Broken Bones and cell-phones

After fracture of the clavicle, the sternocleidomastoid muscle elevates the proximal fragment of the bone. The trapezius muscle is unable to hold up the distal fragment owing to the weight of the upper limb, and thus the shoulder drops. The adductor muscles of the arm, such as the pectoralis major, may pull the distal fragment medially causing the bone fragments to override.