A 2-year-old child is lifted by one arm and then refuses to use the limb, holding it slightly flexed and pronated. Radiographs are normal. The injury involves which structure?
- A Interosseous membrane of the forearm
- B Ulnar collateral ligament of the elbow
- C Annular ligament, allowing subluxation of the radial head ✓
- D Tendon of triceps brachii at its olecranon insertion
Correct answer: C. Annular ligament, allowing subluxation of the radial head
Explanation
Pulled elbow (nursemaid's elbow) is traction-induced subluxation of the radial head through the annular ligament, which is lax and funnel-shaped in young children. Reduction is by supination and flexion. The ulnar collateral ligament resists valgus stress and is injured in throwing athletes, not toddlers, which eliminates option B.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.