Man has two lower leg bones, the tibia and the fibula. A third division of the frog's leg consists of two elongated anklebones, or tarsals. These are the astragalus and the calcaneus. The astragalus corresponds to the human talus. The calcaneus in the human skeleton is the heel bone.
Internal organs contain smooth muscle tissue.
The frog heart is the only organ contained within the coelom which has its own protective covering. There are two upper chambers of the heart, the right atrium and the left atrium. The frog heart, however, has only one lower chamber, a single ventricle. In man, the lower heart chamber is divided into two compartments, the right ventricle and the left ventricle. Such mixing is prevented by a unique arrangement of the frog's heart.