Inflammation in fibrous structures is a frequent result of stretching and various kinds of injury, as well as of mere exposure. Not less frequently it extends to them from other organs, such as bones and parenchymatous structures, in which inflammation or suppuration is taking place; and, as fibrous structures sometimes lie immediately beneath a serous membrane, they may become involved in an inflammation of it in the way described at p. 30. Lastly, fibrous structures may themselves inflame: in which case, several parts of the system are usually attacked, either together or in succession. Inflammations of this kind are attributed to rheumatism, and to many other constitutional maladies which are described as gout, syphilis, and so forth, but they still require much elucidation.

Inflammation in fibrous tissue is sometimes an acute disease, but very frequently its course is chronic. Its characters are as follow:

It begins with the appearance of streaks of injection, and here and there of red dots which consist of small quantities of extravasated blood: the diseased structure loses its peculiar lustre, and becomes tumid, being infiltrated with a fluid of a grayish or yellowish color, and partly jellylike and coagulating. If the inflammation be violent, it gradually obliterates more and more, the longer it continues, all appearance of fibrous texture; the structure becomes easily lacerable, and the inflammatory product in it, most of which has coagulated, changes its color to a dirty yellowish-red, or reddish-brown. In this state it resembles, as has been remarked by Gendrin, an inflamed lymphatic gland, - i. e. chronic inflammation of a gland.

The neighboring tissues always share in the inflammation of a fibrous structure, but their relations to each other are altered in various ways. The homologous cellular tissue adjoining is usually inflamed in a considerable degree; and it becomes so confounded with the fibrous tissue, that the limits of either cease to be distinguishable. It is in this manner that inflamed fibrous structures - tendons and ligaments - are sometimes fixed in their bed of cellular tissue. But inflamed periosteum, on the other hand, and inflamed dura mater may be easily separated from the bone to which they belong; and some of the tunicae albugineae can be torn from their proper parenchyma, as if it were heterologous tissue. The loosening of the connection is proportioned to the acuteness and violence of the inflammation in the fibrous structure.

If inflammation attack any fibrous structure, such as the dura mater or the capsule of a joint, in consequence of its being laid bare and exposed to contact with the air, it first becomes reddened, dull and villous, and then granulations appear on its exposed surface, which unite with it into a uniform, red, flesh-like, soft mass. Sometimes, especially in tendons, this does not take place until a superficial layer has perished and been cast off". The granulations change into cicatrix tissue, and by it the fibrous structure unites with, and is fixed to, the cicatrix in the other injured organs, muscles, integuments, etc.

There are numerous terminations of inflammation in fibrous structures, and their occurrence is determined by various circumstances.

Suppuration ensues chiefly when the inflammation has been caused by exposure to the atmospheric air, and various other external irritants.

And, under similar circumstances, the inflammation leads to ulceration. Such is the result of inflammations which have been produced by the advance of some neighboring ulcerative process to the fibrous structure; as is instanced in ulcerations of periosteum or of the dura mater, when caries encroaches upon them; or of fibrous capsules, when suppuration is taking place in the serous and synovial membranes which adjoin them. The suppuration and ulceration, in such cases, mostly advance from the surface to the deeper parts of the fibrous tissue; while, at other times, collections of pus and sanies are found in its interior. An ulcer in fibrous structures sometimes has a sarcomatous or fungous appearance, in consequence of the flesh-like substance with which the tissue around it is infiltrated, and of the granulations which project from it.

Slight relapsing inflammations, and those which run a chronic course, end in induration and thickening. The soft, red, flesh-like tissue, infil-tered with inflammatory product, becomes pale and contracted, and gradually changes to a white, dense, firm, fibroid mass, which looks like cartilage. This mass generally unites closely with any neighboring tissue, with bone, for instance, which has been inflamed at the same time, and can then be separated from it only with much difliculty; but the adhesion afterwards becomes much less strong, and may, indeed, at length be entirely destroyed, if the change now described in a fibrous membrane, and the contraction and obliteration of vessels to which it leads, produce attenuation of the tissue which the membrane encloses, or if, as sometimes happens, the inflammation of an organ enveloped in a tunica albuginea be followed by a secondary atrophy of its parenchyma.

Fibrous tissue, when indurated in the manner just described, not un-frequently becomes the seat of ossification: that is to say, of a calcareous deposit. It is observed especially in fascicular structures, such as the ligaments, but is very rarely met with in fibrous membranes, though we find it now and then in the dura mater.

Primary inflammation of a fibrous tissue very seldom terminates in gangrene; but it is a frequent occurrence when other neighboring structures, integuments, cellular tissue, muscles, etc, are sloughing too: it is so in the instance of bed-sloughs. The natural fibrous tissue changes into a blackish-brown mass, which is soaked through with sanies of the same character, is as soft as tinder, and may be torn in any direction. It degenerates in the same manner when it has been crushed or stretched, or when those tissues which convey its bloodvessels are torn off from it, and particularly when the removal of the cellular tissue exposes it to the external air.

Inflammation frequently takes place in periosteum. In its origin and character it corresponds with what has been said of inflammation of fibrous structures in general. It may coexist, even from its commencement, with inflammation of the bone, but it often originates as a substantive disease in the periosteum itself, and in that case always extends to the surface of the bone; or again, it may spread to the periosteum, either from the bone within, or from the soft parts without, especially from cellular tissue, ligaments, and fasciae.

It is distinguished by the same characters as inflammation of other fibrous structures. The membrane unites closely with the cellular tissue which takes part in the process, and thus with the adjoining structures, with sheaths of muscles, aponeuroses, integuments, etc.: but from the bone it can be stripped with ease, especially if the inflammation have been at all intense, or have extended along the prolongations of the membrane into the bone, and have led to any exudation on its inner surface. Sometimes, indeed, the periosteum is found separated from the bone by a considerable quantity of purulent or sanious exudation.

Under whichever of the above-named conditions inflammation of periosteum occur, it frequently proceeds to suppuration and ulceration. There are various ways in which these results may ensue: sometimes they commence at the outer surface of the membrane, sometimes in its interior, sometimes between it and the bone; sometimes again they take place in circumscribed spots, which gradually enlarge and coalesce, while at other times extensive tracts of the membrane are found rapidly undergoing solution. (Schmelzung).

Periosteum is easily replaced when it has been lost by injury; and even when it has been destroyed by ulceration, so soon as the constitutional cause of the inflammation of the bone has ceased. The new membrane is formed out of a plastic exudation from the bone.

Chronic inflammation often leaves behind it thickening and induration of the periosteum. That membrane is then found changed into a whitish layer, which may be several lines in thickness: its texture is very close, and it is as tough as leather, or fibro-cartilage. It adheres closely to the-bone, and seems intimately united with it. The condition of the bone under such circumstances varies considerably, and will be described in another chapter.