An inquiry into the comparative forces of the extensor and flexor muscles, connected with the joints of the human body / [Julius Jeffreys].

  • Jeffreys, Julius, 1801-1877.
Date:
1822
Catalogue details

Licence: Public Domain Mark

Credit: An inquiry into the comparative forces of the extensor and flexor muscles, connected with the joints of the human body / [Julius Jeffreys]. Source: Wellcome Collection.

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    Hence it is plain that, when these muscles con¬ tract, the lower part of them acts upon the upper part, and depends upon it for support; and, therefore, any piece of one of these muscles, taken transversely, must have as much power as the whole muscle. On the other hand, all the extensors, except the Rectus, arise by numerous fibres the whole way down the femur, and are in¬ serted at numerous points into their common ten¬ don, into the patella, and into the aponeurosis covering the knee. The power of these muscles must he much superior from this circumstance alone. Each part of any of these muscles has an ^origin, and insertion independent of the rest of the muscle, and does not act upon the other part. So that the whole muscle, instead of only equal¬ ling a part of itself in strength*, as is the case with many of the flexors, is actually as much stronger,' as it is larger than its part. * I am well aware that this is 'not] the case with all the flexors, eipe- cially the short head of the biceps and semi-membranosus; even these,however, are far Inferior to the extensors in the advantageous structure described above. c 2
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