The trochlear notch (/ˈtrɒklɪər/),[1] also known as semilunar notch and 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.

About the middle of either side of this notch is an indentation, which contracts it somewhat, and indicates the junction of the olecranon and the coronoid process.

The notch is concave from above downward, and divided into a medial and a lateral portion by a smooth ridge running from the summit of the olecranon to the tip of the coronoid process.

This article incorporates text in the public domain from page 215 of the 20th edition of Gray's Anatomy (1918)

This human musculoskeletal system article is a stub.