The biceps or biceps brachii ( Latin : musculus biceps
brachii , “two-headed muscle of the arm”) is a large muscle
that lies on the front of the upper arm between the shoulder
and the elbow. Both heads of the muscle 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 elbow where it flexes the forearm and supinates the
forearm. Both these movements are used when opening a
bottle with a corkscrew: first biceps screws in the cork
(supination), then it pulls the cork out (flexion