Yellow bone marrow
Also called: fatty marrow
What it means
Yellow bone marrow is the soft, fatty tissue found mostly in the hollow centers of long bones, as opposed to red marrow, which makes blood cells.
Knowing what fills your bone's hollow spaces helps you understand bone anatomy beyond just density numbers.
Bone marrow fills the hollow space inside your bones. There are two types: red marrow, which makes blood cells, and yellow bone marrow, which is mostly fat cells along with some connective tissue. Yellow marrow is stored mainly in the marrow cavity of long bones like the femur and humerus, in the shaft area rather than the ends.
As people age, some red marrow naturally converts to yellow marrow, since the body needs less active blood-cell production in certain bones over time. This is a normal part of aging and isn't itself a disease, though in some bone marrow or blood disorders the balance between red and yellow marrow can shift in ways doctors track with imaging.
Yellow marrow isn't directly involved in making new bone, but it shares space with the structures that do, like the endosteum lining the marrow cavity. Understanding marrow type can be useful context when a doctor reviews imaging of your bones, but it's a separate topic from bone density or fracture risk, which are measured differently.
Yellow bone marrow is the soft, fatty tissue filling the hollow centers of your long bones.
Where this leads
WordWondering what the other kind of marrow does? See how red marrow inside your bones produces blood cells every day.
Related words
Bone marrow is the soft tissue inside bones where red bone marrow makes your red blood cells, white blood cells, and…
The marrow cavity is the hollow, central space inside a long bone that holds bone marrow.
The endosteum is the thin layer of cells lining the inner surface of bone, next to the marrow cavity.
The diaphysis is the long middle shaft of a long bone, such as the femur or humerus, made mostly of dense cortical…
The femur, or thigh bone, is the longest and strongest bone in the body, stretching from the hip to the knee and…
The humerus is the long bone of the upper arm, stretching from the shoulder to the elbow.
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.
