Why yellow bone marrow is found in medullary cavity of only long bones...
At birth, all bone cavities contain only red marrow: no yellow marrow is present. Red marrow is converted into yellow marrow throughout an individual's life but is still the primary marrow present in children, residing in the medullary cavity of long bones, such as the femur. By adulthood, roughly equal amounts of yellow and red marrow exist, with flat bones, such as the pelvic girdle and sternum, containing the highest amounts of red marrow.
Why yellow bone marrow is found in medullary cavity of only long bones...
The yellow bone marrow is found especially in medullary cavity of long bones. White red bone marrow is found in spongy bones. In adults, red bone marrow is primarily found in the flat bones, such as the pelvic girdle and the sternum. In children, it is found in the medullary cavity of the longbones, such as the femur.