Tendon sheath of flexor carpi radialis
Vagina tendinis flexoris radialis carpi
- Latin synonym: Vagina tendinis musculi flexoris carpi radialis
- Synonym: Tendinous sheath of flexor carpi radialis muscle
- Related terms: Tendinous sheath of flexor carpi radialis
Definition
The tendon sheath of flexor carpi radialis is a synovial-lined tube (i.e. synovial sheath) that surrounds the tendon of the flexor carpi radialis (FCR) muscle as it passes across the wrist to insert on the base of the second (and sometimes third) metacarpal bone.
At the wrist, the FCR tendon runs through a fibro-osseous tunnel located lateral to the carpal tunnel. This tunnel is formed by:
An osseous floor, characterized by a groove located on the medial aspect of trapezium
A fibrous roof, created by the deep part of the flexor retinaculum that attaches to the margins of the groove on the medial surface of trapezium
Parietal and visceral layers of tendon sheath of flexor carpi radialis
Inside the fibro-osseous tunnel, the FCR tendon is surrounded by its own synovial sheath, separate from the carpal tunnel contents. Similar to other tendon sheaths, the tendon sheath of flexor carpi radialis also has two layers:
The parietal layer lines the inside of the trapezial tunnel and the deep surface of the flexor retinaculum.
The visceral layer closely invests the FCR tendon itself.
The small synovial space between these layers allows the tendon to glide smoothly as it flexes and abducts the wrist.
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.
Mehta, P., Thoppil, J., Koyfman, A. and Long, B., 2024. High risk and low prevalence diseases: Flexor tenosynovitis. The American Journal of Emergency Medicine, 77, pp.132-138.
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.
