ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

In the absence of membranes, the muscle fibers are able to shorten easily, without the
transference of stresses to membranes. Consequently, the displacement-field on the
muscle’s surface and the average fiber shortening of the gastrocnemius muscle are too
large. On the other hand, including membranes, the stresses resultant from muscle
activation are transferred to stretch the Achilles tendon. The external Achilles tendon
average strain increased from 0.061 (with membrane model) to 0.074 (without
membrane model) and the Achilles tendon force ultimately increased. Additionally, the
membrane keeps the average fiber strain to around optimum length in this simulation.
Consequently, the active force produced by muscle contraction increases with
membranes in comparison with the model without membranes.
In conclusion, muscles’ membranes, which are difficult to identify from medical
imaging data, play a very important role on the biomechanics of muscles. It is, therefore,
important to take into account muscles’ membranes by coupling the geometrical
reconstruction with a model enhancement from other anatomical knowledge and
considerations, in order to achieve accurate and representative FE models.
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