Which joint primarily facilitates finger flexion and extension?

The metacarpophalangeal joint serves as the primary joint responsible for flexion and extension of the fingers. Located at the base of each finger, it acts as a hinge joint, allowing for a wide range of motion necessary for grasping and manipulating objects. When the fingers bend (flex) or straighten (extend), it is primarily through the movement generated at this joint.

This joint connects the metacarpal bones of the hand to the proximal phalanges of the fingers. While other joints also facilitate movement, the metacarpophalangeal joint plays a critical role in overall finger function due to its location and the substantial range of motion it provides. The thumb, while functioning slightly differently, also utilizes this joint structure for its movements.

In summary, the metacarpophalangeal joint's pivotal role in allowing flexion and extension of the fingers makes it the correct choice.