Structures and Grooves on the Sternocostal Surface of the Heart
Two grooves divide the sternocostal surface into its chamber regions and carry important neurovascular structures.
1. Anterior Part of the Coronary Sulcus (Atrioventricular Groove)
Position: Runs obliquely across the upper part of the sternocostal surface, separating the right atrium (above) from the right ventricle (below).
Important: The anterior coronary sulcus is interrupted in the middle by the infundibulum (conus arteriosus) of the right ventricle — the smooth outflow tract that leads to the pulmonary trunk.
Contents of the anterior coronary sulcus:
| Structure | Notes |
|---|---|
| Right coronary artery | Runs in the sulcus to reach the right AV groove |
| Right atrial branch of right coronary artery | Supplies SA node |
2. Anterior Interventricular Groove
Position: A groove running from the root of the pulmonary trunk (above) to the apex of the heart (below), along the sternocostal surface. It separates the right ventricle (right/anterior) from the left ventricle (left/posterior).
Contents:
| Structure | Notes |
|---|---|
| Anterior interventricular artery (left anterior descending artery — LAD) | Branch of left coronary artery; most important artery of the heart |
| Great cardiac vein | Runs alongside the LAD, ascending from apex towards the coronary sulcus |
| Adipose tissue | Fills the groove |
3. Infundibulum (Conus Arteriosus)
- The smooth, cone-shaped outflow tract of the right ventricle
- Projects upwards and to the left from the right ventricle, leading to the pulmonary valve and pulmonary trunk
- Its smooth wall lacks musculi pectinati — developmentally derived from the bulbus cordis
- Interrupts the anterior coronary sulcus — the sulcus is not continuous across the front of the heart
Summary Table: Grooves and Their Contents
| Groove | Separates | Contents |
|---|---|---|
| Anterior coronary sulcus (AV groove) | Right atrium from right ventricle | Right coronary artery; interrupted by infundibulum |
| Anterior interventricular groove | Right ventricle from left ventricle | Anterior interventricular artery (LAD); great cardiac vein |
Structures Visible on the Sternocostal Surface — Top to Bottom
| Level | Structures (right → left) |
|---|---|
| Upper | SVC → ascending aorta → pulmonary trunk |
| Upper auricles | Right auricle (over root of aorta) → left auricle (behind pulmonary trunk) |
| Mid surface | Right atrium (right) → infundibulum/right ventricle (centre and left) |
| Lower surface | Right ventricle (right and centre) → left ventricle (narrow strip, left) |
| Groove | Anterior interventricular groove (LAD + great cardiac vein) running to apex |
Clinical Correlation
LAD occlusion (“widow maker”): The anterior interventricular artery (LAD) runs in the anterior interventricular groove. Its occlusion causes an anterior myocardial infarction — the most extensive and dangerous pattern of MI, as the LAD supplies the anterior wall of the left ventricle, the interventricular septum (anterior two-thirds), and the apex.