together w/ proximal portion of the coronoid process, olecranon forms greater sigmoid notch of the ulna, a deep depression that serves as articulation w/ trochlea that serves as the articulation w/ trochlea which allows motion only in anteroposterior plane and provides stability to the elbow joint;
articular cartilage surface is interrupted by a transverse line of bone, "bare area" located midway between tip of olecranon & coronoid process;
if this is not recongnized during reconstruction of frxed olecranon, there is temptation to eliminate any area uncovered by cartilage