Question

part 2 of 2

Explanation:

The structure pointed to by the question mark in the ribcage diagram is the sternum (specifically the manubrium, part of the sternum). The sternum is a flat bone at the front center of the chest, connecting to the ribs via costal cartilages. In the ribcage anatomy, the upper, wider part of the sternum (manubrium) is visible here, articulating with the clavicles and the first few ribs.

Answer:

The structure is the sternum (manubrium of the sternum).