Extensor tendon compartments of the wrist are anatomical tunnels on the back of the

wrist In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; "The wrist contains eight bones, roughly aligned in two rows, known as the carp ...

that contain

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

s of muscles that extend (as opposed to flex) the wrist and the digits (fingers and thumb). The extensor tendons are held in place by the extensor retinaculum. As the tendons travel over the posterior (back) aspect of the wrist they are enclosed within synovial tendon sheaths. These sheaths reduce the friction to the extensor tendons as they traverse the compartments that are formed by the attachments of the extensor retinaculum to the distal (far end) of the

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

and

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

Structure

The compartments are numbered with each compartment containing specific extensor tendons.

Clinical significance

Any of the dorsal compartments of the wrist can develop

tenosynovial inflammation Tenosynovitis is the inflammation of the fluid-filled sheath (called the synovium) that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical manifest ...

. The first compartment is the most frequently affected site, called De Quervain's disease (syndrome or tenosynovitis). The other two most commonly injured are the sixth (extensor carpi ulnaris) and second (

intersection syndrome Intersection syndrome is a painful condition that affects the lateral side of the forearm when inflammation occurs at the intersection of the muscle bellies of the abductor pollicis longus and extensor pollicis brevis cross over the extensor carpi ...

) compartments. The first compartment is the site where entrapment tendinitis, better known as De Quervain's disease, occurs. Repetitive trauma is believed to cause thickening of the tendons, which lead to movement restriction of the tendons through the compartment. Any movement of the thumb and wrist causes the patient pain, inflammation and swelling. The presence of anomalous or variant muscles in the fourth compartment may result in chronic dorsal wrist pain, a condition known as the fourth compartment syndrome. Intersection syndrome can be caused by direct trauma to the second extensor compartment. It is however commonly brought on by activities that require repetitive wrist flexion and extension. Weightlifters, rowers, and other athletes are particularly prone to this condition. The patient presents with pain over dorsal aspect of the forearm and wrist. The tendon of 6th compartment (extensor carpi ulnaris) can suffer recurrent dislocation due to a tear of the ulnar side of the compartment. Those that engage in racket sports and golf seem to be at the highest risk for this condition.

Additional images

File:Gray421.png, Cross section of wrist showing six extensor compartments of hand

References

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