Upper limb

Flexor Carpi Ulnaris, Ulnar Head

Musculus flexor carpi ulnaris, caput ulnare

Origin

Olecranon and the posterior border of the ulna

Insertion

Pisiform bone (and via ligaments further to the hamate bone and the fifth metacarpal bone)

Function

Flexion and ulnar deviation of the wrist

Innervation

Ulnar nerve (C8–T1)

Movement & chain

Together with the humeral head forms flexor carpi ulnaris; does not itself border the carpal tunnel on the ulnar side, but the tendon lies right next to Guyon's canal.

Palpation

Easily palpated as the most ulnar wrist tendon on the anterior side, inserting on the pisiform bone, during resisted flexion with ulnar deviation.

Clinical

The ulnar nerve runs just behind the medial epicondyle between the two heads of this muscle (cubital tunnel) and can become entrapped here (cubital tunnel syndrome).

Segmental innervation

C8–T1.

In clinical practice

The pisiform bone and the FCU tendon form a landmark for locating Guyon's canal for the ulnar nerve.

Region in the model

Upper limb