If spasms occur in the muscles surrounding the chest, back, and shoulders, they may cause the joints and other tissues in the area to shift, leading to the sternum popping or crackling.

Medically reviewed by Sanja Jelic, MD The diaphragm is a dome-shaped muscle that separates the chest from the abdomen. This ...

Costal cartilage anchors them to the edge of the sternum, or breastbone, in the middle of the chest at the front of the body. These ribs attach to the thoracic vertebra of the spinal column in the ...