How do your arm muscles work to lift a mug of coffee to your lips

Attaching to the wrist and elbow, the forearm supinates, or rolls palm forward. In this position, in which you could hold a bowl of soup, the forearm requires assistance from the biceps in order to lift the bowl to your mouth. Without the pulley action of the biceps, the forearm and wrist would lack sufficient flexibility to allow you to feed yourself, dress, brush your teeth or arm wrestle. The biceps brachii flexes the supinated forearm at the elbow.
 The distal end of the muscle, attaches to the radius, the bone in the forearm on the thumb side of the arm.