Epiphysis

Each long bone has a proximal and a distal epiphysis (short bones of the hand have one). The epiphyses are broad to spread load over a large joint surface, and are filled with spongy bone containing red marrow, oriented to transmit forces from the articular surface to the shaft. Their articular surfaces are covered by hyaline articular cartilage, not periosteum.

Epiphyses ossify from secondary ossification centres, most of which appear after birth; growth in length occurs at the cartilaginous epiphyseal plate that separates epiphysis from metaphysis. Some bones also have apophyses — secondary centres that form non-articular bony prominences for tendon attachment (greater trochanter, tibial tuberosity, medial epicondyle), whose traction injuries cause apophysitis (Osgood–Schlatter, Sever).

The epiphyses of a long bone usually receive their own epiphyseal arteries; before plate fusion these are largely separate from the metaphyseal circulation, so damage can devascularise the epiphysis (e.g. slipped capital femoral epiphysis).