The portion of a long bone formed during secondary ossification, and initially separated from the diaphyses by cartilage. They ossify separately and eventually fuse with the diaphysis (see figure below).
Epiphysis and related parts of a long bone (viz., humerus).
See Adolescent growth spurt, Chrondrification, Diaphysis, Endochondral ossification, Joint capsule, Musculoskeletal system, Ossification