Bone marrow
Also called: red bone marrow
What it means
Bone marrow is the soft tissue inside bones where red bone marrow makes your red blood cells, white blood cells, and platelets.
Your bones protect the marrow that produces your blood cells every day, so bone health matters beyond just strength and fracture risk.
Bone marrow is the soft tissue inside your bones, and the red version is where your body makes blood. Every red blood cell, white blood cell, and platelet you have comes from red bone marrow — about 200 billion new blood cells every single day. The hard outer shell of cortical bone exists, in part, to protect this factory because it's so important and irreplaceable.
This shows that bone isn't just a structural frame for your body. It's also a living organ system that supports blood production, immunity, and more. When people talk about bone health, it's easy to think only about strength and fracture risk, but the marrow inside is doing essential work too.
Bone marrow can also be affected by disease. Multiple myeloma, for example, is a cancer of plasma cells that lives inside the marrow and disrupts the normal balance of bone building and breakdown, leading to bone destruction. This is a reminder that bone marrow health and skeletal health are closely connected, and any concerns about blood counts or bone pain are worth discussing with your doctor.
How sure is this?
Graded Established Science: Supported by broad scientific consensus and decades of research. Read each study with its grade in mind. One study is a piece of the picture, not the whole of it.
Bones protect marrow, which makes your blood cells every day, so bone health matters beyond strength alone.
Where this leads
WordIf bones protect marrow, you might wonder how bone itself stays strong. Here's the remove-and-rebuild cycle that keeps your skeleton going.
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.
Questions people ask about this
No — bones are far more than scaffolding. They're living, constantly rebuilding organs with their own blood supply and nerves, they bank your body's calcium and phosphorus, protect the bone marrow that makes your blood cells, and even release a hormone that talks to your pancreas, testes, and brain.
Read the full answer →Related words
Cortical bone is the dense, hard outer layer of bone that forms a protective shell and resists bending and twisting…
Trabecular bone is the spongy, honeycomb-like bone found inside structures like your spine and hip, providing…
Multiple myeloma is a cancer of plasma cells in the bone marrow that disrupts the normal bone rebuilding process,…
Bone remodeling is the lifelong cycle where cells called osteoclasts remove old bone and osteoblasts build new bone…
Osteoclasts are the cells that break down old bone tissue, working alongside bone-building osteoblasts to constantly…
The ilium is the largest, uppermost part of the pelvis—the wide, curved bone you feel as your hip bone.
The sternum, or breastbone, is the flat bone in the middle of your chest that connects to your ribs through…
The marrow cavity is the hollow, central space inside a long bone that holds bone marrow.
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.
