The xiphoid process is the lowermost portion of the sternum, or breastbone. It is the small, tapered piece of bone that projects downward from the point where the two sides of the ribcage meet in the middle. Since it is so exposed, this bone is susceptible to fractures, in which it breaks off from the body of the sternum. Damage can be caused by any blunt trauma, such as a blow to the chest as occurs during contact sports or in a vehicle accident, or during cardiopulmonary resuscitation (CPR), when the caregiver uses improper technique when delivering chest compressions.
Situated in the very center of the chest, the xiphoid process can be located shortly below the nipple line in the space where the bottommost ribs meet. As it descends a short distance into this middle space and therefore is unprotected by the rib cage, and also because it lies so close to the skin, a blow to the chest can easily damage the process or break it off all together. The latter injury is considered very dangerous, not because of this bone’s function — it serves as an attachment site for the diaphragm muscle and for the rectus abdominus muscle in the abdomen — but because the broken piece of bone can easily puncture the heart, which lies immediately behind the sternum.
Blunt trauma is the most common cause of damage to the bone, with contact sports a frequent arena in which this injury is seen. In American football, for instance, the bone can be damaged when a player drives his helmet into another player’s chest. Rugby and boxing are two other sports in which athletes may apply direct blows to each other’s chests. Other causes of bodily trauma that may damage it include car accidents in which the body is thrown into the steering column, or being struck in the chest with a blunt object, such as a baseball pitcher being hit with the ball.
Another activity with a high risk of damage to the xiphoid process is CPR. Kneeling on the floor alongside an unconscious person who is lying face-up, the rescuer places the heel of his hands, on atop the other, on the middle of the chest at the nipple line and rapidly presses down and up on the sternum in hopes of pumping the heart muscle behind it. If the rescuer places the heels of his hands too low, he risks snapping off the bone during the delivery of compressions and therefore endangering the heart even more.