The sternocostal surface of the heart is directed anteriorly, superiorly and slightly to the left. It is formed by the left, right, superior and inferior borders of the heart.
It consists of the anterior surfaces of the:
- right atrium: to the right and superior to the anterior atrioventricular groove
- right ventricle:
- forms two thirds of the anterior surface
- separated by the anterior interventricular groove from the anterior surface of the left ventricle
- left atrium: minimal contribution; its auricle may overlap the right superior surface of the heart
- left ventricle: forms a small part of the far left sternocostal surface
Anteriorly, the sternocostal surface is separated by pericardium from the:
- posterior of the body of the sternum
- sternocostalis muscle
- third to sixth costal cartilages on the left
- mediastinal pleura
The acute angle at the anterior edge of the lungs fills the pleurae and is almost continuous across the midline except for a small, triangular area on the left of the sternocostal surface. The cardiac notch of the lung borders this laterally.