What is prime mover for arm flexion?
Actually its the Brachialis muscle that is the prime mover to flex the upper limb at the elbow. The biceps brachi (leymen: biceps) is only a helper and only when the arm is suppinated, suppination being the biceps primary function. Technically the arm is only the region of the upper limb between the shoulder and the elbo and thus flexion of the arm actually means lifting the humerus up and forwards.
