A median sternotomy is the medical procedure by which the sternum, or breastbone (the bone that runs down the middle of your chest) is cracked open by a surgeon in order to have access to the major thoracic organs (the heart and lungs primarily.) It is used in all open-heart surgeries, although sternomoties are required for other, non-heart-related surgeries as well.

In a sternotomy, the an incision is made along the sternum using a bone saw, and then a retractor is placed within the incision, which then proceeds to crack and then divide the sternum into its respective halves. From there, surgery proceeds.

Once a sternotomy is complete, a surgeon will usually use wire (and occasionally metal plates) to close the sternum and allow it to heal. There are currently many different proposed methods for ideal wiring and reconstruction of the sternum, although the most common one involves a standard "cross-stitch" suturing.

It makes me kind of queasy just researching all of this.