Skeletal System:
An amphibians skeletal system’s main purpose is to support the body and to protect the internal organs.
Muscular System:
Frogs have to generate a high level of power to be able to leap. Most of this power is assumed to come from their legs. During the jump, the hind legs provide most of the force but when landing, it extends its forearms and the shoulders absorbs most of the impact.
A Study In Biology 