Annular Ligament of the Radius, Anterior View

Description

Across the anterior elbow, the annular ligament encircles the head of the radius as a fibrous ring, tethering it against the radial notch of the ulna while leaving the articular circumference free to rotate. Superiorly, the capitulum of the distal humerus forms the radiohumeral articulation with the radial head, with the ulnohumeral joint lying more medially at the trochlea and trochlear notch. The radial collateral ligament blends laterally with the annular ring, reinforcing the proximal radioulnar complex. Clear bony landmarks. That relationship matters because pronation and supination depend on the radial head spinning within the annular collar without subluxating anteriorly or laterally. Pediatric nursemaid’s elbow (radial head subluxation) occurs when longitudinal traction allows the radial head to slip partially from the annular ligament, often trapping the ligament between the radial head and capitulum and producing acute refusal to use the limb. Surgical reconstruction and post-traumatic instability assessments also reference this anatomy, since disruption of the annular ligament and lateral collateral complex can contribute to posterolateral rotatory instability patterns at the elbow. Educators will find this anterior perspective effective for teaching proximal radioulnar mechanics in upper limb anatomy and kinesiology courses, and for clarifying the ligamentous constraints emphasized in orthopedic and emergency medicine modules on radial head subluxation. Publishers can pair it with radiographs or ultrasound discussions of the radiohumeral joint to orient readers to the annular ring and adjacent collateral fibers. Anatomical accuracy verified by SciePro's Medical Advisory Board.