Figure 1.

Gross anatomy and structure of the Achilles tendon. (A) The Achilles tendon emerges at the distal confluence of the gastrocnemius and soleus muscles and inserts into the calcaneus. (B) Similar to other tendons, the Achilles exhibits a hierarchical structure composed of fascicles, fibers, and fibrils. When loaded, fibrils straighten, decrease in crimp amplitude and frequency, and become more aligned.

Panel A: Image reproduced with permission from Joanna Cameron (2013). Panel B: Image reproduced with permission from Franchi et al. (2007)38 and Voleti et al. (2012)33.