n. the small rounded end of a bone that articulates with another bone. For example, the capitulum humeri (or capitellum) is the round prominence at the elbow end of the humerus that articulates with the radius.
n. the bone of the upper arm (see illustration). The head of the humerus articulates with the *scapula at the shoulder joint. At the lower end of the shaft the trochlea articulates with the *ulna and part of the radius. The radius also articulates with a rounded protuberance (the capitulum) close to the trochlea. Depressions (fossae) at the front and back of the humerus accommodate the ulna and radius, respectively, when the arm is flexed or straightened.... humerus
n. death of bony tissue, usually adjacent to a joint surface where it is enclosed by avascular cartilage. It is usually caused by loss of blood supply (avascular necrosis) due to trauma and is a definitive feature in a variety of conditions, including *Legg-Calvé-Perthes disease, *sickle-cell disease, *Gaucher’s disease, epiphyseal infection and fractures, alcohol abuse, and high-dosage corticosteroids. Sites that are particularly susceptible include the head of the femur, the scaphoid and lunate bones of the wrist, the *capitulum of the humerus, and the talus and navicular bones of the ankle. In its earliest stages there is localized pain without any changes visible on X-ray examination; a *bone scan or MRI will assist with diagnosis.... osteonecrosis
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