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.