The annular ligament wraps around the radial head, holding it against the ulnar radial notch during forearm rotation. It is torn in pulled elbow (nursemaid's elbow) in children when the radial head is pulled through the ligament. Its constriction with scarring after radial head fracture can limit forearm rotation. The annular ligament contributes to lateral elbow stability alongside the LUCL.
| Origin | Anterior radial notch of the ulna |
|---|---|
| Insertion | Posterior radial notch of the ulna — forms a collar around the radial head |
| Actions | Maintains radial head in the radial notch during forearm rotation; transfers compressive loads from the radius to the ulna |
|---|
Nursemaid's elbow (pulled elbow) from sudden longitudinal traction on a child's arm (lifting them by the wrist) partially dislocates the radial head through the annular ligament. Reduction by supination with the elbow at 90 degrees immediately restores the radial head position and resolves the pain. No imaging required for the classic history.
Radial head subluxation through the annular ligament in children from traction force reduced by supination with the elbow at 90 degrees.
