Upper limb
Tendon sheath of second extensor compartment (ECRL and ECRB)
Vagina tendinum musculorum extensorum carpi radialium
- Origin
- Second osteofibrous dorsal compartment on the dorsolateral distal radius under extensor retinaculum
- Insertion
- Sheaths the extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) tendons to the 2nd and 3rd metacarpal bases
- Function
- Enables smooth excursion of the primary wrist extensors across the radiocarpal joint
- Innervation
- Posterior interosseous nerve (C6–C7)
- Movement & chain
- Subject to high tensile friction during repetitive wrist extension and power gripping
- Palpation
- Palpable on the dorsoradial aspect of the distal radius just radial to Lister's tubercle
- Clinical
- Intersection syndrome (friction tendinitis approximately 4-6 cm proximal to the wrist where APL/EPB bellies cross over the ECRL/ECRB sheath in rowers, weightlifters, and racquet athletes)
- Segmental innervation
- C6–C7 spinal levels
- In clinical practice
- Managed with cock-up wrist splinting, activity modification, ice application, and targeted tendon loading protocols
- Region in the model
- Upper limb