Final answer:
Flexing the metacarpophalangeal joints involves bending the fingers towards the palm, enabled by biaxial joints that permit a variety of hand movements. These joints are formed by the metacarpal bones of the hand and the proximal phalanges of the fingers.
Step-by-step explanation:
Flexing the metacarpophalangeal joints involves the movement at the base of each finger, where the palm's metacarpal bones meet the fingers' proximal phalanx bones. When discussing fingers 1 to 5, we refer to the thumb as finger 1 and the little finger as finger 5. The action of flexing these joints typically involves bending the fingers towards the palm, which is a crucial motion for tasks such as gripping. The metacarpophalangeal joints are biaxial joints that allow not only flexion and extension but also abduction, adduction, and circumduction movements. These joints are formed by the articulation between the distal end of the metacarpal bones of the hand and the proximal phalanx of each finger, including the thumb.
The muscles responsible for these movements are primarily located in the palm and the forearm. When these muscles contract, they cause the corresponding fingers to move. Furthermore, the first metacarpal bone has greater mobility compared to the other metacarpal bones, allowing for a wider range of motion at the thumb's metacarpophalangeal joint.