Definition

By: Gregory R. Waryasz, MD

The flexor carpi radialis muscle of the musculoskeletal system is characterized by being located just medial to the radial artery at the wrist.

It is part of the forearm.  It consists of skeletal muscle fibers.

Its unique structural features include its long fusiform shape that becomes tendinous at the mid-forearm. It is surrounded by a synovial sheath as it passes beneath the lateral flexor retinatculum and through vertical groove in the trapezium.

The common proximal attachment of all the superficial flexor-pronator muscles is the common flexor tendon to the medial epicondyle of the humerus.

The origin the medial epicondyle of the humerus.

The insertion is the base of the 2nd metacarpal.

The blood supply is from the ulnar artery and venous drainage is from the accompanying veins.

The innervation is from the median nerve.

The flexor carpi radialis muscle as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in the embryo.

The function of the flexor carpi radialis is to flex and abduct the hand at the wrist joint.  It works synergistically with the flexor carpi ulnaris.

Common diseases include tenosynovitis, tendon rupture, and medial epicondylitis.

Flexor carpi radialis tenosynovitisis a condition of pain with wrist motion due to inflammation of the tendon and tendon sheath.  Tenderness is common over the trapezium bone on the volar wrist.

Flexor carpi radialis tendon rupture can occur from a fall on an outstretched hand. It occurs at the insertion site at the base of the 2nd metacarpal and may be associated with an avulsion fracture.

Medial epocondylitis is a condition of pain and tenderness in the medial elbow at the site of the common flexor tendon origin.  It may begin as a microtear between the pronator teres and the flexor carpi radialis.  It may be associated with ulnar neuritis.

Commonly used diagnostic procedures include clinical history, physical exam, and MRI.

It is usually treated with physical therapy, a brace, and NSAIDs initially for medial epicondylitis and flexor carpi radialis tenosynovitis.  A corticosteroid injection may provide some relief.  Surgery may be helpful if physical therapy fails.   A ruptures tendon may or may not require surgery.

References

Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.

Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.

Wheeless’ Textbook of Orthopaedics: Flexor Carpi Radialis (http://www.wheelessonline.com/ortho/flexor_carpi_radialis)