Extensor retinaculum

The band of thick fibrous tissue across the back of the wrist that holds the extensor tendons against the bones and divides them into six compartments. The part over the first compartment forms the roof of the tunnel that thickens in De Quervain's tenosynovitis and is opened at its surgical release.

Related terms

• Anatomy

  First extensor compartment

  The fibro-osseous tunnel over the radial styloid through which the abductor pollicis longus and extensor pollicis brevis tendons pass under the extensor retinaculum. A septum divides it fully or partly in many wrists, more often in people with De Quervain's tenosynovitis, and the abductor pollicis longus often has several slips — both relevant to injection and to surgical release.

• Condition

  De Quervain's tenosynovitis

  Painful thickening of the first extensor compartment at the wrist, so that the abductor pollicis longus and extensor pollicis brevis tendons no longer glide freely. It causes pain over the thumb side of the wrist on gripping and pinching, is commoner in women, after 40 and around pregnancy, and is treated with a splint, a steroid injection or, if these fail, surgical release.

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