A fracture in the shaft of a bone would be a breaking the diaphysis.(dia- through, physis=growth). Diaphysis or shafts forms the long axis of the bone.
Diaphysis is the main or mid section of a long bone. It is made up of the cortical bone and usually contains bone marrow and adipose tissue. It is a middle tubular part composed of compact bone which surrounds a central marrow cavity which contains red or yellow marrow.
