The ulnar collateral ligament (UCL or internal lateral ligament) is a thick triangular band at the medial aspect of the elbow uniting the distal aspect of the humerus to the proximal aspect of the ulna. 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).