In frog heart, there are cardiac muscles which consists of fibres...

The heart wall of frog composed of epicardium, myocardium and endocardium. The myocardium is composed of branched and striated yet involuntary cardiac muscles which contracts and relax rhythmically at a fixed rate. The fibres of the self excitatory and conducting muscle of the heart are of three types-nodal fibres, transitional fibres and Purkinje fibres. In frog heart, a number of muscular ridges called columnae carnae projected from the wall of ventricle into its cavity, dividing the peripheral part of the cavity into a number of pockets.