Epiphysis

The epiphysis (plural: epiphyses) is the rounded end of a long bone, at its joint with adjacent bone(s). It's distinct from the diaphysis, the long, narrow shaft of the bone. During skeletal development, the epiphysis is initially separated from the diaphysis by a layer of cartilage called the epiphyseal plate (or growth plate).

The primary function of the epiphysis is articulation with other bones, allowing for joint movement. The articular surface of the epiphysis is covered with a layer of hyaline cartilage, which provides a smooth, low-friction surface for joint movement and helps to protect the underlying bone from wear and tear.

The epiphysis also contributes to bone growth. The epiphyseal plate is the site of longitudinal bone growth. Cartilage cells within the epiphyseal plate proliferate and are replaced by bone tissue. This process continues until the end of puberty, at which point the epiphyseal plate ossifies and fuses with the diaphysis, forming the epiphyseal line, which indicates that bone growth has ceased.

Blood vessels supply the epiphysis, providing nutrients and oxygen for bone cell metabolism and growth. The epiphysis is also innervated, allowing for sensation and pain perception in the joint.

Damage to the epiphysis or epiphyseal plate during childhood or adolescence can disrupt normal bone growth, potentially leading to limb length discrepancies or deformities.