Medial collateral ligament complex of the elbow

Last revised by Raymond Chieng on 26 Jun 2023

The medial (ulnar) collateral ligament (MCL/UCL) complex is a major stabilizer of the elbow joint and resists valgus stress.

The MCL complex runs from the humerus to the ulna and is composed of three parts 1,3,4,7:

  1. anterior bundle

    • inferior medial epicondyle to the sublime tubercle of the medial coronoid process

    • cord-like

  2. posterior bundle

    • medial epicondyle to the medial olecranon

    • thickening of the joint capsule

  3. transverse (or oblique) bundle (Cooper's ligament) 

    • runs between the inferior fibers of the anterior and posterior bundles (i.e. medial olecranon to medial coronoid process)

    • almost no role in elbow stabilization

  • accessory ligament (also known as extra band): posterior joint capsule to the transverse ligament (25%) 1

  • the anterior band is the only part of the MCL complex which is delineated as a separate structure and is best seen on coronal images

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Cases and figures

  • Figure 1: medial elbow ligaments (Gray's illustration)
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  • Figure 2: UCL tear illustrations
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  • Ulnar collateral ligament injury - elbow
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