Flexor Carpi Ulnaris – Anatomy, Nerve Supply, Function

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 4 min read
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Article Summary

Flexor Carpi Ulnaris is a fusiform muscle located in the anterior compartment of the forearm. It belongs to the superficial flexors of the forearm, along with pronator teres, palmaris longus, flexor digitorum superficialis and flexor carpi radialis. Flexor carpi ulnaris is the most medial of the superficial flexors. Together with other muscles of the anterior forearm, flexor carpi ulnaris flexes the hand at the wrist. Besides flexing the hand, flexor carpi ulnaris is also involved in the adduction of...

Key Takeaways

  • This article explains Structure in simple medical language.
  • This article explains Anatomy of Flexor Carpi Ulnaris in simple medical language.
  • This article explains Nerve supply of Flexor Carpi Ulnaris in simple medical language.
  • This article explains Blood Supply of Flexor Carpi Ulnaris in simple medical language.
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Definition

Flexor Carpi Ulnaris is a fusiform muscle located in the anterior compartment of the forearm. It belongs to the superficial flexors of the forearm, along with pronator teres, palmaris longus, flexor digitorum superficialis and flexor carpi radialis. Flexor carpi ulnaris is the most medial of the superficial flexors. Together with other muscles of the anterior forearm, flexor carpi ulnaris flexes the hand at the wrist. Besides flexing the hand, flexor carpi ulnaris is also involved in the adduction of the hand at the wrist.

Structure

Flexor carpi ulnaris muscle arises by two heads, humeral and ulnar, connected by a tendinous arch beneath which the ulnar nerve and  pass.

  • The humeral head arises from the medial epicondyle of the  by the common flexor .
  • The ulnar head arises from the medial margin of the olecranon of the  and from the upper two-thirds of the dorsal border of the ulna by an aponeurosis.

Its insertion is into the pisiform bone, into the hamate bone by the pisohamate  and into the fifth bone by the pisometacarpal ligament.

The muscle acts to flex and adduct the wrist joint.

of Flexor Carpi Ulnaris

Flexor carpi ulnaris
  • Origin: medial epicondyle of humerus via common flexor tendon and olecranon
  • Insertion: isoform, hook of hamate, 5th metacarpal
  • Action: flexion and adduction of the wrist
  • Innervation: ulnar nerve

Nerve supply of Flexor Carpi Ulnaris

The flexor carpi ulnaris muscle is innervated by the ulnar nerve that has its roots in the C8 and T1 spinal nerves.

Innervation of the flexor carpi ulnaris muscle is from the brachial plexus via the ulnar nerve (C7-T1).

Blood Supply of Flexor Carpi Ulnaris

Flexor carpi ulnaris receives its arterial blood supply via three different routes. Proximally, a branch of the posterior ulnar artery supplies the muscle as it passes between the humeral and ulnar heads. Branches of the ulnar artery supply the middle and distal parts of the muscle, with an accessory supply also present distally via the inferior ulnar collateral artery.

Tendon

The tendon of flexor carpi ulnaris can be seen on the anterior of the distal forearm. On a person’s distal forearm, just before the wrist, there are either two or three . The tendon of the flexor carpi ulnaris is the most medial (closest to the little finger) of these. The most lateral one is the tendon of flexor carpi radialis muscle, and the middle one, not always present, is the tendon of palmaris longus.

Function of Flexor Carpi Ulnaris

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. These exercises are used to prevent injury to the ulnar collateral ligament of elbow joint.

Due to its position and direction in the forearm, flexor carpi ulnaris can move the hand sideways as well as flexing it. Contracting with flexor carpi radialis and palmaris longus, flexor carpi ulnaris produces flexion of the hand at the wrist joint.

However, when it contracts alongside the extensor carpi ulnaris muscle in the posterior compartment, their counteracting forces produce adduction of the hand at the wrist, otherwise known as ulnar deviation or ulnar flexion.

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  2. Step 2

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  3. Step 3

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  4. Step 4

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