Anterior mediastinum

The anterior mediastinum exists only on the left side where the left pleura diverges from the mid-sternal line.

It is narrow, above, but widens out a little below.

Boundaries
It is bounded:
 * in front by the sternum
 * laterally by the pleurae
 * behind by the pericardium
 * anteriorly by the left Transversus thoracis and the fifth, sixth, and seventh left costal cartilages

Contents
It contains:
 * a quantity of loose areolar tissue
 * some lymphatic vessels which ascend from the convex surface of the liver
 * two or three anterior mediastinal lymph glands
 * the small mediastinal branches of the internal mammary artery