ANATOMY OF THE RIBS
The term “true” ribs refers to the vertebrosternal pairs of ribs numbered 1-7 and they are fixed ribs that do attach to the sternum. The term “false” ribs refers to the pairs of ribs numbered 8-12 that connect indirectly to the sternum by the costal cartilages of the ribs above them. These “false” ribs have the ability to move as the lungs expand and contract.
The rib pairs numbered 11-12 are called “floating “ ribs because they are attached only to the vertebrae, and not to the sternum or cartilages of the sternum. These ribs are small, delicate, and include a cartilaginous tip. The spaces between the ribs are called the intercostal spaces and within these spaces are the muscles, nerves, arteries, and veins.
The head of each rib has two facets on its’ surface; one is for articulation with the corresponding vertebra, and one is for articulation with the immediately superior vertebra. All ribs are attached in the back to the thoracic vertebrae.