Tendon sheath of extensor carpi ulnaris
Vagina tendinis extensoris ulnaris carpi
- Latin synonym: Vagina tendinis musculi extensoris carpi ulnaris
- Synonym: Tendinous sheath of extensor carpi ulnaris muscle
- Related terms: Tendinous sheath of extensor carpi ulnaris
Definition
The tendon sheath of extensor carpi ulnaris (ECU) encloses the ECU tendon as it passes through the sixth dorsal compartment of the wrist, just posterior to the ulnar styloid process. It lies within a fibro-osseous tunnel formed by the ulnar groove and the extensor retinaculum. The synovial sheath extends a few centimetres proximal to the ulnar styloid process and distally towards the base of the 5th metacarpal, allowing smooth, friction-free tendon movement during wrist extension and ulnar deviation.
Clinically, inflammation or tearing of this sheath can lead to ECU tenosynovitis or tendon subluxation, particularly in athletes performing repetitive wrist motions.
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).
