Bone marrow has got nothing to do with the spinal cord. Bone marrow used for transplants (hematopoietic marrow) has the appearance of normal blood and it is usually retrieved from the pelvic bones near the iliac crest. Bone marrow has the function of producing fresh blood cells (red blood cells, white blood cells and platelets) to substitute the ones that are normally removed from the blood stream. A red blood cell has an average life span of 120 days.
Hematopoiesis starts from a single cell line (hematopoietic stem cells, HSC) within the bone marrow. Bone marrow is localized in various segments of the skeletal system: ribs, sternum, hip bones, scapule, cranium and proximal extremities of humerus and femur.
In various blood diseases, like leukemia, bone marrow loses this function.