<P> The muscular system has been similarly modified . The hind limbs of ancestral frogs presumably contained pairs of muscles which would act in opposition ( one muscle to flex the knee , a different muscle to extend it ) , as is seen in most other limbed animals . However , in modern frogs , almost all muscles have been modified to contribute to the action of jumping , with only a few small muscles remaining to bring the limb back to the starting position and maintain posture . The muscles have also been greatly enlarged , with the main leg muscles accounting for over 17 % of the total mass of the frog . </P>
<P> The muscular system has been similarly modified . The hind limbs of ancestral frogs presumably contained pairs of muscles which would act in opposition ( one muscle to flex the knee , a different muscle to extend it ) , as is seen in most other limbed animals . However , in modern frogs , almost all muscles have been modified to contribute to the action of jumping , with only a few small muscles remaining to bring the limb back to the starting position and maintain posture . The muscles have also been greatly enlarged , with the main leg muscles accounting for over 17 % of the total mass of the frog . </P>
where does the frog have the most muscle
where does the frog have the most muscle
main leg muscles
main leg muscles