A study of the flexor digitorium superficialis tendon in flexion and extension at the proximal interphalangeal joint.

Using a physical model to represent the detailed morphology of the flexor digitorium superficial tendon, the functions of the fibrous arrangement of this tendon in the human fingers were studied for flexion and extension of the proximal interphalangeal joint. In extension of the joint, the fibrous pattern acted as a dynamic ligament for the joint. In flexion, the arrangement of fiber bundles of the tendon contributed to the balanced distribution of forces across the joint's surfaces and for mechanical interplay with the deep long flexor tendon in the region of the joint.