How many ribs are there including "floating" ribs? I am told by a CT scan report that my ribs 9,10, 11 and 12 are cracked but I do not see 12 ribs on the models shown.

This model has the entire rib cage which is 12 pairs. It may be hard to see by the photo as some of the ribs appear to overlay each other, but there are indeed 12 pairs.