Tendon sheath of extensors carpi radialis
Vagina tendinum extensorum radialium carpi
- Latin synonym: Vagina tendinum musculorum extensorum carpi radialium
- Synonym: Tendinous sheath of extensor carpi radialis muscles
- Related terms: Tendinous sheath of extensores carpi radiales
Definition
The tendons of extensor carpi radialis longus and brevis are enclosed in separate synovial sheaths as they descend through the second dorsal compartment of the wrist, lying beneath the extensor retinaculum. They course along the posterior surface of the styloid process of radius, positioned between the tendons of abductor pollicis longus and extensor pollicis brevis laterally (first compartment) and extensor pollicis longus medially (third compartment).
The tendon sheaths extend from just proximal to the wrist joint to the bases of the second and third metacarpal bones, where the tendons insert. These sheaths enable the tendons to glide smoothly over the dorsal surface of the radius, reducing friction during wrist extension and radial deviation.
Please note that the extensor retinaculum sends fibrous septa to the radius and ulna, dividing the dorsal wrist into six fibro-osseous compartments, each containing specific extensor tendons invested in their own synovial sheaths. The extensor carpi radialis longus and brevis tendons occupy the second dorsal compartment, immediately lateral to the tendon of extensor pollicis longus.
References
Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 50: Wrist and hand, pp. 879.
Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 7: Hand’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp. 757; Fig. 7.95.
MickeyMed. (n.d.). Extensor retinaculum of hand. Available at: https://www.mickeymed.com/article/extensorretinaculumofhand (Accessed: 7 January 2026).
