Wrist Extensor Compartments

compartimenta musculi extensoris carpi

The six extensor compartments are separated by fibrous septa from the extensor retinaculum, each with a specific anatomical relationship. From radial to ulnar: 1st (de Quervain's site), 2nd (second extensor compartment syndrome), 3rd (EPL around Lister's tubercle), 4th (most common extensor tenosynovitis zone), 5th (EDM, sagittal band pathology), 6th (ECU, subsheath tears).

Anatomical Data

Boundaries & Contents

Location	Back of the wrist, beneath the extensor retinaculum, over the distal radius and ulna
Boundaries	Floor: dorsal surfaces of the distal radius and ulna and the distal radioulnar joint capsule Roof: extensor retinaculum Walls: fibrous septa passing from the retinaculum to the bone, creating six separate tunnels
Contents	1st: abductor pollicis longus and extensor pollicis brevis 2nd: extensor carpi radialis longus and brevis 3rd: extensor pollicis longus 4th: extensor digitorum and extensor indicis 5th: extensor digiti minimi 6th: extensor carpi ulnaris

Biomechanics

Function & Actions

Keep the extensor tendons of the wrist, fingers and thumb in position as the wrist moves, each in its own synovial sheath.

Clinical Relevance

Clinical Notes

Intersection syndrome occurs at the crossing of the first and second compartment tendons 4-6 cm proximal to Lister's tubercle, the APL and EPB of the first compartment cross over the ECRL and ECRB of the second, producing friction tenosynovitis at the crossing point. Repetitive rowing, weight training, and cycling are common causes. Rest, splinting, and corticosteroid injection resolve most cases.

Pathology

Common Injuries & Conditions

Intersection Syndrome

First-second extensor compartment crossing tenosynovitis 4-6 cm proximal to Lister's tubercle producing dorsal forearm pain managed with rest, splint, and injection.

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