Under medium to high power magnification through the microscope, you can see small stripes running crosswise in both types. Smooth muscle is nonstriated. Cardiac muscle could almost be said to be a hybrid between skeletal and smooth muscle. Cardiac muscle does have several unique features. Present in cardiac muscle are intercalated discs, which are connections between two adjacent cardiac cells.
Intercalated discs help multiple cardiac muscle cells contract rapidly as a unit.
This is important for the heart to function properly. Cardiac muscle also can contract more powerfully when it is stretched slightly. When the ventricles are filled, they are stretched beyond their normal resting capacity. The result is a more powerful contraction, ensuring that the maximum amount of blood can be forced from the ventricles and into the arteries with each stroke. This is most noticeable during exercise, when the heart beats rapidly.