Final answer:
The dorsal interossei muscles at the MCP joints perform the action of abduction of the three middle fingers, aiding in both their abduction and flexion at these joints.
Step-by-step explanation:
The function of the dorsal interossei muscles at the metacarpophalangeal (MCP) joints is primarily abduction of the three middle fingers. Specifically, these muscles help in the abduction and flexion at the MCP joints while extending the fingers at the interphalangeal joints. Comprehending this mechanism is crucial for grasping the intricacies of hand movements and dexterity.
These muscles, situated within the hand, are intrinsic muscles and play a vital role in the fine motor control necessary for tasks involving the fingers. It is the biaxial nature of the MCP joints that allows for motions like flexion/extension as well as abduction/adduction, thus enabling these complex actions by the fingers coordinated by the dorsal interossei along with other intrinsic and extrinsic hand muscles.