Tendon sheaths of digits of hand
Vaginae tendinum digitorum manus
Definition
The tendon sheaths of digits of hand include the fibrous flexor sheaths and the synovial flexor sheaths.
1. Fibrous flexor sheaths
These are strong, tube-like structures attached to the phalanges and joint capsules along the palm side of each finger. They are made up of annular (A1–A5) and cruciform (C1–C3) pulleys, which together form a tough tunnel that keeps the flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP), and flexor pollicis longus (FPL) tendons close to the bone. Their main job is to prevent the tendons from bowstringing and to guide smooth, controlled movement during finger flexion.
2. Synovial flexor sheaths
These are thin, double-layered sacs inside the fibrous sheath that wrap around the long flexor tendons of the fingers. They produce a small amount of fluid that reduces friction and lets the tendons glide smoothly as the fingers move. In the hand, the synovial sheaths of the thumb and little finger are continuous with the radial and ulnar bursae, allowing the tendons to move freely across the palm.
Function
Together, they work to protect the long flexor tendons and allow smooth, friction-free movement during finger flexion and extension.
References
Hauger, O., Chung, C.B., Lektrakul, N., Botte, M.J., Trudell, D., Boutin, R.D. and Resnick, D., 2000. Pulley system in the fingers: normal anatomy and simulated lesions in cadavers at MR imaging, CT, and US with and without contrast material distention of the tendon sheath. Radiology, 217(1), pp.201-212.
Schmitt, R., Hesse, N. and Grunz, J.P., 2022, December. Tendons and tendon sheaths of the hand–an update on MRI. In RöFo-Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren (Vol. 194, No. 12, pp. 1307-1321). Georg Thieme Verlag KG.
