Tendon sheaths

Tendon sheaths are specialized structures that surround tendons, particularly in areas where tendons pass over joints or through tight spaces. These sheaths serve several critical functions, including reducing friction, providing a smooth gliding surface, and protecting the tendon from mechanical stress and injury.

Tendon sheaths are composed of two main layers: an outer fibrous layer and an inner synovial layer. The outer fibrous layer provides structural support, while the inner synovial layer produces synovial fluid, which lubricates the tendon and facilitates its movement within the sheath.[1-2] This synovial fluid is essential for minimizing friction and wear on the tendon as it moves.

The anatomy of tendon sheaths can vary depending on their location and the specific tendons they encase. For example, the flexor tendon sheaths in the fingers are complex structures that include both fibrous and membranous components, which are crucial for the efficient function of the tendons during finger movements.[3]