The term “floating rib” is used to refer to a specific anatomical structure and to a disorder which could better be termed a “slipped rib.” Both, as one might imagine from the name, involve the ribs, curved bones found in vertebrates. The ribs are attached to the spine and a structure called the sternum, creating the rib cage, a protective casing for vital organs such as the heart and lungs.
In the case of an anatomical structure, a floating rib is a rib which is attached to the spine, but not the sternum. Most people have floating ribs, with the 11th and 12th pairs of ribs being floating ribs. In some people, there are three pairs instead of two, and other individuals only develop one set of floating ribs. Floating ribs are entirely normal and nothing to be concerned about, and although they are not attached to the sternum, they aren’t exactly floating around in the body cavity; numerous attachments usually keep the floating ribs more or less in place.