In
human anatomy, the
biceps brachii , commonly known as the
biceps, is a two-headed
muscle that lies on the upper arm between the shoulder and the elbow. Both heads arise on the
scapula and join to form a single muscle belly which is attached to the upper forearm. While the biceps crosses both the
shoulder and elbow joints, its main function is at the latter where it flexes the forearm at the elbow and
supinates the forearm. Both these movements are used when opening a bottle with a corkscrew: first biceps unscrews the cork (supination), then it pulls the cork out (flexion).