epiphyse

Epiphyse, in anatomy, refers to the end portion of a long bone. In English the term is epiphysis; in German it is Epiphyse. Each long bone typically has a proximal and a distal epiphysis that forms the joint surfaces with adjacent bones.

The epiphysis is separated from the shaft of the bone (the diaphysis) by the metaphysis during development. The growth plate, or epiphyseal plate, lies between the epiphysis and metaphysis and is the site of longitudinal bone growth in children and adolescents. In the growing skeleton, the plate consists of cartilage; with maturity, it ossifies to become an epiphyseal line.

Histologically, the epiphysis is mostly cancellous (spongy) bone interior, which contains red bone marrow. The outer surface may be covered by a thin layer of compact bone. The joint surface of the epiphysis is typically covered by articular cartilage, facilitating smooth articulation with adjacent bones.

Functionally, the epiphysis participates in weight bearing and articulation, distributing loads through the joint and contributing to bone lengthening during growth. Blood supply arises from separate metaphyseal and epiphyseal vessels that penetrate the region from surrounding soft tissues.

Clinical note: injuries affecting the epiphysis or growth plate can impact normal bone growth, especially in children. Fractures through the growth plate are classified by systems such as the Salter-Harris classification. In adults, the epiphysis can be involved in degenerative joint disease or traumatic injuries.