The meaning of ‘myo’ is ‘muscle’, and ‘genic’ is ‘originating from’. The human heart’s contraction is activated by a specially modified heart muscle known as the sinoatrial node that is located in the right atrium. The SA node has the inherent power of generating a wave of contraction and controlling the heartbeat. Thus, it is known as the pacemaker. As the SA node initiates a wave of contraction and controls the heartbeat, the contraction’s impulse originates in the heart itself; the human heart is termed myogenic. The hearts of vertebrates and molluscs are also myogenic.