A transparent kinematic model for exploring functional hand movement.

This is a rigid-link simulator, not an exact biological hand. Degrees of freedom describe independently variable movements; visible axes describe every rotation or translation shown in the mechanism.

Coupled mode links DIP flexion to PIP motion, thumb IP to MCP flexion, and fifth-metacarpal cupping to the ring side. Palm cupping rotates and translates the ring and little metacarpal bases to form a grasping hollow.