* Flat bones: These include the sternum (breastbone), ribs, skull, scapulae (shoulder blades), pelvis, and hip bones.
* Long bones: These include the femur (thighbone), tibia (shinbone), fibula, humerus (upper arm bone), and radius and ulna (forearm bones).
While all bones produce bone marrow, the amount of red marrow (which is responsible for blood cell production) decreases with age. In adults, red marrow is primarily found in the flat bones and the ends of the long bones. The center of long bones usually contains yellow marrow, which is mostly fat.
