Observations on the muscles, and particularly on the effects of their oblique fibres : with an appendix.

  • Monro, Alexander, 1733-1817.
Date:
1794
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the muscles, and particularly on the effects of their oblique fibres : with an appendix. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    AD and AE be fuppofed to move the point A to number i, and let the mufcles i D and i E be fuppofed to move number i to number 2, or through a like fpace. It is evident, that in the triangles 1 IE and 2 II E, the angles 1 I E and 2 II E are equal; but as the angle 2 E II is larger than the angle 1 E I, the angle II 2 E mull be lefs than the angle I 1 E. Hence, as the fides of triangles are longer in proportion to the width of the oppolite angles, the lide I E will be longer in proportion to 1 E, than the lide II E is in proportion to 2 E. The mufi- cular fibres, therefore, AD and AE, in bringing the point A down to number 1, will lofe more, in proportion of their length, than the more oblique fibres 1 D and 1 E will do in moving number 1 to number 2. To prove this by calculation, let us fuppofe the mufcle to be ftill reprefented by the hypotenufe of a right angled tri- angle, five inches in length, and capable of Ihortening itfelf one inch, and that one of the other fides meafures four inches, and that the third fide meafures three inches. But let the fide 3 form the balls of the triangle, and the fide 4 its perpendicu- lar, as in T. 2. fig. 7. In this cafe, the fquare of the hypotenufe, when it has Shortened itfelf one inch, will be 16, from which deducting 9, the fquare of the balls, the number 7 remains for the fquare of the perpendicular. But the fquare root of that number being more than 2y, the oblique mufcles, Ihortened one-fifth, cannot bring the point A down it. inch, or to B, or cannot move the point A half fo far as they were fiiewn to do, when the obliquity was greater, by making the balls 4 inches and die altitude 3 inches. Ob