The ulnar collateral ligament of the elbow joint (UCL or internal lateral ligament) is a thick triangular band at the medial aspect of the elbow connecting the ulna to the humerus. It consists of two portions, an anterior and posterior, united by a thinner intermediate portion. Note that this ligament is also referred to as the medial collateral ligament and should not be confused with the lateral ulnar collateral ligament (LUCL).
The ulnar collateral ligament of the elbow joint is visible at center left.
Attachments and Course
The anterior portion, directed obliquely forward, is attached, above, by its apex, to the front part of the medial epicondyle of the humerus; and, below, by its broad base to the medial margin of the coronoid process of the ulna. The posterior portion, also of triangular form, is attached, above, by its apex, to the lower and back part of the medial epicondyle; below, to the medial margin of the olecranon. Between these two bands, a few intermediate fibers descend from the medial epicondyle to blend with a transverse band, which bridges across the notch between the olecranon and the coronoid process.
This ligament is in relation with the triceps brachii and flexor carpi ulnaris and the ulnar nerve, and gives origin to part of the flexor digitorum superficialis.