The sternum is the medical name for the breastbone. The breastbone develops from three different parts, one of which is the xiphoid process. The manubrium is the upper portion and the middle is called the middle body. The xiphoid process is the small part at the bottom of the sternum that projects down. It begins as cartilage but by the time a person is middle aged, it turns to bone (ossifies) and fuses with the sternum.
Ancient people thought the xiphoid looked like a sword and this is where it gets its name. The word xiphoid comes from the Greek word "xiphos" which meams straight sword, and the word "eidos" which means like.
The xiphoid process also known as the xiphisternum or metasternum is an extension of the lower part of the sternum. It is comprised of cartilage, is teardrop shaped, and has a small hole in it.
The xiphoid process anchors several muscles including the abdominal diaphragm, "a sheet-like muscle that is necessary for normal breathing". It also anchors the rectus abdominus muscle (the "abs," responsible for the bodybuilder's "sixpack") and the transversus thoracis muscle, located just inside the front of the ribs."
Caution should be taken during CPR as the xiphoid process can be easily broken and cause internal organ damage.