Determine how muscle forces map to attachment-point forces in the finger extensor mechanism

Determine the contributions of forces generated by the extrinsic extensor digitorum communis muscle and the intrinsic radial interosseous, ulnar interosseous, and lumbrical muscles to the forces transmitted by the finger extensor mechanism at its two principal attachments: the medial tendon at the base of the middle phalanx and the terminal tendon at the base of the distal phalanx.

Background

The extensor mechanism transmits forces from multiple muscles to attachments on the middle and distal phalanges via an interconnected network of collagen fiber bundles. Despite extensive modeling and anatomical descriptions, the precise mapping from individual muscle forces to the resulting forces at the medial and terminal tendinous attachments remains incompletely characterized.

This paper proposes a fiber-bundle-based numerical model including intercrossing fiber bundles and an extensor hood to investigate posture-dependent force transmission, highlighting the need for a clear quantitative relationship between muscle inputs and attachment-point outputs.