Trochlear notch
（重定向自Semilunar notch）
The trochlear notch (also semilunar notch, or greater sigmoid cavity) is a large depression in the upper extremity of the ulna that fits the trochlea of the humerus (the bone directly above the ulna in the arm) as part of the elbow joint. It is formed by the olecranon and the coronoid process.