Willis and steno on muscles: Rediscovery of a 17th‐century biological theory*

Niels Stensen in 1667 in the first systematic analysis of muscle fibre contraction described the unipennate actuator of skeletal muscles, now applied in computer programs simulating muscular action. Three years later Thomas Willis partially approved Stensen's description and brought an exact anatomical illustration from an ox, probably drawn by Christopher Wren. This new concept and theory was, however, refuted by Mayow, Borelli, Johann Bernoulli, Boerhaave and von Haller and became almost forgotten until the anatomical rediscovery in 1981.