A 34 year old female was operated for fracture of the radial neck. Post-operatively she was unable to extend fingers at metacarpi-phalangeal joints. There was no sensory loss in the hand. Which nerve is most commonly injured?

Ans. B. Posterior interosseous nervePosterior interosseous nerve (PIN) is a branch of radial nerve. Below elbow, radial nerve divides into superficial radial nerve (Pure sensory) and posterior interosseous nerve (Pure motor). PIN is responsible for extension of fingers at Metacarpophalangeal joint and thumb. It is most commonly injured nerve in surgeries around radial head and neck.