The flexor retinaculum (transverse carpal ligament or anterior annular ligament) is a fibrous band on the palmar side of the hand near the wrist. It arches over the

carpal bones The carpal bones are the eight small bones that make up the wrist (carpus) that connects the hand to the forearm. The terms "carpus" and "carpal" are derived from the Latin wikt:carpus#Latin, carpus and the Greek language, Greek wikt:καρπός ...

of the hands, covering them and forming the

carpal tunnel In the human body, the carpal tunnel or carpal canal is a flattened body cavity on the flexor ( palmar/volar) side of the wrist, bounded by the carpal bones and flexor retinaculum. It forms the passageway that transmits the median nerve and the ...

Structure

The flexor retinaculum is a strong, fibrous band that covers the carpal bones on the palmar side of the hand near the wrist. It attaches to the bones near the

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

and

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

. On the ulnar side, the flexor retinaculum attaches to the

pisiform bone The pisiform bone ( or ), also spelled pisiforme (from the Latin ''pisiformis'', pea-shaped), is a small knobbly, sesamoid bone that is found in the wrist. It forms the ulnar border of the carpal tunnel. Structure The pisiform is a sesamoid bone ...

and the hook of the hamate bone. On the radial side, it attaches to the tubercle of the

scaphoid bone The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid b ...

, and to the medial part of the palmar surface and the ridge of the trapezium bone. The flexor retinaculum is continuous with the

palmar carpal ligament The palmar carpal ligament (also volar carpal ligament or ''Guyon's Tunnel'') is a thickened portion of antebrachial fascia on anterior/palmar side of the wrist which - together with the flexor retinaculum of the hand - retains the tendons of most ...

, and deeper with the palmar aponeurosis. The

ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the Human Anatomical Terms#Anatomical directions, medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins ...

and

ulnar nerve The ulnar nerve is a nerve that runs near the ulna, one of the two long bones in the forearm. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or ...

, and the cutaneous branches of the median and

s, pass on top of the flexor retinaculum. On the radial side of the retinaculum is the tendon of the

flexor carpi radialis In anatomy, flexor carpi radialis is a muscle of the human forearm that acts to flex and (radially) abduct the hand. The Latin ''carpus'' means wrist; hence flexor carpi is a flexor of the wrist. Origin and insertion The flexor carpi radialis is ...

, which lies in the groove on the greater multangular between the attachments of the ligament to the bone. The tendons of the palmaris longus and

flexor carpi ulnaris The flexor carpi ulnaris (FCU) is a skeletal muscle, muscle of the forearm that flexion, flexes and Adduction, adducts at the wrist joint. Structure Origin The flexor carpi ulnaris has two heads; a humeral head and ulnar head. The humeral head o ...

are partly attached to the surface of the retinaculum; below, the short muscles of the thumb and

little finger The little finger or pinkie, also known as the baby finger, fifth digit, or pinky finger, is the most ulnar and smallest digit of the human hand, and next to the ring finger. Etymology The word "pinkie" is derived from the Dutch word ''pink' ...

originate from the flexor retinaculum.

Function

The flexor retinaculum is the roof of the

, through which the

median nerve The median nerve is a nerve in humans and other animals in the upper limb. It is one of the five main nerves originating from the brachial plexus. The median nerve originates from the lateral and medial cords of the brachial plexus, and has cont ...

and tendons of muscles which flex the hand pass.

Clinical significance

carpal tunnel syndrome Carpal tunnel syndrome (CTS) is a nerve compression syndrome associated with the collected signs and symptoms of Pathophysiology of nerve entrapment#Compression, compression of the median nerve at the carpal tunnel in the wrist. Carpal tunn ...

, one of the tendons or tissues in the carpal tunnel is inflamed, swollen, or fibrotic and puts pressure on the other structures in the tunnel, including the

. Carpal tunnel syndrome is the most commonly reported nerve entrapment syndrome. It is often associated with repetitive motions of the wrist and fingers. It is because of this that pianists, meat cutters, and people with jobs involving extensive typing are at particularly high risk. The tough flexor retinaculum along with the rest of the carpal tunnel cannot expand, putting pressure on the median nerve running through the carpal tunnel with the flexor tendons of the wrist. This results in the symptoms of carpal tunnel syndrome. Symptoms of carpal tunnel syndrome include tingling sensations and muscle weakness in the palm and lateral side of the hand and palm. It is possible that the syndrome may extend and radiate up the nerve causing pain to the arm and shoulder. Carpal tunnel syndrome may be treated surgically. This is usually done after all non-surgical methods of treatment have been exhausted. Non-surgical treatment methods include anti-inflammatory drugs. The wrist may be immobilized in order to prevent further use and inflammation. When surgery is needed, the flexor retinaculum is either completely severed or lengthened. Surgery to divide the flexor retinaculum is the most common procedure. The scar tissue will eventually fill the gap left by surgery. The intent is that this will lengthen the flexor retinaculum enough to accommodate inflamed or damaged tendons and reduce the effects of compression on the median nerve. In a 2004 double blind-study, researchers concluded that there was no perceivable benefit gained from lengthening the flexor retinaculum during surgery and so division of the ligament remains the preferred method of surgery.

References

External links

* * * {{Authority control Musculoskeletal system Hand Ligaments

Structure

Function

Clinical significance

See also

References

External links