Extensor Pollicis Brevis Wrist Bursa

bursa tendinis musculi extensoris pollicis brevis

The extensor pollicis brevis tendon sheath is the synovial sleeve around the EPB tendon in the first extensor compartment of the wrist, alongside abductor pollicis longus. In some people a septum gives EPB its own subcompartment, which matters in de Quervain tenosynovitis because it can be missed at injection or surgery.

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	Extensor pollicis brevis tendon

Biomechanics

Function & Actions

Lets the EPB tendon glide beside APL. When a septum gives EPB its own subcompartment, de Quervain tenosynovitis may persist if that subcompartment is not released at surgery.

Clinical Relevance

Clinical Notes

The EPB bursa is co-inflamed with the APL bursa in de Quervain tenosynovitis. A separate sub-compartment for EPB within the first extensor compartment occurs in 25-30% of individuals and is the most common cause of failed de Quervain surgery when the EPB sub-compartment is not individually released.

Pathology

Common Injuries & Conditions

EPB Sub-compartment Syndrome

Failure of de Quervain surgery from an unrecognised separate EPB sub-compartment within the first extensor compartment, requiring revision surgery to release the EPB tunnel individually.

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