Bone marrow Bone marrow Bone marrow is a semi-solid tissue which may be found within the spongy or cancellous portions of bones. In birds and mammals, bone marrow is the primary site of new blood cell production or hematopoiesis. It is composed of hematopoietic cells, marrow adipose tissue, and supportive stromal cells. In adult humans, bone marrow is primarily located in the ribs, vertebrae, sternum, and bones of the pelvis. On average, bone marrow constitutes 4% of the total body mass of humans; in an adult having 65 kilograms of mass (143 lb), bone marrow typically accounts for approximately . Human marrow
Sacrum the direction of rotation of the superior portion of the sacrum opposite the side of the superior axis pole, and the last letter pertains to the pole. English "sacrum" was introduced as a technical term in anatomy in the mid-18th century, as a shortening of the Late Latin name "os sacrum" "sacred bone", itself a translation of Greek ἱερόν ὀστέον, the term found in the writings of Galen. Prior to the adoption of "sacrum", the bone was also called "holy bone" in English, paralleling German "heiliges Bein" or "Heiligenbein" (alongside "Kreuzbein") and Dutch "heiligbeen". The origin of Galen's term is