The occurrence of supernumerary ribs in the cervical or lumbar regions is not rare.1 On the other hand, congenital absence of ribs seldom occurs,2 although a few cases have been reported.3
The ribs may vary considerably in form and size, and Hrdlička,4 who has examined the ribs of several hundred skeletons, concludes that such variations occur much more frequently in the upper ribs.
Few instances of fusion of ribs have been reported. Meyer5 describes a patient in whom the second and third ribs were fused throughout three fourths of their length, and he refers to a report made by Lane in 1883, in which he recited several instances of fusion of a cervical and a first rib, and fusion of the first and second ribs. He also quotes Bland Sutton as authority for the statement that "fusion of the ribs, resulting in the formation of
Hatch HS, Plume CA. CONGENITAL MALFORMATION OF THE RIBS: REPORT OF AN EXTREME CASE. JAMA. 1932;99(15):1254. doi:10.1001/jama.1932.27410670003012c