1. Hemorrhage. Apoplexy

The various solutions of continuity, lacerations, and blows, which happen to muscles, give rise to effusions of blood within them: they are also liable to spontaneous hemorrhages into their parenchyma, - to extravasation of blood into their cellular and aponeurotic sheaths, - in fact to apoplexy. In cases of decomposition of the blood, trifling suffusions or ecchymoses occur in the muscles, as well as in the skin and subcutaneous cellular tissue; but in bad cases of scurvy and typhus, blood is extravasated from the capillaries rapidly and in large quantities, bruising and breaking the muscular fibres. Hemorrhages of this kind occur chiefly in the muscles of the lower extremities and abdomen, and are usually accompanied by effusions of blood into other tissues also.

2. Inflammation

Inflammation of muscle (myositis) not only occurs as a consequence of the various injuries to which these organs are subject, whether incised, lacerated, punctured or gunshot wounds, or crushing, rupture, stretching, mechanical irritation, or concussion; but also arises spontaneously. It is sometimes a primary affection, and is brought on especially by the influence of cold; at other times it is a secondary consequence, either of metastasis, or of inflammation existing in adjoining organs. Its course may be acute or chronic. It is sometimes confined to a few scattered, and mostly small, spots in a muscle; at other times it invades the whole body of one, or of several muscles at once. As the cellular sheaths of the muscular fasciculi are almost always the seat of the process, especially if the inflammation be extensive, the distinguishing features of inflamed muscle will include those which characterize inflammation of cellular tissue. I must, therefore, necessarily refer to the latter, though attention will be chiefly directed to the change in the muscular tissue.

a. At first some redness and injection are perceived, and a little infiltration, of the interstitial cellular tissue; no change is discernible at this period in the muscular fibre itself.

b. But so soon as an actual exudation appears, the muscular fibre becomes discolored; it changes to a pale red, a reddish-yellow, or a fawn color.

c. If the inflammation continue, and the exudation be not absorbed, an important change soon takes place in the texture of the muscle; the fibres lose their transverse striae, and the fibrils degenerate into a granular mass.

d. The exudation presents various, and essentially different characters, some of which are due to the particular cause of the affection, and some to the state of the constitution.

Some kinds of inflammation deposit, in the interstitial cellular tissue, and between the muscular fibres, a gelatinous, grayish or grayish-yellow, product, which gradually solidifies and becomes a whitish lardaceous callus; inflammations of this kind are mostly slow in their course, and are attended by mild symptoms: they are commonly named rheumatic.

The product of another kind of inflammation is reddish or yellowish, and fibrinous, and readily coagulates; it becomes converted into fibroid tissue.

Others, again, lead to a yellow exudation, which degenerates into pus; after a time the product exuded is a fluid, and either purulent or sanious. Inflammations of this character frequently destroy entire muscles.

Lastly, there are some inflammations, the product of which is essentially tubercular, and softens like tubercle.

Now and then, in cases of scurvy, and in inflammations of paralyzed muscles, a sanguineous product is found in the muscular tissue.

e. Under circumstances so various, the appearance of the inflamed muscle differs accordingly; its peculiar characters are most evident, when the inflammation is confined to isolated spots. The muscular fibres are then found in the midst of the exudation, discolored, disintegrated, and forming dull yellowish-red, or fawn-colored, and here and there interrupted, stripes. The exudation in which they lie may be a gelatinous, grayish, or grayish-yellow, substance; or firmer, and reddish or yellowish; or purulent and yellow; or tubercular and cheese-like; or red, filled with blood, and half coagulated.

An inflamed muscle is always somewhat shortened, and is paralyzed in that position; so that the limb in which myositis occurs, is nearly or quite immovable; and if the flexor muscles be affected, it is fixed in the bent position. The muscle is bound also in another way; for its cellular and fibrous investments having taken part in the inflammation, it becomes fixed in its sheath, and thereby also to other neighboring parts, which may have been inflamed with it.

Inflammation of muscle, if it do not subside, may terminate in induration, in suppuration, or in gangrene.

When an intense inflammation subsides, it leaves the muscle wasted; and if there have been extensive inflammations, the whole limb shrinks, and affords an example of secondary atrophy.

Induration is a mode in which inflammation frequently terminates; it is often found to have occurred at some isolated spots, especially in the heart. The exudation in the inflamed part coagulates and becomes converted into a whitish, lardaceous, firm callus, which assumes a fibroid structure, but is still traversed by a few pale and broken muscular fibres. The appearance of the callus varies according to the original quantity of exudation: at first it forms cords and streaks, which ramify amongst the fibres and fasciculi of the muscle, or more extensive, round, or nearly round, masses, which may be tolerably circumscribed, or may branch out irregularly in various directions. In the course of time, it may diminish in size considerably, partly from absorption, partly from its shrinking and becoming more dense, and from the disappearance of the muscular substance that still remains within it. As it thus diminishes in size, it draws in the surrounding tissue, and assumes the appearance of a deep cicatrix.