Diaphysis
Also called: bone shaft
What it means
The diaphysis is the long middle shaft of a long bone, such as the femur or humerus, made mostly of dense cortical bone surrounding a hollow marrow cavity.
Knowing where the diaphysis is helps you understand fracture locations and bone anatomy terms used in imaging reports.
The diaphysis is the long, tube-shaped middle section of a long bone, like the femur (thigh bone) or humerus (upper arm bone). It's made mostly of dense cortical bone, which forms a sturdy outer wall surrounding a hollow space called the marrow cavity. This design gives long bones the strength to handle daily loads while staying relatively lightweight.
On each end, the diaphysis connects to the metaphysis and then the epiphysis, the rounded ends of the bone near joints. In children, growth plates between these sections allow the bone to lengthen; once growth is complete, the sections fuse together but the names for each region remain useful for describing bone anatomy and injuries.
Doctors and radiologists use the term diaphysis to pinpoint where a fracture or other bone problem is located, since shaft fractures behave differently than breaks near a joint. Knowing this basic anatomy can help you understand your own imaging reports or conversations with your doctor about bone health.
The diaphysis is the dense, hollow-cored shaft of long bones like the femur or humerus.
Where this leads
WordThe diaphysis surrounds a hollow marrow cavity. Discover what fills that central space and why its health matters for your bones.
Related words
The epiphysis is the rounded end part of a long bone, found beyond the growth plate, that forms part of a joint.
The metaphysis is the flared, wider section of a long bone located between its shaft and the rounded end near a…
Cortical bone is the dense, hard outer layer of bone that forms a protective shell and resists bending and twisting…
The marrow cavity is the hollow, central space inside a long bone that holds bone marrow.
The femoral shaft is the long middle part of the thighbone (femur), connecting the hip end to the knee end.
A long bone is a bone that's longer than it is wide, like the femur or humerus, with a shaft and two ends. These…
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