Crurotarsal

From Wikipedia, the free encyclopedia

A crurotarsal ankle is one which can bend between the astragalus and calcaneum.[1] Crocodilians and therian mammals (marsupials and placentals) have crurotarsal ankles, but these work in very different ways:

Therian form of crurotarsal ankle. Adapted with permission from Palaeos
Therian form of crurotarsal ankle. Adapted with permission from Palaeos
  • In the therian crurotarsal ankle, the main joint bends between the tibia and astragalus; the calcaneum has no contact with the tibia but forms a heel to which muscles can attach.


Crocodilian form of crurotarsal ankle. Adapted with permission from Palaeos
Crocodilian form of crurotarsal ankle. Adapted with permission from Palaeos
  • In the crocodilian crurotarsal ankle, the astragalus is fixed to the tibia by a suture and the joint bends around a peg on the astragalus which fits into a socket in the calcaneum.


[edit] References