( 1 ) Red marrow is found mainly in the flat bones , such as the hip bone , breast bone , skull , ribs , vertebrae and shoulder blades , and in the cancellous ( `` spongy '' ) material at the epiphyseal ends of the long bones such as the femur and humerus . Red marrow is found mainly in the flat bones , such as the hip bone , breast bone , skull , ribs , vertebrae and shoulder blades , and in the cancellous ( `` spongy '' ) material at the epiphyseal ends of the long bones such as the femur and humerus .