from the preceding membranes, as well as from the mucous.

One of these surfaces, intimately united to the organ, appears to send various elongations into it, which identify at first view its existence with that of the membrane. Many fibres detached from the albuginea, from the covering of the corpus cavernosum, from the peculiar tunic of the spleen, &c. or rather adhering to these tunics, penetrate the respective organs of these membranes, and crossing there in various directions, form as it were the outline and frame, around which are arranged and supported the other constituent parts of these organs, which seem from this to have the external membranes for a mould; as we see when these moulds are removed, irregular vegetations shooting up here and there. The callus, in displacements too great to allow the periosteum to extend over the divided surfaces, is rough and uneven. The form of the testicle alters, when the albuginea has been divided at any part. This adherence of the fibrous membrane which covers different organs, to the internal elongations of these organs, and the fibres which compose their outline, has made anatomists believe that the nature of one was the same as that of the others, that these were but elongations of the membrane. I thought so when I published my Treatise on the Membranes; but new experiments have since convinced me of the contrary.

I am confident that the membrane of the corpora cavernosa belongs to the fibrous system alone. The internal spongy texture, contained in the cavity of this membrane, has not the nature of it, is not as all anatomists say an elongation of it. The spongy texture is not made by laminæ, which, according to the common expression, are detached from the membrane and produce it by their interlacing. This is a separate body, unlike in its life and its properties.

By exposing a corpus cavernosum to ebullition, I have evidently observed this difference; the external membrane does, like all the fibrous organs, become thick, yellowish, semi-transparent, then melts more or less into gelatine; the spongy texture, on the contrary, remains white, soft, does not increase in size, hardly crisps at all from the action of fire, exhibits, in a word, an appearance which I can compare to no texture treated in the same way by ebullition.

Maceration also answers very well to distinguish these two textures. The first yields but slowly to it; its fibres remain a long time distinct; they have still their natural arrangement, when the second is already reduced to a homogeneous, reddish pulp, in which nothing fibrous, nothing organized can be any longer traced. In general, it appears that the spongy texture of the corpora cavernosa is their essential part, that in which the great phenomena of erection take place, that which animates the peculiar kind of mobility which distinguishes it from the other organs. The fibrous shell is only accessory to its functions; it is but a covering; it is only formed to obey in erection the impulse which is communicated to it.

When we expose the corpus cavernosum to the action of the nitric acid, the spongy texture, freed from the blood it contained, becomes of a much deeper yellow than the fibrous membrane; this enables us to distinguish them clearly from each other.

By exposing the testicle to the action of boiling water, we also observe that its internal texture assumes an aspect wholly different from that of its external membrane; it becomes of a deep brown, whilst the other remains white; it does not assume the gelatinous appearance in so decided or in so prompt a manner as that of the corpus cavernosum.

Subjected to maceration, the testicle is also wholly different in its covering and in its internal texture.

The surface of the fibrous membranes, opposite to that which corresponds to their organ, is joined to the neighbouring parts, sometimes in a loose manner, as the covering of the corpus cavernosum, sometimes by very tight bands, as the dura-mater. In general the membranes, and even all the fibrous organs, have a singular tendency to unite intimately to the serous and mucous surfaces. We find examples of this in the serous membranes in the union of the dura-mater with the arachnoides, of the albuginea with the tunica vaginalis, and the fibrous capsules with the synovial. Such is the intimacy of this adhesion, that the most careful dissection cannot destroy it in adult age. In infancy, it is much less, as we see very well especially in the relation that exists between the base of the pericardium and the phrenic centre, a relation which is such, that we can with ease separate in the first age the two surfaces which are rather contiguous than continuous, whilst in the after ages we are unable to do it.

As to the union of the mucous surfaces with the fibrous, when they are found contiguous, they are entirely confounded; this is observed in the pituitary membrane, in that of the sinuses, of the ear, &c. The perichondrium of the larynx and of the trachea is only a part of their internal membrane. In all these parts, the periosteum so intermixes with the mucous surface, that it is impossible to separate them, and they are removed together from the bone, which then remains bare. The vas deferens, the fallopian tubes, the ureters, &c. are also very evidently fibro-mucous.

II. _Organization of the Fibrous Membranes._

The fibrous membranes have in general a very compact texture, of a remarkable thickness; they are formed only of a single lamina. The dura-mater seems to be an exception to this rule, as its folds form the falciform process and the tentorium cerebelli; but except at the place of the sinuses, it is difficult and even impossible, to find two distinct laminæ.

These membranes have more vessels than all the other divisions of the fibrous system; they are perforated by a great number of foramina for the passage of these vessels, most of which only pass through them, and afterwards go to the organs they cover. These foramina, each of which is larger than the branch it transmits, form also a character of the fibrous membranes, distinct from the serous, which are always folded up, and never open to allow the vascular system to penetrate their respective organs.

The particular description however of the membranes of which we are treating, will be added to that of the organs they surround. I shall except the periosteum, whose description belongs to and may be made in a general way, whether because clothing the whole osseous system, we cannot consider it separately, or because, as I have said, it is the centre from which arise and to which go all the organs of the fibrous system, so that its functions relate still more to this system than to that of the bones.

III. _Of the Periosteum. Of its Form._

This membrane surrounds all the bones. Hard, resisting, of a grey colour, it forms for them a covering which extends everywhere, except where the cartilages cover them. Its thickness is remarkable in infancy; it is thinner in proportion in the adult and becomes more firm and compact.

The ancients described it as extending from one bone to another over the articulation, and thus forming a continuous sac for the whole skeleton. This idea is incorrect. At the junction of the bones, the periosteum intermixes with the ligaments which serve it as a means of communication, and it is in this way only that we can understand its continuity. The crown of the teeth is destitute of it, as well as all the osseous productions that grow upon the head of certain animals.

The periosteum is feebly united to the bone in infancy; it can then be separated with great ease, especially on the middle part of the long bones. In the adult, as the calcareous substance gradually encrusts its most internal fibres, the adhesion becomes very strong; it is extreme in old age, in which this membrane is often reduced to a very delicate layer by the progress of ossification. The constant pressure exerted by the muscles in their contractions, can also have a little influence upon this adhesion. Various elongations pass from the periosteum to the bone. They are much more numerous at the extremities of the long bones and upon the short bones, than upon the middle of the long bones, or the broad ones; which may easily be conceived of, from the much greater number of foramina in one than the other part. These elongations accompany the vessels, line the canals which pierce through the bone, are lost in those which terminate in its substance, do not penetrate the medullary cavity, and confined to the osseous texture alone, establish, between it and the membrane from which they arise, immediate relations.

It is the destruction of these relations, when the periosteum is diseased or destroyed for a considerable extent, that produces the death and separation of the bone. There is however this difference between this phenomenon and the death of the bone by the injury of the medullary membrane, that if this is disorganized, necrosis seizes upon the whole bone, whilst if we irritate and tear the periosteum in the middle part of a long bone, for an extent nearly equal to that of this medullary membrane, the external laminæ of the compact texture alone are detached by exfoliation, and the bone remains the same. I have made this experiment the year past upon two dogs. As to that which consists in removing the periosteum, not only from the middle part, but from the whole surface of the bone, I do not know that any one has been able to try it; it has appeared to me impossible; it might be practicable, but the animal would soon die from the extent of the injury, and thus we could have no result from it.

The relations of the periosteum with the neighbouring organs vary remarkably. In the greatest number of bones, there are muscles that slide upon it; the cellular texture unites it to them more or less closely according as the motions are more or less considerable. In consequence of inflammations, it loses this laxity, and often all motion ceases.

_Organization of the Periosteum._