Lateral ulnar collateral ligament

The lateral ulnar collateral ligament (LUCL) of the elbow is a part of the lateral collateral ligament complex of the elbow. It originates at the lateral epicondyle of the humerus and partially blends in with the annular ligament as it travels distally to insert on the supinator crest of the ulna.

The lateral ulnar collateral ligament (LUCL) is considered to be the primary stabilizer of the elbow joint against posterolateral rotatory instability. It prevents the ulna from rotating around its long axis away from the trochlea and stabilizes all three articulations of the elbow and contributes to the resistance of the rotatory forces of varus and external rotation. 

The lateral ulnar collateral ligament (LUCL) should not be confused with the “Ulnar collateral ligament of elbow” listed in the Terminologia Anatomica, and that corresponds to the medial collateral ligament complex of the elbow.