On the minute structure and movements of voluntary muscle / By William Bowman, Esq., Demonstrator of Anatomy in King's College, London, and Assistant Surgeon to the King's College Hospital.

  • Sir William Bowman, 1st Baronet
Date:
1840
Catalogue details

Licence: Public Domain Mark

Credit: On the minute structure and movements of voluntary muscle / By William Bowman, Esq., Demonstrator of Anatomy in King's College, London, and Assistant Surgeon to the King's College Hospital. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    closely together in the one part, and stretched to a corresponding degree immediately beyond. This first stage is represented in fig. 89. The nucleus of contraction slowly extends itself, by involving a greater length and a greater number of fibrillse, and while doing so, has generally an oscillation along the implicated fibrillse, effected by the alternate attraction and partial release of striae at its opposite ends. It would almost appear as if the contractile force of the spot were limited; able only to engage a certain amount of the mass; so that, as fresh portions were assumed on the one hand, some were relinquished on the other. But the occasion of the oscillation would seem to be the traction of neighbouring points, also active, striving to acquire additional striae; for, as before observed, the cut extre- mities are always the first to contract, and being thereby rendered thicker, are in some measure restrained from approaching each other by the mica or glass, with which it is necessary to cover the object. Be that as it may, the movements are such as to convey the idea of opposing forces struggling for the mastery, and they do not cease till the whole fasciculus is contracted to less than half its original length. They prove incontestably, that the agency in question, whatever it may be, operates primarily on the individual segments of the fibrillae. When a contraction is very forcible and going on at the same moment at several points of a fasciculus, it may happen, if the pressure on the extremities prevents their approximation, that the intermediate flaccid portions are stretched even to laceration, as seen in fig. 75. from the Frog. This fact may serve to illustrate those remarkable cases of musculur rupture from inordinate action, concerning which much has been written*. In the Skate, the following appearances once presented themselves. Dark waves of contraction, caused by the successive approximation and recession of one side of the discs, began to play backwards and forwards along one margin of the fasciculus. These gradually included the whole breadth of the fasciculus, and then coalesced; permanent rugae at the same time forming in addition, each about 4^th inch broad, and including twenty or thirty of the approximated striae. Fig. 88. exhibits these al- terations. A contracted fasciculus has often a somewhat uneven or undulated margin, which is sometimes occasioned by very slight irregularities or puckerings of the fibrillae, but more frequently by a transverse wrinkling of the sarcolemma, which, when this is extensively separated by fluid from the fibrillae, is almost a necessary consequence of * See J. L. Petit; and M. Roulin, Majendie’s Journal, vol. i. p. 295. [I have just been indebted to the kindness of Mr. Busk, surgeon to the Dreadnought Hospital Ship, for an opportunity of examining specimens of muscle, ecchymosed and ruptured by spasmodic action during a rapidly fatal tetanus. We found them to present appearances of disintegration, such as are frequently seen in fasciculi inordinately contracted under the treatment above described, and this to so great an extent, that in many parts neither transverse nor longitu- dinal striae could be discerned, but only a confused mass of primitive component particles, held together by the sarcolemma, as seen in a portion of fig. 37. from the Frog. Other muscles from the same subject, which had been free from spasm, were in all respects natural.—November, 1840.]