Astragalus – calcaneum
i) It is a compound bone of the ankle of hind-limb.
ii) The ankle consists of two rows of four bones. The first or proximal row consists of two long bones fused together to their proximal and distal ends with a wide gap in the middle.
iii) The inner bone is thinner and slightly curved called astragalus or tibiale.
iv) The outer bone is thicker and straight called the calcaneus or fibulare.
v) The proximal and distal ends are covered by epiphyses of calcified cartilage.