Summary Flexor Carpi Ulnaris Origin Humeral head: medial epicondyle of humerus; Ulnar head: olecranon and posterior border of ulna Insertion Pisiform bone, hook of hamate bone, and 5th metacarpal bone Action Flexes and adducts hand (at wrist) Innervation Ulnar nerve (C7, C8) Arterial supply Ulnar artery