Anatomy, Shoulder and Upper Limb, Elbow Annular Ligament

Excerpt

The annular ligament is located within the elbow joint. The elbow joint is comprised of three bones that form three articulations which are all contained within the elbow joint capsule. The humerus, radius, and ulna interact in a complex, dynamic relationship to constitute three distinct joint articulations:

1. Ulnohumeral articulation

2. 1. Distal humerus (trochlea) and the proximal ulna (trochlear notch, or greater sigmoid notch)

3. Radiocapitellar articulation

4. 1. Distal humerus (capitellum) and the proximal radius (radial head)

5. Proximal radioulnar articulation

6. 1. The proximal ulna (radial notch, or lesser sigmoid notch) and the proximal radius (radial head)

The elbow joint is both a uniaxial, hinge joint (ulnohumeral articulation) and a pivot joint (radiocapitellar articulation). The ligaments surrounding the elbow joint connect one bone to another and provide static stability while allowing the motion to occur. The annular ligament is a critical component of the lateral collateral ligament (LCL) complex. While the major roles of the ulnar collateral ligament (UCL) and the LCL complex include primary support against excessive valgus stress and varus stress, respectively, the annular ligament plays an additionally important role as a primary stabilizing structure for the radial head articulation with the radial notch of the proximal ulna during forearm supination and pronation.