A bennett's fracture is difficult to maintain in reduced position because of the pull of?

Bennett's fracture is the paial aicular fracture of 1st metacarpal base extending into CMC joint and is unstable, in which small volar-radial fragment of metacarpal aicular surface remains attached to the anterior oblique ligament, while the remainder of the metacarpal aicular surface and shaft is displaced proximally, radially and into adduction in response to the force of the adductor pollicis and abductor pollicis longus. Ref: Apley's 8/e, Page 631-32; Watson Jones: fracture & Joint injuries 6/e, Page 760-62; Rockwood & Green's Fracture in Adults 6/e, Page 836-42.