Epiphysis
Also called: epiphyses
What it means
The epiphysis is the rounded end part of a long bone, found beyond the growth plate, that forms part of a joint.
The epiphysis forms the joint surfaces of your bones, so its health and the hormones that support it matter for lifelong joint and skeletal strength.
The epiphysis is the rounded end of a long bone, like the knobby ends of your femur (thigh bone) or humerus (upper arm bone). It sits beyond the growth plate and is covered with articular cartilage where it meets another bone to form a joint. In children and teens, the epiphysis is separated from the shaft by the growth plate, which closes once growth is complete.
Epiphyses matter in bone health discussions mostly because of how and when they fuse. Research on rare cases of men with impaired estrogen signaling has shown that these men can have unfused growth plates and low bone density even when testosterone levels are normal. This has helped researchers understand that estrogen, not just testosterone, plays an essential role in normal bone growth and growth plate closure in men, not only in women.
For adults, the epiphysis is no longer a 'growing' region, but it remains an important structural area, since it's where joints form and where fragility fractures (like hip fractures involving the femoral head, a type of epiphysis) often occur. Understanding its role helps explain why healthy sex hormone levels, in both men and women, support strong bone throughout life, not just during growth.
The epiphysis forms joint surfaces at the ends of long bones, shaping joint and skeletal strength for life.
Where this leads
WordThe epiphysis sits beyond the growth plate. Curious how that cartilage layer shaped your bone's final size before adulthood?
Where the Academy teaches it
This page is the short version. The lessons teach it in full, with the context around it and a quiz to lock it in.
Related words
A growth plate (epiphyseal plate, or physis) is a layer of cartilage near the ends of a child's or teen's long bones…
The diaphysis is the long middle shaft of a long bone, such as the femur or humerus, made mostly of dense cortical…
The metaphysis is the flared, wider section of a long bone located between its shaft and the rounded end near a…
The femoral head is the rounded, ball-shaped top of the thighbone (femur) that fits into the hip socket to form the…
The femur, or thigh bone, is the longest and strongest bone in the body, stretching from the hip to the knee and…
Estrogen is a hormone that protects bone by keeping bone-removing cells in check. Falling estrogen, especially at…
Education only, not medical advice. Decisions about tests, medications and treatment belong with your own doctor. OsteoStrong does not diagnose, treat or cure any disease.
