Answer:
The inner surface of the heart is known as endocardium. The endocardium layer cover the tendons and the heart valves.
It basically attached to the heart with the help of endothelium that continues line the blood vessel.
It is basically made up from the thin layer by using the squamous cell and the areolar tissue, which is same as the epicardium in the heart. It also helps in regulate the overall activities of myocardium from the cells.