A text book of physiology / by William Rutherford.

Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: A text book of physiology / by William Rutherford. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    nip the muscle. When the muscle contracts and widens the forceps, air is pressed from the tambour (m) into the second tambour (t), on the membrane of which there rests a lever for recording the muscular movement. Single contractions are obtained by transmitting single induction shocks through the muscle. Fig.. 130 shows a curve of a single contraction of the ad- ductor of the thumb taken on the pendulum myograph with the above arrangement. The stimulus was an opening induction shock of moderate intensity sent through the muscle at s. The curve of contraction is similar to that of the frog's muscle when registered by a light lever. In tliis experi- ment the latent period was sec, and the duration of the con- traction (the second event) -gV sec, but doubtless both periods vary with the strength of the stimulus, as in the frog's muscle. The duration of a single contraction varies much in different muscles of Fig. 130.—Single contraction of human voluntary muscle induced by an opening induction ,shock sent through the muscle at s. 1, 2, 3, 4 are the events that follow the stimulation before referred to ; a, abscissa. the same animal, and in different animals; thus it is shortest in the striped skeletal muscles (about Jg- sec), about eight times as long in the striped muscle of the heart, and still longer in non-striped muscle. It is nearly twice as long in the red as compared with the pale muscles of the rabbit (see p. 132) (Eanvier, Op. 11, 1874, p. 5). It is about five times longer in the hyoglossus than in the gastrocnemius of the frog (Marey, Op. 74, p. 364). It is shortest in insects and longest in the tortoise (Marey, Op. cit.) As regards rapidity of contraction, the ordinary striped muscle of different animals may be arranged in the following order, beginning with the slowest:—the tortoise and hybernating mammals, the frog, mammals, fishes, birds, insects (Marey, Op. cit.) The duration of contraction is lengthened by fatigue, and especially by cold. The difliculty in executing delicate movements when the hands Fig. 129. Marey's myographio forceps applied to adductor of thumb; m, tambour of the forceps ; (, tambour with recording lever.