Where is bone marrow found within the body?

At birth, all bone marrow is red. With age, more and more of it is converted to the yellow type. About half of adult bone marrow is red. Red marrow is found mainly in the flat bones, such as the hip bone, breast bone, skull, ribs, vertebrae and shoulder blades, and in the cancellous ("spongy") material at the epiphyseal ends of the long bones such as the femur and humerus. Yellow marrow is found in the hollow interior of the middle portion of long bones.