What is a supernumerary bone?

Answer 1

"Accessory (supernumerary) bones develop when additional ossification centers appear and form extra bones. Many bones develop from several centers of ossification, and the separate parts normally fuse. Sometimes one of these centers fails to fuse with the main bone, giving the appearance of an extra bone; but careful study shows that the apparent extra bone is a missing part of the main bone. Circumscribed areas of bone are often seen along the sutures of the cranium where the flat bones abut, particularly those related to the parietal bone. These small, irregular, worm-like bones are sutural bones. It is important to know that accessory bones are common in the foot, to avoid mistaking them for bone fragments in radiographs and other medical images". Moore & Dalley. Clinical Oriented Anatomy. 5th edition. pg 21.

Answer 2

A supernumerary bone is an extra bone that may develop in a person's body in addition to the regular bones. These additional bones can occur in various parts of the body, such as the hands, feet, or spine, and can sometimes cause issues with movement or function. Supernumerary bones are rare and their presence may require medical evaluation and treatment.