Why do we call our heart myogenic?

(N/A) In the human heart,the contraction is initiated by a specialized modified cardiac muscle tissue known as the sinoatrial node ($SA$ node).
It is located in the wall of the right atrium.
The $SA$ node possesses the inherent ability to generate an electrical impulse,which initiates a wave of contraction and regulates the heart rate.
Because of this,it is referred to as the natural pacemaker of the heart.
Since the heartbeat is initiated by the $SA$ node and the impulse for contraction originates within the heart muscle itself rather than from the nervous system,the human heart is termed myogenic.
The hearts of all vertebrates and most molluscs are also myogenic.