Ribs
There are usually 12 ribs on each side of the body They are elongated yet flattened bones that curve inferior and anterior from the thoracic vertebrae. The ribs, as well as the costal cartilages, increase in length from the first to the seventh, and their obliquity increases from the first to the ninth. Generally, ribs 1 to 7 are connected to the sternum' by their costal cartilages and are called true ribs, whereas ribs 8 to 12 are termed false ribs. Usually, ribs 8 to 10, by means of their costal cartilages, join the costal cartilage immediately above, whereas ribs 11 and 12, which are free, are known as floating ribs. A supernumerary rib may be found in either the cervical or lumbar region. In thoracic surgery, a portion of a rib can be excised, leaving its periosteum, which later allows regeneration of the bone.
