Additional muscle in idiopathic club foot.

During the dissection of seven club feet of foetuses, aborted between the 25th and 37th week of gestation, an additional muscle bundle was found in a right foot. This muscle arose from both heads of the gastrocnemius muscle, continued downwards onto the posterior surface of the soleus, crossed the calcaneal tendon and assumed a position on the lateral side of the calcaneal tendon. The muscle's tendon was fixed just laterally to the calcaneal tendon in the calcaneal tuberosity with some tiny fibres branching off into the superior fibular retinaculum.