Medullary pin (1) for a distraction with segment transport and subsequent lengthening of a tubular bone, wherein the medullary pin (1) comprises: an at least partly hollow body (3) extending in an axial direction of the medullary pin (1), a locking means for locking the body (3) in a first end fragment (5) of the tubular bone, a first inner part (7), which is arranged displaceably in the axial direction inside the body (3) and comprises a first fixation means for the fixation of a middle fragment (15) of the tubular bone, a second inner part (17), which is arranged displaceably in the axial direction inside the body and comprises a second fixation means for the fixation of a second end fragment (25) of the tubular bone, and a drive unit (40) for the axial displacement of the first inner part (7) relative to the second inner part (17), wherein the drive unit (40) is arranged inside the body (3) between the first fixation means of the first inner part (7) and the second fixation means of the second inner part (17).