The sternum is a long, flat bone located in the center of your chest. It's also known as the breastbone. Here are some key things to know about it:

* Location: The sternum sits in the front of your rib cage, connecting to the ribs via cartilage.

* Shape: It's roughly shaped like a tie, with three parts: the manubrium at the top, the body in the middle, and the xiphoid process at the bottom.

* Functions:

* Protection: The sternum protects your heart and lungs from injury.

* Attachment point: It provides a strong anchor for muscles involved in breathing, moving your arms, and supporting your chest wall.

* Bone marrow production: Like other bones, the sternum contains bone marrow, which produces blood cells.

If you meant "stemum" for a different reason, please let me know! I'm happy to help.