Mallet finger is a flexion deformity of the distal phalanx, which occurs due to: (A) Avulsion fracture of middle phalanx, (B) Rupture of collateral slips of extensor expansion, (C) Rupture of central slip of extensor expansion, (D) Dislocation of distal interphalangeal joint
Answer is B. Mallet finger is a flexion deformity of the distal phalanx due to injury to the extensor digitorum at its inseion to the base of the distal phalanx (the collateral slips).