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What are the diaphysis, metaphysis, and epiphysis of a long bone?
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bone
A long bone of the human body, showing a magnified cross section of the interior.
Long bones, which are characteristic of the body’s extremities, are organized into three primary structural regions:
- Diaphysis: This is the central, tubular shaft of the bone. It is typically thick-walled and designed to support weight or act as a lever arm.1
- Metaphysis: Located between the diaphysis and the epiphysis, this region flares outward and possesses a predominantly cancellous internal structure. Its primary function is to transfer loads from weight-bearing joint surfaces to the diaphysis.1
- Epiphysis: This is the expanded end of a long bone. It consists of a cancellous internal structure covered by a thin layer of compact bone and forms the bony substructure of the joint.21
Prior to skeletal maturity, the epiphysis is separated from the metaphysis by a cartilaginous growth plate, which facilitates longitudinal bone growth. Once full growth is attained, this plate is replaced by bone, and the epiphysis becomes fixed to the shaft.213