Supracondylar process of the humerus Supracondylar process of the humerus The supracondylar process of the humerus (also known as an "avian spur") is a bony projection on the anteromedial aspect of the upper arm bone (humerus), about 5 cm above the medial epicondyle. It is directed downward, forward and medially pointing to the medial epicondyle. It is an anatomical variation which occurs in about one percent of all people. A fibrous band, Struthers ligament, may connect this process to the medial epicondyle. Supracondylar processes are usually asymptomatic, but may be palpable as a mass on the upper arm. They are most commonly found as an
Bone marrow in the central skeleton, such as the pelvis, sternum, cranium, ribs, vertebrae and scapulae, and variably found in the proximal epiphyseal ends of long bones such as the femur and humerus. In circumstances of chronic hypoxia, the body can convert yellow marrow back to red marrow to increase blood cell production. At the cellular level, the main functional component of bone marrow includes the progenitor cells which are destined to mature into blood and lymphoid cells. Marrow contains hematopoietic stem cells which give rise to the three classes of blood cells that are found in circulation: white blood cells (leukocytes),