Bone cortex
Also called: outer bone shell
What it means
The bone cortex is the hard, dense outer layer of bone that gives it strength and shape.
A thinner cortex can mean weaker bones, so keeping track of it helps show how much fracture protection your bones have.
Bone cortex is the dense, hard layer that wraps around every bone. It's made of cortical bone, a tightly packed material that gives bone its strength and shape. Under a microscope, it looks almost solid, unlike the lacy, open structure found deeper inside the bone.
Picture a bone like a tree trunk: the cortex is like the tough bark on the outside, while the spongy trabecular bone is like the softer wood inside. The cortex bears most of the mechanical load, especially in the shafts of long bones like the femur and humerus, which is why it's so thick there.
As we age, the cortex can gradually thin, and tiny channels inside it can widen, making it a bit weaker. This matters because bone scans and fracture-risk tools often look at how much cortex is left, especially at spots like the femoral neck or forearm, to understand overall bone strength.
The hard outer cortex gives bone strength, and a thinner cortex means weaker, more fracture-prone bones.
Where this leads
WordThe cortex is only the outer shell. Curious what's holding things up on the inside, especially in your spine and hip?
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…
The periosteum is the thin membrane that covers the outside of your bones, carrying blood vessels and nerves into…
The endosteum is the thin layer of cells lining the inner surface of bone, next to the marrow cavity.
A Haversian canal is a tiny tunnel running through dense bone that carries blood vessels and nerves to keep the bone…
Wolff's Law says your bones adapt to the loads you put on them, getting stronger with use and losing density when…
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.
