Frequently in old age the muscular texture loses its colour and takes a yellowish one and has a fatty appearance, though however this colour does not arise from the fat, but from the absence of the colouring substance of the blood. I have often made this remark. If we strip all the surrounding fat from these pretended fatty muscles, and leave them only their texture, combustion or ebullition extracts no animal oil from them; they are in their fibrous state as usual; the colour only is different. I have remarked that the deep muscles of the back and those placed in the vertebral depressions are much more subject than all the others to lose their colour and to exhibit this yellowish aspect, an aspect that is rarely ever seen in the whole system, but only in some insulated muscles. Adults are subject, though less frequently however, than old people, to this alteration. Many times we see limbs that are poorly nourished, with an aspect, nearly the same. In recent palsies, in those even of three, four or six months, there is in general no change in the limbs; the muscles preserve their colour and their size; but at the end of a longer time, the absence of motion, perhaps also the deficiency of nervous influx, terminate by altering the nutrition left for a long time untouched without this influx, and then the muscles change colour, contract and diminish. But this phenomenon is not always constant, and there are at the Hôtel-Dieu hemiplegias of six, seven and even ten years, without the limb of the sound side predominating in its nutrition over that of the diseased one.
External pressures for a long time continued upon a muscle, produce nearly the same effect as want of nourishment; they discolour and whiten it by preventing the circulation in it. Those who make use of straps constantly passed under the arms, who habitually have girdles round the abdomen and who lift burdens, have often the muscles corresponding to the constant pressure they experience, in the state of those of old people. I would remark that these muscles contract notwithstanding; which proves that the colouring substance is not of absolute necessity to muscular action.
The blood is carried in general in much less quantity in the muscles of old people; their vessels are in part obstructed; this is what disposes them to the state of which I have just spoken.
V. State of the Muscular System at Death.
At the instant of death, the muscles remain in two different states; sometimes they are stiff and inflexible; sometimes they allow the limbs to execute motions very easily. It is sometimes necessary to make an effort to bend the thigh of a dead body; at others the least touch is sufficient to do it, as for example in asphyxia, from charcoal. These state of rigidity and relaxation have infinite degrees. The first is sometimes so great, that the subject raised against a wall remains standing; at other times it is nothing. Some muscles are stiff in subjects, while others are relaxed. It appears that these different states depend upon the kind of death, upon the phenomena that accompany the last moments. But how do they precisely happen? It is an object of interesting research. I have remarked that the muscles remaining stiff at the instant of death, are often torn with ease, if we attempt to force the motions of the limbs to which they go; that the tearing hardly ever takes place on the contrary in those remaining supple, whatever may be the impulse communicated at their moveable points; it is necessary to draw them directly, attach weights to them, &c. to produce this phenomenon, which is then easy.
The muscular texture is never preternaturally developed in the different organs in which nature has not originally placed it, as happens in the osseous, cartilaginous and even fibrous textures. If it were developed, it would not belong to animal but to organic life; because in order to depend upon the first, the cerebral nerves are essentially necessary, the muscle being but the agent of the motions which the latter communicate.
END OF VOL. II.