Abductor Pollicis Longus Wrist Bursa

bursa tendinis musculi abductoris pollicis longi

The abductor pollicis longus tendon sheath is the synovial sleeve around the APL tendon in the first extensor compartment of the wrist, where it shares a tight tunnel over the radial styloid with extensor pollicis brevis. It lets the tendon glide under the extensor retinaculum, and thickening of this sheath is the basis of de Quervain tenosynovitis.

Anatomical Data

Boundaries & Contents

Location	Thumb side of the wrist, in the first extensor compartment over the radial styloid
Boundaries	Groove on the lateral distal radius at the radial styloid (floor) Extensor retinaculum over the first compartment (roof) A septum between APL and EPB in some people
Contents	Abductor pollicis longus tendon, often split into several slips

Biomechanics

Function & Actions

Lets the APL tendon glide in the tight first compartment. Inflammation and thickening here is de Quervain tenosynovitis.

Clinical Relevance

Clinical Notes

The APL wrist bursa is inflamed in de Quervain tenosynovitis alongside the EPB tendon sheath, both running in the first extensor compartment. Ultrasound demonstrates fluid in the first compartment sheath and associated bursal swelling. The Finkelstein test (ulnar deviation with thumb enclosed in fist) reproduces pain from bursal and tendinous compression under the retinaculum. First compartment release decompresses both the APL and EPB bursae simultaneously.

Pathology

Common Injuries & Conditions

De Quervain Tenosynovitis

Combined APL and EPB bursal and tendon sheath inflammation in the first extensor compartment producing radial wrist pain and thumb base tenderness, confirmed by positive Finkelstein test and treated by retinaculum release.

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