Flexor Carpi Ulnaris Muscle

Original Editor Uchechukwu Chukwuemeka

Top Contributors - Uchechukwu Chukwuemeka, Ananya Bunglae Sudindar, Patti Cavaleri and Vidya Acharya

Original Editor -

Top Contributors - Uchechukwu Chukwuemeka, Ananya Bunglae Sudindar, Patti Cavaleri and Vidya Acharya

Description

Flexor carpi ulnaris muscle (FCU) is the most medial flexor muscle in the superficial compartment of the forearm. It can adduct and flex the wrist at the same time; acts in tandem with flexor carpi radialis to flex the wrist and with the extensor carpi ulnaris to adduct the wrist. This muscle is the only muscle in the anterior compartment that is fully innervated by the ulnar nerve.

Origin

It has a long linear origin from olecranon and posterior border of the ulna. In addition to that, FCU also has a humeral head origin from the medial epicondyle of the humerus.

Insertion

FCU inserts at the base of Pisiform bone, hook of hamate and base of 5th metacarpal.

Innervation

FCU is innervated by the Ulnar nerve (C7, C8, T1)

Blood supply

The FCU is supplied by the ulnar collateral arteries along with the anterior and posterior ulnar recurrent arteries.

Function

FCU flexes and adducts the hand at the wrist joint.

Clinical Relevance

• The ulnar nerve gains access to the forearm by passing between the humeral and ulnar heads of the FCU. Within the cubital tunnel, compression and entrapment of the ulnar nerve may manifest, occurring between the aponeuroses of the two heads of the FCU. This anatomical scenario underscores the clinical significance of potential issues associated with ulnar nerve compression in the cubital tunnel.
• The FCU tendon insertion serves as a landmark in finding the ulnar nerve and ulnar artery, which are lateral to the tendon at the wrist joint.
• FCU shares a common tendon with the other wrist flexors and can be involved in various pathologies associated to them such as medial epicondylalgia.
• The FCU, situated in the forearm, is susceptible to involvement in Volkmann's contracture. In Volkmann's contracture, ischemic damage compromises the FCU, along with other muscles, leading to fibrosis and contracture. This constriction can result in deformities and impaired function in the affected limb.

Assessment

Palpation

• The flexor carpi ulnaris can be palpated by locating the bony landmarks associated to the muscle. These include the medial epicondyle (origin), the olecranon process (to identify the ulna) and the pisiform bone (insertion).
• After identifying the bony landmarks, the person is asked to perform ulnar deviation and wrist flexion simultaneously, which will help locate the FCU muscle.

The video below demonstrates the palpation of the FCU muscle:

Manual Muscle Testing

• The patient/client is seated with the posterior aspect of the forearm and hand flat on a table.
• The therapist is seated at the side of the upper limb being tested. The therapist stabilizes the patient's forearm and palpates the muscle and its tendon. The other hand is placed on the radial side of the patient's hand at the 5th metacarpal and metacarpophalangeal joint of the patient.
• Instruction: The patient is instructed to perform ulnar deviation while flexing the wrist against the therapist's resistance.

The video below demonstrates manual muscle testing for FCU:

For further reading refer to Manual Muscle Testing: Wrist Flexion