The interclavicular ligament is a flattened band, which varies considerably in form and size in different individuals, it passes in a curved direction from the upper part of the sternal end of one clavicle

Clavicle

In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...

 to that of the other, and is also attached to the upper margin of the sternum.

It is in relation, in front, with the integument and Sternocleidomastoidei; behind, with the Sternothyreoidei.