The flexor carpi ulnaris muscle (FCU) is a muscle of the human forearm that causes flexion and adduction of the hand. It arises by two heads from humerus and ulna connected together by a tendinous arch.
The humeral head arises from the medial epicondyle of the humerus by the common flexor tendon and ulnar head arises from the medial margin of the olecranon of the ulna and from the upper two-thirds of the dorsal border of the ulna.
It inserts into the pisiform bone and then via ligaments into the hamate bone and 5th metacarpal bone.
It is supplied by ulnar nerve.