.317 



We cannot admit, with Pouteau, that the muscles of the limbs, though 

 applied to the bones by aponeurotic coverings, can become displaced, so 

 as to form herniae. When they contract in a wrong 1 position, some fib- 

 rillce are torn, and this gives rise to most of those momentary and very 

 sharp pains called cramp. I have, at present, before me, the case of a 

 young girl, in whom the aponeurosis of the leg, exposed in conse- 

 quence of an extensive ulceration, exfoliated from the middle and fore 

 part of the limb to the instep. This exfoliation was accompanied by a 

 displacement of the tibialis anticus of the extensors of the toes; the leg 

 is become deformed, the motions of extension of the foot and toes are per- 

 formed with difficulty, and will soon become impossible, when the exfoli- 

 ation of the tendons follows that of the aponeurosis which protected them 

 from the air. 



CLXIII. When a muscle contracts, its fibres are corrugated trans- 

 versely, its extremities are brought nearer to each other, then recede, and 

 again approach towards one another. These undulatory oscillations, 

 which are very rapid, are followed by a slighter degree of agitation ; the 

 body of the muscle, swollen and hardened in its decurtation, has acted on 

 the tendon in which it terminates ; the bone to which the latter is connect- 

 ed is set in motion, unless other agents, more powerful than the muscle 

 which is in action, prevent its yielding to that impulse. Such are the 

 phenomena exhibited by the muscles exposed in a living animal or in 

 man, when their contractions are brought on by the application of a sti- 

 mulus. But these contractions, determined by external causes, are never 

 so strong or instantaneous, as those which are determined by the will, in 

 a powerful arid sudden manner. When an athletic man reduced by ill- 

 ness, powerfully contracts the biceps muscle of the arm, this muscle is 

 seen to swell suddenly, to stiffen and to continue motionless in that state 

 of contraction, as long as the cerebral influence, or the act of the will, 

 which determines it, lasts. 



Though the muscles manifestly swell in contracting, and though the 

 limbs are confined by the ligatures applied round them, the whole bulk 

 of the contractile organ diminishes: it loses in length, more than it gains 

 in thickness This is proved by Glisson's experiment which consists in 

 immersing the arm in a vessel filled with a fluid, which sinks when the 

 muscles act. We cannot, however, estimate the diminution of bulk, by 

 the degree in which the fluid sinks, since that effect is, in part, owing to 

 the collapse of the layers of the adipose tissue, which is compressed in the 

 muscular interstices. 



A sound state of the vessels and nerves distributed to muscles is indis- 

 pensible to their contraction. If the free circulation of the blood or of 

 the nervous fluid is prevented, by tying the arteries or nerves ; if the re- 

 turn of the blood, along the veins, is prevented, by applying a ligature to 

 these vessels, the muscles will be completely palsied. By dividing or ty- 

 ing the nerves, the action of the muscles to which they are distributed, 

 is suddenly interrupted. The same effect may be produced by intercept- 

 ing the course of the arterial blood, though in a less rapid and instanta- 

 neous manner; and it is very remarkable, that it is equally necessary that 

 the veins should be as sound as the arteries, to enable muscular action to 

 take place. Kaaw Boerhaave ascertained, by actual experiment, that when 

 a ligature is applied to the vena cava, above the lilacs, paralysis of 

 the lower extremities is brought on, as when the aorta is tied, as was 



