Flexor carpi ulnaris muscle arises by two heads - humeral and ulnar, connected by a tendinous arch beneath which the ulnar nerve and ulnar artery pass.
The humeral head arises from the medial epicondyle of the humerus by the common flexor tendon.
The 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 by an aponeurosis.
Its insertion is into the pisiform bone and then via ligaments into the hamate bone and 5th metacarpal bone, acting to flex and adduct the wrist joint.
The tendon of flexor carpi ulnaris can be seen on the anterior of the distal forearm. On a person's distal forearm, right before the wrist, they will see either two or three tendons. Flexor carpi ulnaris is the most medial (closest to the little finger) of these. (The most lateral one is flexor carpi radialis muscle, and the middle one, if it exists, is palmaris longus.)
The muscle, like all flexors of the forearm, can be strengthened by exercises that resist its flexion. A wrist roller can be used and wrist curls with dumbbells can also be performed.