Talocalcaneal movements in mammals



The movements permitted at the compound talocalcaneal joints of mammals are of two main types: in most species examined, the calcaneus is able to rotate beyond the talus about an oblique axis, whereas in cursorial and saltatory forms rotation tends to take place about a transverse axis, supplementing flexion and extension at the ankle joint. The primitive pattern is exemplified in the foot of the Echidna, in which the ankle joint is ovoid in type and both the talus and calcaneus are able to rotate to produce cupping of the sole. The range of talocalcaneal movement is inevitably limited in those species in which the ancestral calcaneo-fibular contact has been retained.