Upper limb

Extensor Retinaculum (Wrist)

Retinaculum musculorum extensorum

Origin

Lateral border of the distal radius

Insertion

Medially at the pisiform, triquetrum, and periosteum of the distal ulna, with septa extending down to the underlying bone

Function

A broad fibrous band running transversely across the dorsal wrist that holds the extensor tendons of the wrist and fingers against the underlying bone during wrist movement (preventing 'bowstringing'); the septa divide the tendons into six separate synovial compartments, each with its own tendon sheath

Innervation

No independent (motor) innervation: it is passive connective tissue, not muscle; the overlying skin receives sensory supply from the radial nerve (superficial branch) and the ulnar nerve (dorsal branch)

Movement & chain

Holds the extensor tendons of the wrist and fingers close to the underlying bone during wrist dorsiflexion, preventing the tendons from springing away (bowstringing); a functional part of the chain enabling wrist and finger extension.

Palpation

Palpable as a tight, broad band over the dorsal wrist, most clearly felt with active wrist extension against resistance.

Clinical

Thickening/inflammation of the first compartment (abductor pollicis longus and extensor pollicis brevis muscles) causes De Quervain's disease; the retinaculum is also the landmark for surgical release of an extensor tendon stenosis and is sometimes used as graft material in tendon reconstructions.

Segmental innervation

The skin over the retinaculum receives sensory supply via segments C6-C8 (superficial branch of the radial nerve) and C8-T1 (dorsal branch of the ulnar nerve).

In clinical practice

Together with the underlying tendons, forms a landmark in physical examination of the dorsal wrist (e.g. the Finkelstein test for the first compartment) and in localizing a dorsal wrist block for regional anesthesia.

Region in the model

Upper limb