Bone marrow of left femur
Medulla ossium
SkeletalSkeletonLegLeft side
- What it is
- Soft tissue filling the medullary cavity of the femoral shaft, revealed by peeling away the compact bone; in adults the shaft holds mostly fatty yellow marrow.
- Function
- Red marrow (in the ends of long bones, pelvis, sternum and vertebrae) makes about 500 billion blood cells a day; yellow marrow stores fat and can convert back when needed.
- Size
- Medullary cavity ≈ 15 mm across, ≈ 25 cm long
- Clinical note
- A large femoral fracture can release marrow fat into the bloodstream (fat embolism syndrome).